WO2005029017A1 - Photon detecting apparatus and photon detecting method - Google Patents

Photon detecting apparatus and photon detecting method Download PDF

Info

Publication number
WO2005029017A1
WO2005029017A1 PCT/JP2004/013063 JP2004013063W WO2005029017A1 WO 2005029017 A1 WO2005029017 A1 WO 2005029017A1 JP 2004013063 W JP2004013063 W JP 2004013063W WO 2005029017 A1 WO2005029017 A1 WO 2005029017A1
Authority
WO
WIPO (PCT)
Prior art keywords
voltage
pulse
photon
photon detection
avalanche
Prior art date
Application number
PCT/JP2004/013063
Other languages
French (fr)
Japanese (ja)
Inventor
Akio Yoshizawa
Original Assignee
National Institute Of Advanced Industrial Science And Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Institute Of Advanced Industrial Science And Technology filed Critical National Institute Of Advanced Industrial Science And Technology
Publication of WO2005029017A1 publication Critical patent/WO2005029017A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/44—Electric circuits
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/02016—Circuit arrangements of general character for the devices
    • H01L31/02019—Circuit arrangements of general character for the devices for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02027—Circuit arrangements of general character for the devices for devices characterised by at least one potential jump barrier or surface barrier for devices working in avalanche mode

Definitions

  • the present invention relates to a photon detection device required in the field of optical communication that requires photon detection (information processing field (quantum cryptography, etc.), the field of applied optical measurement such as laser lidar that requires detection of extremely weak light, etc. And a photon detection method including an after-pulse noise suppression method as a basic principle thereof.
  • Patent 1 and non-patent papers 1 and 2 which show conventional techniques, have almost the same principle of photon detection and are called an active-tain method.
  • a voltage exceeding the breakdown voltage is applied across the avalanche photodiode as the light-receiving element, and when avalanche amplification of electron holes due to photon detection occurs, resistor A causes avalanche amplification current. Is converted to a voltage, and the comparator compares the voltage observed at resistor B, which is unrelated to avalanche amplification, with the voltage across resistor A when avalanche occurs, detects avalanche amplification, and the comparator detects the voltage pulse.
  • the resistor B and the capacitor on the input side of the comparator are used to eliminate the charge pulse and the discharge pulse generated by the avalanche photodiode by the comparator. At the end of voltage pulse application, the voltage across the avalanche photodiode exceeds the breakdown voltage again.
  • the active pulse method suppresses after-pulse noise by adjusting the width of the voltage pulse that is fed back. Specifically, the generation of after-pulse noise can be suppressed by increasing the voltage pulse width generated by the comparator. However, the next photon detection cannot be started until the voltage pulse ends, so if the pulse width becomes longer, the photon detector stops. The time will be longer.
  • the DC voltage is set lower than the breakdown voltage of the avalanche photodiode, and the sum voltage is avalanche photodiode by superimposing a narrow voltage pulse that also generates a pulse generator power. It suppresses the generation of after-pulse noise by limiting the time during which the breakdown voltage of the diode is exceeded, and suppressing the avalanche amplification of electron holes by photon detection.
  • Non-Patent Documents 3 to 6 which show conventional techniques, have almost the same principle of photon detection and are called a gate operation method.
  • Figure 5 shows an example of a photon detection circuit.
  • the gate operation the DC voltage is set lower than the breakdown voltage of the avalanche photodiode, and the gate signal (voltage pulse) generated from the voltage pulse generator is biased. This limits the time for the sum voltage to exceed the breakdown voltage of the avalanche photodiode, converts the electron-hole avalanche amplification current generated by photon detection into a voltage with resistor A, Perform photon detection without.
  • the capacitor and resistor B are used for impedance matching.
  • FIG. 6 shows an example of photon detection.
  • the upper row shows the gate signal generated from the pulse generator
  • the middle row shows the measured value obtained by converting the avalanche amplification current generated by photon detection into a voltage
  • the lower row shows the measured value when no photon is detected.
  • the avalanche photodiode functions as a capacitor and charges the avalanche photodiode near the rising edge of the gate signal. The avalanche photodiode is discharged near the fall.
  • Non-Patent Document 3 the gate is set to 2 ns, in Non-Patent Document 4, the gate is set to 2.4 ns, and in Non-Patent Document 5, the power is set to 3.5 ns.As described later, in order to effectively suppress afternoise noise, Requires that the gate be below Ins to reduce the size of the avalanche amplification.
  • Non-Patent Documents 7 and 8 disclose that a charge pulse of an avalanche photodiode is removed. "In order to detect photons accurately, it is necessary to make the voltage change due to avalanche amplification sufficiently larger than the charge pulse. . "Has been removed. If the charging pulse is removed, the above restriction is eliminated, and the occurrence of after-pulse noise can be suppressed by reducing the scale of the avalanche amplification.
  • FIG. 7 shows a photon detection circuit of Non-Patent Document 7.
  • the DC voltage is set lower than the breakdown voltage of the avalanche photodiode by using a capacitor and a resistor, and the gate signal (voltage pulse) generated by the pulse generator is superimposed on the DC voltage via the capacitor.
  • the coaxial cable A having one open end is connected as a delay line to the cathode side of the avalanche photo diode via a capacitor, and the coaxial cable B having one end short-circuited is connected to the anode side as a delay line.
  • the charging pulse generated on the anode side at the time of rising of the gate signal is divided into two. One is output directly, and the other propagates through the coaxial cable B, but the charging pulse is negatively inverted and reflected to the anode side because one end is short-circuited.
  • the gate signal is also split into two parts on the cathode side, and a part of the gate signal propagates through the coaxial cable A. Since the coaxial cable A is open at one end, the gate signal is reflected without inversion.
  • Non-patent Document 7 since the after-pulse noise that sets the gate to Ins increases in proportion to the avalanche amplification scale, a relatively small avalanche amplification can be detected by removing the charging pulse. . For this reason, it can be said that this method is effective for after-pulse noise suppression. .
  • the lengths of the two coaxial cables must be exactly the same, and the propagation loss of the two must also be the same. This is a very difficult task.
  • the coaxial cable described in FIG. 5 does not have such a limitation. Further, as an electronic circuit, the configuration of FIG. 5 is simpler than that of FIG.
  • Figure 8 shows the photon detection circuit of Non-Patent Document 8.
  • the anode side of the two avalanche photodiodes is connected via resistors A and B, and the DC voltage is set lower than the breakdown voltage of both.
  • the gate signal voltage pulse
  • the time during which the sum voltage exceeds the breakdown voltage of the avalanche photodiode is limited.
  • the charge pulse generated on the anode side of the avalanche photodiode A and the charge pulse generated on the anode side of the avalanche photodiode B are input to the divider, thereby eliminating the charge pulse.
  • a pulse height discriminator A with a positive threshold value and a pulse height discriminator B with a negative threshold value are prepared for photon detection.
  • a voltage pulse is generated from the pulse height discriminator A, and in the case of the avalanche photodiode B, a voltage pulse is generated from the pulse height discriminator B.
  • Non-Patent Document 7 since the charged pulse is removed, relatively small avalanche amplification can be detected.
  • the gate signal width was set to 0.75 ns. Since afterpulse noise increases in proportion to the scale of avalanche amplification, using a gate signal with a short width to detect a photon while suppressing avalanche growth is effective in suppressing afterpulse noise.
  • Patent Document 1 US Patent No. 5532474
  • Non-Patent Document 1 Applied Optics Volume 35, Number 12, p. 1956 (Published in 1996)
  • Non-Patent Document 2 Applied Optics Volume 40, Number 33, p. 6012 (Issued 2001)
  • Non-Patent Document 3 Japanese Journal of Apllied Physics Part 1 Volume 40, Number 1, p. 200 (2000)
  • Non-Patent Document 4 Journal of Modern Optics Volume 48, Number 13, p. 1967 (Published year 2001)
  • Non-Patent Document 5 Journal of Modern Optics Volume 48, Number 13, p. 1983 (Published year 2001)
  • Non-Patent Document 6 Optics Letters Volume 27, Number 11, p. 954 (2002)
  • Non-Patent Document 7 IEEE Journal of Quantum Electronics Volume 36, Number 3, p. 340 (2000)
  • Non-Patent Document 8 Optics Letters Volume 27, Number 20, p. 1827 (Published year 2002)
  • Non-Patent Document 8 it is necessary to always prepare two avalanche photodiodes having the same characteristics. Furthermore, when avalanche amplification occurs due to photon detection simultaneously in two avalanche photodiodes, the two are canceled by the divider, and the output becomes zero.
  • the disadvantage of this method is that despite the use of two avalanche photodiodes, avalanche amplification by two photon detectors cannot be detected correctly even if avalanche amplification occurs simultaneously due to photon detection. On the point.
  • Non-Patent Documents 7 and 8 the charge pulse of the avalanche photodiode is removed, so that photon detection can be performed while suppressing the growth of avalanche amplification using a gate signal with a short width. Therefore, according to Non-Patent Document 7, it is necessary to match the lengths of the two coaxial cables and match the propagation loss between the two coaxial cables. In Non-Patent Document 8, it is necessary to always prepare two avalanche photodiodes having the same characteristics. Avalanche photodiodes have subtle characteristics between elements. Because they are different, it is difficult to always prepare one with the same characteristics. Also, it is complicated to make the lengths of the two coaxial cables equal and to make the propagation losses of the two coaxial cables equal.
  • An object of the present invention is to provide a photon detection device capable of simply and easily suppressing after-pulse noise of a photon detection device without removing charging pulses of an avalanche photodiode, in view of the above-described problems of the conventional example.
  • An apparatus and a photon detection method are provided.
  • the present invention employs the following solution in order to solve the above problems.
  • a photon detecting means using an avalanche photodiode as a light receiving element, a bias tee for applying a voltage to the avalanche photodiode, and a DC voltage generator for applying a DC voltage as a bias voltage to the biasy
  • a voltage pulse generator that applies a pulse voltage to the bias tee to operate the detection means only at a scheduled photon detection time, and a wave height discriminator that determines whether a photon is detected.
  • the DC voltage is set to be lower than the breakdown voltage of the avalanche photodiode by a device, and a narrow voltage pulse generated from the pulse generator is superimposed at a scheduled photon arrival time via a bias tee.
  • the sum voltage comprising the voltage pulse is applied to the avalanche photodiode. Characterized in that was.
  • the DC voltage is set lower than the breakdown voltage of the avalanche photodiode, and the voltage pulse generated by the voltage pulse generator is superposed.
  • the invention is characterized in that the time during which the sum voltage exceeds the breakdown voltage is limited, and the time and scale of the avalanche amplification of electron holes by photon detection are limited.
  • the peak of the pulse height discriminator the peak potential of the discharge pulse when there is no avalanche amplification and the discharge pulse when there is avalanche amplification.
  • a peak value is set to an arbitrary value between the potentials, and a discharge pulse generated by the avalanche photodiode at the falling position of the voltage pulse is input to the wave height discriminator. Only in this case, the pulse height discriminator force voltage pulse is output.
  • the pulse height discriminator force described in the above description is used to detect a non-photon in response to a discharge pulse generated when no photon is detected.
  • the feature is that a threshold value is set in advance so that a meaningful voltage pulse is generated.
  • the discharge pulse generated when a photon is detected is generated when the avalanche photodiode functions as a low resistor.
  • the output is smaller than the discharge pulse generated, and the output of the crest discriminator force described above is applied only to the small discharge pulse.
  • the value is set in advance so that there is no value.
  • the photon detection method includes a photon detection means using an avalanche photodiode as a light receiving element, a bias tee for applying a voltage to the avalanche photodiode, and a DC voltage generator for applying a DC voltage to the bias tee as a bias voltage.
  • a voltage pulse generator that applies a pulse voltage to the bias tee to operate the detection means only at the scheduled photon detection time, and a wave height discriminator that determines whether a photon has been detected.
  • the photon detection device of the present invention provides two coaxial cables or two avalanche photodiodes, which have been tried in the conventional example, as after-pulse noise suppression means of a photon detection device using an avalanche photodiode as a light receiving element. As a result, it is possible to easily and easily suppress the generation of after-pulse noise as compared with a method using the method.
  • the photon detection method of the present invention is based on the after-pulse noise suppression method, which is a basic principle, and detects photons while suppressing after-pulse noise accurately and continuously without requiring complicated adjustment work. It can be performed.
  • FIG. 1 is an explanatory diagram of a photon detection device and an after-pulse noise suppression method of the present invention.
  • FIG. 2 is an explanatory diagram of photon detection by the photon detection device of the present invention.
  • FIG. 3 is an explanatory diagram of an after-pulse noise occurrence probability by the photon detection device of the present invention.
  • ⁇ 4] is an explanatory view of a photon detection device for explaining Non-Patent Document 1.
  • FIG. 5 is an explanatory diagram of a photon detection device for explaining Non-Patent Document 3.
  • FIG. 6 is an explanatory diagram of photon detection for explaining Non-Patent Document 3.
  • FIG. 7 is an explanatory diagram of a photon detection device for explaining Non-Patent Document 7.
  • FIG. 8 is an explanatory diagram of a photon detection device for explaining Non-Patent Document 8.
  • the photon detection device of the present invention basically includes a photon detection means using an avalanche photodiode as a light receiving element, a DC voltage generator for applying a DC voltage lower than a breakdown voltage to the avalanche photodiode, and a gate signal ( A voltage pulse generator that causes the sum voltage to exceed the breakdown voltage only when a voltage pulse is output, a bias tee that creates the sum voltage, and a wave height discriminator that performs photon detection based on the presence or absence of a discharge pulse. Construct a photon detector.
  • the photon detection method of the present invention is a photon detection method device including an after-pulse noise suppression method as a basic principle, wherein the DC voltage is set to be lower than the breakdown voltage of the avalanche photodiode by the DC voltage generator.
  • the procedure consists of applying b.
  • avalanche photo diode avalanche amplification occurs inside the avalanche photodiode, and the avalanche photodiode functions as a low resistor. If no photon is detected, no avalanche amplification occurs and the avalanche photodiode functions as a capacitor.
  • whether the avalanche photodiode functions as a low resistor or as a capacitor is determined by the magnitude of the discharge pulse, and photon detection is performed. Specifically, we focused on the fact that the discharge pulse generated when a photon was not detected and the force applied was significantly smaller than the discharge pulse generated when a photon was detected.
  • a threshold is set in advance so that the output is nil.
  • FIG. 1 is a configuration diagram of a photon detection device provided with the photon detection means of the present invention.
  • the photon detector of FIG. 1 includes an avalanche photodiode 1 serving as a light receiving element, a DC voltage generator 2 for applying a DC voltage lower than a breakdown voltage to the avalanche photodiode, and a pulse for outputting a gate signal (voltage pulse).
  • Generator 3 bias tee for creating sum voltage 4
  • resistor 5 for converting charging current pulse to voltage change
  • wave height discriminator 6 for judging presence or absence of charging voltage pulse 6
  • resistor 7 necessary for impedance matching
  • capacitor Consists of eight of eight.
  • the photon detection means is a means for detecting a conduction state and a non-conduction state during avalanche amplification of an avalanche photodiode as a voltage change or a current change. And a series circuit of a resistor and a capacitor connected between the cathode of the avalanche photodiode and the ground terminal of the resistor.
  • a photon is incident on the avalanche photodiode 1 at a preset scheduled photon arrival time.
  • the gate signal generated from the voltage pulse generator 2 is applied to the avalanche photodiode 1 near the estimated photon arrival time, and the range in which the sum voltage exceeds the breakdown voltage of the avalanche photodiode 1 is limited to near the expected photon arrival time. You. In other words, the time during which the sum voltage exceeds the breakdown voltage is limited, and the time and scale of avalanche amplification of electron holes by photon detection are limited. Thereby, generation of an after pulse can be suppressed.
  • FIG. 1 The configuration of FIG. 1 is the same as that of FIG. 5 shown in the conventional example except for the wave height discriminator. However, in the present invention, the configuration of FIG. 1 is for detecting a discharge pulse of the avalanche photodiode 1. This configuration is adopted. Photon detection according to the present invention is completely different from the prior art in which avalanche amplification is detected to perform photon detection. Although two coaxial cables are shown in FIG. 1, unlike the non-patent document 7, it is not necessary to completely match the length and the loss.
  • the threshold of the wave height discriminator is set to an arbitrary value between the top potential of the discharge pulse when avalanche amplification is not performed and the apex potential of the discharge pulse when avalanche amplification is performed, and a voltage pulse is set.
  • the pulse generated by the avalanche photodiode at the falling edge of the pulse is input to the pulse height discriminator, and the voltage pulse is output from the pulse height discriminator only for the discharge pulse exceeding the threshold.
  • FIG. 2 shows an example of a voltage change observed at both ends of the resistor 5 when the photon detection device is operated.
  • This voltage is the input signal of the wave height discriminator 6.
  • the upper part of Fig. 2 shows the case where avalanche amplification occurred due to photon detection, and the lower part shows the case where no avalanche amplification occurred without photon detection.
  • a charge pulse with a positive sign (pulse C) and a discharge pulse with a negative sign (pulse D) are observed because the avalanche photodiode 1 functions as a capacitor.
  • the other vibration components are noise due to impedance mismatch and have nothing to do with photon detection.
  • the threshold value of the wave height discriminator 6 is set to a position as shown in FIG.
  • a voltage norm is generated from the wave height discriminator 6, and when a photon is detected, the output from the wave height discriminator 6 is nil. It can be determined.
  • avalanche occurs due to photon detection, but the size of the avalanche is very small compared to the magnitude of the charging pulse (pulse C), and it cannot be confirmed in the figure. Since afterpulse noise increases in proportion to the avalanche amplification scale, photons can be detected with a very small avalanche scale compared to the charge pulse (pulse C). This method is extremely effective in suppressing afterpulse noise.
  • FIG. 3 shows the probability of occurrence of after-pulse noise.
  • the vertical axis is shown in percentage (%), and the horizontal axis is Indicates elapsed time s). In general, the occurrence of afterpulses decreases with time.
  • the black circles in the figure indicate the experimental results according to the present invention, and the black circles indicate the after-pulse generation probability when the photoinduced avalanche amplification current shown in FIG. 6 is detected as a voltage change.
  • the gate is set to Ins.
  • a long (2 ns) gate was used to grow the avalanche amplification beyond the charge pulse, as shown in Figure 6. Incidentally, both the measurement of FIG.
  • the repetition frequency is 5 MHz
  • quantum efficiency Ri near near 15%
  • the dark count rate is about 5 X 10- 5.
  • this method can detect photons with an avalanche size that is very small compared to the charging pulse.
  • the avalanche amplification is larger than the charging pulse. Since afterpulse noise increases in proportion to the size of the avalanche amplification, the effectiveness of this method, which can detect photons in a state where the avalanche amplification is very small compared to the charging pulse (pulse A in Fig. 2), is demonstrated. It was confirmed from the measurement comparison results of 3.
  • the photon detection operation can be performed at high speed in principle. Therefore, the key generation rate can be improved in the field of cryptographic communication using quantum cryptography.
  • a key generation rate of 45 kbitZ seconds has been achieved with an optical fiber length of 10.5 km using a key distribution protocol B92 for a repetition frequency of 10 MHz.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Light Receiving Elements (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Abstract

Photon detecting apparatus and method capable of simply and easily suppressing afterpulse noise of the photon detecting apparatus without performing a charge pulse elimination of an avalanche photodiode. The photo detecting apparatus comprises photon detecting means using an avalanche photodiode as a light receiving element; a bias tee for applying a voltage to the avalanche photodiode; a DC voltage generator for applying a DC voltage, as a bias voltage, to the bias tee; a voltage pulse generator for applying a pulse voltage to the bias tee to cause the detecting means to operate only at a scheduled photon detection time; and a pulse-amplitude discriminator for determining whether any photon has been detected. The DC voltage generator is adapted to generate the DC voltage that is lower than the breakdown voltage of the avalanche photodiode. A narrow-width voltage pulse generated by the pulse generator at a scheduled photon arrival time is superimposed on the DC voltage via the bias tee, thereby applying the summed voltage, which comprises the DC voltage and the voltage pulse, to the avalanche photodiode.

Description

明 細 書  Specification
光子検出装置および光子検出方法  Photon detection device and photon detection method
技術分野  Technical field
[0001] 本発明は、光子検出を必要とする光通信'情報処理分野 (量子暗号等）、レーザー ライダー等の極微弱光検出を必要とする光応用計測分野、等で必要となる光子検出 装置及びその基本原理となるアフターパルス雑音抑圧法を含む光子検出方法に関 する。  [0001] The present invention relates to a photon detection device required in the field of optical communication that requires photon detection (information processing field (quantum cryptography, etc.), the field of applied optical measurement such as laser lidar that requires detection of extremely weak light, etc. And a photon detection method including an after-pulse noise suppression method as a basic principle thereof.
背景技術  Background art
[0002] 従来の技術を示す特許 1と非特許論文 1と 2は光子検出の原理がほぼ同一でありァ クティブタエンチ方式と呼ばれて 、る。図 4に示すようにアクティブタエンチ方式では 受光素子であるアバランシェフオトダイオードの両端に降伏電圧を超える電圧が印加 され、光子検出による電子正孔のなだれ増幅が発生すると、抵抗器 Aがなだれ増幅 電流を電圧に変換し、なだれ増幅と無関係な抵抗器 Bで観測される電圧となだれ発 生時の抵抗器 Aの両端電圧を比較器が比較し、なだれ増幅を検知し、比較器が電 圧パルスを発生し、その一部を差動増幅器経由でアバランシェフオトダイオードに帰 還することで、アバランシェフオトダイオードの両端電圧が降伏電圧以下となり、なだ れが終息する。比較器の入力側にある抵抗器 Bとコンデンサ一は、アバランシェフオト ダイオードが発生する充電パルスと放電パルスを比較器で除去するために使用する 。電圧ノ ルス印加が終了した時点で、アバランシェフオトダイオードの両端電圧が再 度降伏電圧を超える。  [0002] Patent 1 and non-patent papers 1 and 2, which show conventional techniques, have almost the same principle of photon detection and are called an active-tain method. As shown in Fig. 4, in the active-taench method, a voltage exceeding the breakdown voltage is applied across the avalanche photodiode as the light-receiving element, and when avalanche amplification of electron holes due to photon detection occurs, resistor A causes avalanche amplification current. Is converted to a voltage, and the comparator compares the voltage observed at resistor B, which is unrelated to avalanche amplification, with the voltage across resistor A when avalanche occurs, detects avalanche amplification, and the comparator detects the voltage pulse. Is generated, and a part of the voltage is returned to the avalanche photodiode via the differential amplifier, so that the voltage across the avalanche photodiode becomes less than the breakdown voltage, and the avalanche ends. The resistor B and the capacitor on the input side of the comparator are used to eliminate the charge pulse and the discharge pulse generated by the avalanche photodiode by the comparator. At the end of voltage pulse application, the voltage across the avalanche photodiode exceeds the breakdown voltage again.
[0003] そこで、同様の動作を繰り返しながら光子検出を連続的に行う。アフターパルス雑 音はなだれ増幅の規模に比例して増大する傾向にあるが、なだれ増幅の終息後、時 間の経過とともにその発生確率は低下する。  [0003] Therefore, photon detection is continuously performed while repeating the same operation. After-pulse noise tends to increase in proportion to the size of avalanche amplification, but its probability decreases with time after the avalanche amplification ends.
アクティブタエンチ方式では帰還する電圧パルスの幅を調整することでアフターパ ルス雑音を抑圧する。具体的には、アフターパルス雑音の発生は比較器が発生する 電圧パルス幅を長くすることで抑えることができる。但し、電圧パルスが終了しないと 次の光子検出を開始できないため、パルス幅が長くなると光子検出装置が休止する 時間も長くなる。本発明で提案するアフターパルス雑音抑圧法では直流電圧をアバ ランシェフオトダイオードの降伏電圧よりも低めに設定し、パルス発生器力も発生する 狭幅の電圧パルスを重畳することで、和電圧がアバランシェフオトダイオードの降伏 電圧を超過する時間を制限し、光子検出による電子正孔のなだれ増幅の規模を抑え ることでアフターパルス雑音の発生を抑圧する。 The active pulse method suppresses after-pulse noise by adjusting the width of the voltage pulse that is fed back. Specifically, the generation of after-pulse noise can be suppressed by increasing the voltage pulse width generated by the comparator. However, the next photon detection cannot be started until the voltage pulse ends, so if the pulse width becomes longer, the photon detector stops. The time will be longer. In the after-pulse noise suppression method proposed in the present invention, the DC voltage is set lower than the breakdown voltage of the avalanche photodiode, and the sum voltage is avalanche photodiode by superimposing a narrow voltage pulse that also generates a pulse generator power. It suppresses the generation of after-pulse noise by limiting the time during which the breakdown voltage of the diode is exceeded, and suppressing the avalanche amplification of electron holes by photon detection.
[0004] 従来の技術を示す非特許文献 3から 6までは光子検出の原理がほぼ同一でありゲ ート動作方式と呼ばれている。図 5に光子検出回路の一例を示すが、ゲート動作で は直流電圧をアバランシェフオトダイオードの降伏電圧よりも低めに設定し、電圧パ ルス発生器カゝら発生するゲート信号 (電圧パルス）をバイアスティで重畳することで、 和電圧がアバランシェフオトダイオードの降伏電圧を超過する時間を制限し、光子検 出により発生する電子正孔のなだれ増幅電流を抵抗器 Aで電圧に変換し、電圧の有 無で光子検出を行う。コンデンサーと抵抗器 Bはインピーダンス整合に用いる。  [0004] Non-Patent Documents 3 to 6, which show conventional techniques, have almost the same principle of photon detection and are called a gate operation method. Figure 5 shows an example of a photon detection circuit. In the gate operation, the DC voltage is set lower than the breakdown voltage of the avalanche photodiode, and the gate signal (voltage pulse) generated from the voltage pulse generator is biased. This limits the time for the sum voltage to exceed the breakdown voltage of the avalanche photodiode, converts the electron-hole avalanche amplification current generated by photon detection into a voltage with resistor A, Perform photon detection without. The capacitor and resistor B are used for impedance matching.
[0005] 図 6に光子検出の一例を示す。上段が、パルス発生器から発生するゲート信号、中 段は、光子検出により発生したなだれ増幅電流を電圧変換した測定値、下段は、光 子が検出されな力つた場合の測定値である。下段に示すように、光子が検出されず、 なだれ増幅が発生しない場合には、アバランシェフオトダイオードがコンデンサ一とし て機能するため、ゲート信号の立ち上がり付近でアバランシェフオトダイオードが充電 され、ゲート信号の立ち下がり付近でアバランシェフオトダイオードが放電される。  FIG. 6 shows an example of photon detection. The upper row shows the gate signal generated from the pulse generator, the middle row shows the measured value obtained by converting the avalanche amplification current generated by photon detection into a voltage, and the lower row shows the measured value when no photon is detected. As shown in the lower part, when no photons are detected and no avalanche amplification occurs, the avalanche photodiode functions as a capacitor and charges the avalanche photodiode near the rising edge of the gate signal. The avalanche photodiode is discharged near the fall.
[0006] この結果、小さな正電圧パルス（充電パルス、図中、パルス A)と負電圧パルス（放 電パルス、図中、パルス B)が観測される。他の振動成分はインピーダンス不整合に よる雑音であり、光子検出とは無関係である。中段では、なだれ増幅による電圧変化 (図中、ノ ルス C)が観測される。前述の通り、アフターパルス雑音はなだれ増幅の規 模に比例して増大するため、ゲート幅を短くしてなだれの成長を抑える必要がある。 但し、充電パルスは常に存在するため、なだれ増幅による電圧変化が充電パルスに 比べて十分大きい方が光子検出を精度良く行うために望ましい。仮に、なだれ増幅 による電圧変化（図中、パルス C)が充電パルス（図中、パルス A)に比べて同等、或 いは、小さい場合、両者を区別することが困難になる。  [0006] As a result, a small positive voltage pulse (charging pulse, pulse A in the figure) and a negative voltage pulse (discharge pulse, pulse B in the figure) are observed. The other vibration components are noise due to impedance mismatch and have nothing to do with photon detection. In the middle stage, a voltage change (north C in the figure) due to avalanche amplification is observed. As mentioned above, since after-pulse noise increases in proportion to the scale of avalanche amplification, it is necessary to reduce the gate width to suppress avalanche growth. However, since the charging pulse always exists, it is desirable that the voltage change due to the avalanche amplification is sufficiently large as compared with the charging pulse in order to perform photon detection with high accuracy. If the voltage change (pulse C in the figure) due to avalanche amplification is equal to or smaller than the charging pulse (pulse A in the figure), it will be difficult to distinguish between the two.
[0007] 一般に、なだれが成長して大きな電圧パルスとして観測されるためには、ゲート幅を 長めに設定して、ある程度の時間、なだれの成長を維持する必要があり、本検出方 式ではアフターパルス雑音の発生を抑制することが難 、。非特許文献 3ではゲート を 2ns、非特許文献 4ではゲートを 2. 4ns、非特許論文 5では 3. 5nsに設定している 力 後述するように、アフターノ ルス雑音を効果的に抑圧するためにはゲートを Ins 以下にして、なだれ増幅の規模を縮小する必要がある。 [0007] Generally, in order for an avalanche to grow and be observed as a large voltage pulse, the gate width must be reduced. It is necessary to keep the avalanche growth for a certain period of time by setting it to a longer length, and it is difficult to suppress the generation of after-pulse noise with this detection method. In Non-Patent Document 3, the gate is set to 2 ns, in Non-Patent Document 4, the gate is set to 2.4 ns, and in Non-Patent Document 5, the power is set to 3.5 ns.As described later, in order to effectively suppress afternoise noise, Requires that the gate be below Ins to reduce the size of the avalanche amplification.
[0008] 非特許文献 7と 8はアバランシェフオトダイオードの充電パルスを除去することで、「 精度良く光子検出を行うためには、なだれ増幅による電圧変化を充電パルスに比べ て十分大きくする必要がある。」という制約を取り除いている。充電パルスが除去され れば、上記の制約がなくなり、なだれ増幅の規模を縮小することでアフターパルス雑 音の発生を抑圧することができる。  [0008] Non-Patent Documents 7 and 8 disclose that a charge pulse of an avalanche photodiode is removed. "In order to detect photons accurately, it is necessary to make the voltage change due to avalanche amplification sufficiently larger than the charge pulse. . "Has been removed. If the charging pulse is removed, the above restriction is eliminated, and the occurrence of after-pulse noise can be suppressed by reducing the scale of the avalanche amplification.
[0009] 図 7に非特許文献 7の光子検出回路を示す。コンデンサーと抵抗器を利用して直 流電圧をアバランシェフオトダイオードの降伏電圧よりも低めに設定し、パルス発生器 力 発生するゲート信号 (電圧パルス）をコンデンサー経由で直流電圧に重畳するこ とで、和電圧がアバランシェフオトダイオードの降伏電圧を超過する時間を制限する。 このとき、片端を開放した同軸ケーブル Aを遅延線としてアバランシェフオトダイォー ドの陰極側にコンデンサーを介して接続し、更に、片端を短絡した同軸ケーブル Bを 遅延線として陽極側に接続する。  FIG. 7 shows a photon detection circuit of Non-Patent Document 7. The DC voltage is set lower than the breakdown voltage of the avalanche photodiode by using a capacitor and a resistor, and the gate signal (voltage pulse) generated by the pulse generator is superimposed on the DC voltage via the capacitor. Limits the time during which the sum voltage exceeds the breakdown voltage of the avalanche photodiode. At this time, the coaxial cable A having one open end is connected as a delay line to the cathode side of the avalanche photo diode via a capacitor, and the coaxial cable B having one end short-circuited is connected to the anode side as a delay line.
[0010] この構成により、ゲート信号の立ち上がり時に陽極側で発生する充電パルスが二分 される。一つは直接出力され、もう一つは、同軸ケーブル Bを伝搬するが、片端が短 絡されているため充電パルスは負反転されて陽極側に反射してくる。また、陰極側で もゲート信号が二分され、一部が同軸ケーブル Aを伝搬する。同軸ケーブル Aでは、 片端が開放されているため、無反転でゲート信号が反射する。負符号を持つ充電パ ルスと同軸ケーブル Aから陰極側に反射してくる無反転のゲート信号の立ち上がり時 に陽極側で発生する充電パルスとが時間的に重なり、符号が正負異なるため両者が 相殺され、充電パルスが除去される仕組みになっている。  [0010] With this configuration, the charging pulse generated on the anode side at the time of rising of the gate signal is divided into two. One is output directly, and the other propagates through the coaxial cable B, but the charging pulse is negatively inverted and reflected to the anode side because one end is short-circuited. The gate signal is also split into two parts on the cathode side, and a part of the gate signal propagates through the coaxial cable A. Since the coaxial cable A is open at one end, the gate signal is reflected without inversion. The charge pulse with a negative sign and the charge pulse generated on the anode side when the non-inverted gate signal reflected from the coaxial cable A to the cathode rises at the rising edge overlap in time, and the signs are different, so the two cancel each other out. Then, the charging pulse is removed.
[0011] 非特許文献 7では、ゲートを Insに設定している力 アフターパルス雑音はなだれ 増幅の規模に比例して増大するため、充電パルスを除去することで比較的小さなな だれ増幅を検知できる。このため、本方式はアフターパルス雑音抑圧に有効と言える 。但し、充電パルスを確実に除去するためには、二本の同軸ケーブルの長さを完全 に一致させ、両者の伝搬損失も一致させなければならない。これは大変困難な作業 である。 [0011] In Non-patent Document 7, since the after-pulse noise that sets the gate to Ins increases in proportion to the avalanche amplification scale, a relatively small avalanche amplification can be detected by removing the charging pulse. . For this reason, it can be said that this method is effective for after-pulse noise suppression. . However, in order to reliably eliminate the charging pulse, the lengths of the two coaxial cables must be exactly the same, and the propagation loss of the two must also be the same. This is a very difficult task.
[0012] これに対して図 5に記載されている同軸ケーブルにはこのような制限はない。更に、 電子回路としては図 5は図 7と比較して構成が簡単である。  [0012] On the other hand, the coaxial cable described in FIG. 5 does not have such a limitation. Further, as an electronic circuit, the configuration of FIG. 5 is simpler than that of FIG.
図 8に非特許文献 8の光子検出回路を示す。二個のアバランシェフオトダイオード の陽極側を抵抗器 A, B経由で接続し、直流電圧を両者の降伏電圧よりも低めに設 定している。電圧パルス発生器力も発生するゲート信号 (電圧パルス)を二分し、各ァ バランシェフオトダイオードの陰極側に印可することで、和電圧がアバランシェフオトダ ィオードの降伏電圧を超過する時間を制限する。ゲート信号の立ち上がり時に、アバ ランシェフオトダイオード Aの陽極側で発生する充電パルスとアバランシェフオトダイォ ード Bの陽極側で発生する充電パルスを除算器に入力することで充電パルスが除去 される。  Figure 8 shows the photon detection circuit of Non-Patent Document 8. The anode side of the two avalanche photodiodes is connected via resistors A and B, and the DC voltage is set lower than the breakdown voltage of both. By dividing the gate signal (voltage pulse) that also generates the voltage pulse generator into two and applying it to the cathode side of each avalanche photodiode, the time during which the sum voltage exceeds the breakdown voltage of the avalanche photodiode is limited. At the rising edge of the gate signal, the charge pulse generated on the anode side of the avalanche photodiode A and the charge pulse generated on the anode side of the avalanche photodiode B are input to the divider, thereby eliminating the charge pulse.
[0013] このとき、アバランシェフオトダイオード Aでなだれが発生すると、正電圧パルスが発 生し、 Bでなだれが発生すると、負電圧パルスが発生する。そこで、除算器の出力を 増幅器で増幅後、二分し、しきい値を正値に設定した波高弁別器 Aとしきい値を負値 に設定した波高弁別器 Bを用意して光子検出を行う。具体的には、アバランシェフォ トダイオード Aで発生したなだれが検知されると波高弁別器 Aから電圧パルスが発生 し、アバランシェフオトダイオード Bの場合、波高弁別器 Bから電圧パルスが発生する ので、両者を計数器 A, Bで別々に計数している。非特許論文 7と同様に、充電パル スが除去されているので、比較的小さななだれ増幅を検知することができる。実験で は、ゲート信号幅を 0. 75nsに設定している。アフターパルス雑音はなだれ増幅の規 模に比例して増大するため、幅の短いゲート信号を使用することでなだれの成長を 抑えながら光子検出を行う手法はアフターパルス雑音抑圧に有効である。  At this time, when avalanche occurs in the avalanche photodiode A, a positive voltage pulse is generated, and when avalanche occurs in B, a negative voltage pulse is generated. Therefore, the output of the divider is amplified by an amplifier, then divided into two, and a pulse height discriminator A with a positive threshold value and a pulse height discriminator B with a negative threshold value are prepared for photon detection. Specifically, when an avalanche generated by the avalanche photodiode A is detected, a voltage pulse is generated from the pulse height discriminator A, and in the case of the avalanche photodiode B, a voltage pulse is generated from the pulse height discriminator B. Are separately counted by the counters A and B. As in Non-Patent Document 7, since the charged pulse is removed, relatively small avalanche amplification can be detected. In the experiment, the gate signal width was set to 0.75 ns. Since afterpulse noise increases in proportion to the scale of avalanche amplification, using a gate signal with a short width to detect a photon while suppressing avalanche growth is effective in suppressing afterpulse noise.
[0014] 従来技術に関する特許文献 1件，非特許文献を 8件挙げる。  [0014] One patent document and eight non-patent documents relating to the prior art are listed.
特許文献 1：米国特許番号 5532474  Patent Document 1: US Patent No. 5532474
非特許文献 1 : Applied Optics Volume 35, Number 12, p. 1956 (発 行年 1996) 非特許文献 2 : Applied Optics Volume 40, Number 33, p. 6012 (発 行年 2001) Non-Patent Document 1: Applied Optics Volume 35, Number 12, p. 1956 (Published in 1996) Non-Patent Document 2: Applied Optics Volume 40, Number 33, p. 6012 (Issued 2001)
非特許文献 3 Japanese Journal of Apllied Physics Part 1 Volume 40 , Number 1, p. 200 (発行年 2000)  Non-Patent Document 3 Japanese Journal of Apllied Physics Part 1 Volume 40, Number 1, p. 200 (2000)
非特許文献 4 Journal of Modern Optics Volume 48, Number 13, p . 1967 (発行年 2001)  Non-Patent Document 4 Journal of Modern Optics Volume 48, Number 13, p. 1967 (Published year 2001)
非特許文献 5 Journal of Modern Optics Volume 48, Number 13, p . 1983 (発行年 2001)  Non-Patent Document 5 Journal of Modern Optics Volume 48, Number 13, p. 1983 (Published year 2001)
非特許文献 6 : Optics Letters Volume 27, Number 11, p. 954 (発行 年 2002)  Non-Patent Document 6: Optics Letters Volume 27, Number 11, p. 954 (2002)
非特許文献 7 : IEEE Journal of Quantum Electronics Volume 36, Nu mber 3, p. 340 (発行年 2000)  Non-Patent Document 7: IEEE Journal of Quantum Electronics Volume 36, Number 3, p. 340 (2000)
非特許文献 8 : Optics Letters Volume 27, Number 20, p. 1827 (発行 年 2002)  Non-Patent Document 8: Optics Letters Volume 27, Number 20, p. 1827 (Published year 2002)
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0015] し力しながら、非特許文献 8記載のものは、特性の一致したアバランシェフオトダイ オードを常に二個用意する必要がある。更に、二個のアバランシェフオトダイオードで 同時に光子検出によるなだれ増幅が発生した場合、除算器により両者は相殺され、 出力が零となる。この方式の欠点は、二個のアバランシェフオトダイオードを使用して いるにもかかわらず、二個のアバランシェフオトダイオードで同時に光子検出によるな だれ増幅が発生しても、それを正しく検知することができない点にある。  However, in the case of Non-Patent Document 8, it is necessary to always prepare two avalanche photodiodes having the same characteristics. Furthermore, when avalanche amplification occurs due to photon detection simultaneously in two avalanche photodiodes, the two are canceled by the divider, and the output becomes zero. The disadvantage of this method is that despite the use of two avalanche photodiodes, avalanche amplification by two photon detectors cannot be detected correctly even if avalanche amplification occurs simultaneously due to photon detection. On the point.
[0016] 非特許文献 7と 8では、アバランシェフオトダイオードの充電パルスが除去されるた め、幅の短いゲート信号を使用してなだれ増幅の成長を抑えながら光子検出を行うこ とができる。このため、アフターパルス雑音抑圧に有効と考えられる力 非特許文献 7 では、二本の同軸ケーブルの長さを一致させ、両者の伝搬損失も一致させる必要が ある。また、非特許文献 8では、常に、特性の一致したアバランシェフオトダイオードを 二個用意する必要がある。アバランシェフオトダイオードは素子間でも微妙に特性が 異なるため、特性の一致したものを常に用意することは困難である。また、二本の同 軸ケーブルの長さを一致させ、両者の伝搬損失も一致させる作業も煩雑である。 In Non-Patent Documents 7 and 8, the charge pulse of the avalanche photodiode is removed, so that photon detection can be performed while suppressing the growth of avalanche amplification using a gate signal with a short width. Therefore, according to Non-Patent Document 7, it is necessary to match the lengths of the two coaxial cables and match the propagation loss between the two coaxial cables. In Non-Patent Document 8, it is necessary to always prepare two avalanche photodiodes having the same characteristics. Avalanche photodiodes have subtle characteristics between elements. Because they are different, it is difficult to always prepare one with the same characteristics. Also, it is complicated to make the lengths of the two coaxial cables equal and to make the propagation losses of the two coaxial cables equal.
[0017] 本発明の目的は、上記従来例の問題点に鑑み、アバランシェフオトダイオードの充 電パルス除去を行わないで、光子検出装置のアフターパルス雑音を簡単、容易に抑 圧することができる光子検出装置および光子検出方法を提供するものである。  An object of the present invention is to provide a photon detection device capable of simply and easily suppressing after-pulse noise of a photon detection device without removing charging pulses of an avalanche photodiode, in view of the above-described problems of the conventional example. An apparatus and a photon detection method are provided.
課題を解決するための手段  Means for solving the problem
[0018] 本発明は、上記課題を解決するために、以下の解決手段を採用する。 The present invention employs the following solution in order to solve the above problems.
(1)光子検出装置において、アバランシェフオトダイオードを受光素子とする光子検 出手段と、アバランシェフオトダイオードに電圧を印加するバイアスティと、前記バイァ スティに直流電圧をバイアス電圧として印加する直流電圧発生器と、前記バイアステ ィにパルス電圧を印加し光子検出予定時刻でのみ前記検出手段を動作させる電圧 パルス発生器と、光子が検出されたか否かを判定する波高弁別器で構成され、前記 直流電圧発生器により前記直流電圧を前記アバランシェフオトダイオードの降伏電圧 よりも低めに設定し、光子到着予定時刻に前記パルス発生器から発生する狭幅の電 圧パルスをバイアスティ経由で重畳し、前記直流電圧と前記電圧パルスカゝらなる和電 圧を前記アバランシェフオトダイオードに印加するように構成したことを特徴とする。 (1) In a photon detecting device, a photon detecting means using an avalanche photodiode as a light receiving element, a bias tee for applying a voltage to the avalanche photodiode, and a DC voltage generator for applying a DC voltage as a bias voltage to the biasy A voltage pulse generator that applies a pulse voltage to the bias tee to operate the detection means only at a scheduled photon detection time, and a wave height discriminator that determines whether a photon is detected. The DC voltage is set to be lower than the breakdown voltage of the avalanche photodiode by a device, and a narrow voltage pulse generated from the pulse generator is superimposed at a scheduled photon arrival time via a bias tee. The sum voltage comprising the voltage pulse is applied to the avalanche photodiode. Characterized in that was.
(2)上記（1)記載の光子検出装置において、前記直流電圧を前記のアバランシェフ オトダイオードの降伏電圧よりも低めに設定し、前記電圧パルス発生器力 出力され る電圧パルスを重畳により、前記和電圧が前記降伏電圧を超過する時間を限定し、 光子検出による電子正孔のなだれ増幅の発生時間と規模を制限することを特徴とす る。 (2) In the photon detection device according to (1), the DC voltage is set lower than the breakdown voltage of the avalanche photodiode, and the voltage pulse generated by the voltage pulse generator is superposed. The invention is characterized in that the time during which the sum voltage exceeds the breakdown voltage is limited, and the time and scale of the avalanche amplification of electron holes by photon detection are limited.
(3)上記（2)記載の光子検出装置にお!、て、前記波高弁別器のしき!、値をなだれ増 幅が無いときの放電パルスの頂点電位となだれ増幅が有るときの放電パルスの頂点 電位の間の任意の値に設定し、前記電圧パルスの立ち下がり位置で前記アバランシ エフオトダイオードが発生する放電パルスを前記波高弁別器に入力し、前記しき 、値 を超える前記放電パルスに対してのみ、前記波高弁別器力 電圧パルスが出力され るように構成したことを特徴とする。  (3) In the photon detection device according to (2), the peak of the pulse height discriminator, the peak potential of the discharge pulse when there is no avalanche amplification and the discharge pulse when there is avalanche amplification. A peak value is set to an arbitrary value between the potentials, and a discharge pulse generated by the avalanche photodiode at the falling position of the voltage pulse is input to the wave height discriminator. Only in this case, the pulse height discriminator force voltage pulse is output.
(4)上記（1)な 、し (3)の 、ずれか 1項記載の光子検出装置にお!、て、光子が検出 される場合に、同記載のアバランシェフオトダイオード内部で電子正孔のなだれ増幅 が発生し、アバランシェフオトダイオードが低抵抗器として機能するように構成したこと を特徴とする。 (4) In the photon detector described in (1) above, (1), (2) or (3), photons are detected. In such a case, avalanche photo diode avalanche amplification occurs inside the avalanche photodiode described above, and the avalanche photodiode functions as a low resistor.
(5)上記（1)ないし（3)のいずれ力 1項記載の光子検出装置において、光子が検出 されなかった場合に、なだれ増幅が発生せず、前記アバランシェフオトダイオードがコ ンデンサ一として機能するように構成したことを特徴とする。  (5) In the photon detection device according to any one of (1) to (3), when no photon is detected, no avalanche amplification occurs and the avalanche photodiode functions as a capacitor. It is characterized by having such a configuration.
(6)上記（1)ないし（5)のいずれか 1項記載の光子検出装置において、光子が検出 されなかった場合に発生する放電パルスに対して、同記載の波高弁別器力 光子非 検出を意味する電圧パルスが発生するように予めしき ヽ値が設定されて ヽることを特 徴とする。 (6) In the photon detector according to any one of the above (1) to (5), the pulse height discriminator force described in the above description is used to detect a non-photon in response to a discharge pulse generated when no photon is detected. The feature is that a threshold value is set in advance so that a meaningful voltage pulse is generated.
(7)上記（1)ないし（5)のいずれ力 1項記載の光子検出装置において、光子が検出 された場合に発生する放電パルスはアバランシェフオトダイオードが低抵抗器として 機能するために、光子が検出されな力つた場合 (アバランシェフオトダイオードがコン デンサ一として機能する。）に発生する放電パルスと比較して小さくなり、前記の小さ な放電パルスに対してのみ同記載の波高弁別器力 の出力が無となるように予めし き 、値が設定されて 、ることを特徴とする。  (7) In the photon detection device according to (1), the discharge pulse generated when a photon is detected is generated when the avalanche photodiode functions as a low resistor. When the detected power is not applied (the avalanche photodiode functions as a capacitor), the output is smaller than the discharge pulse generated, and the output of the crest discriminator force described above is applied only to the small discharge pulse. The value is set in advance so that there is no value.
(8)上記（1)ないし（5)のいずれか 1項記載の光子検出装置において、光子が検出 されなかった場合に同記載の波高弁別器力 電圧パルスが発生し、光子が検出され た場合に前記波高弁別器力 の出力が無となることで、光子検出の有無を判断する ことを特徴とする。  (8) In the photon detector according to any one of the above (1) to (5), when a photon is not detected, a pulse height discriminator force voltage pulse described in the description is generated, and a photon is detected. In addition, the presence or absence of photon detection is determined by the absence of the output of the wave height discriminator force.
(9)光子検出方法は、アバランシェフオトダイオードを受光素子とする光子検出手段 と、アバランシェフオトダイオードに電圧を印加するバイアスティと、前記バイアスティ に直流電圧をバイアス電圧として印加する直流電圧発生器と、前記バイアスティにパ ルス電圧を印加し光子検出予定時刻でのみ前記検出手段を動作させる電圧パルス 発生器と、光子が検出されたか否かを判定する波高弁別器力 なる装置において、 前記直流電圧発生器により前記直流電圧を前記アバランシェフオトダイオードの降 伏電圧よりも低めに設定する手順 a、  (9) The photon detection method includes a photon detection means using an avalanche photodiode as a light receiving element, a bias tee for applying a voltage to the avalanche photodiode, and a DC voltage generator for applying a DC voltage to the bias tee as a bias voltage. A voltage pulse generator that applies a pulse voltage to the bias tee to operate the detection means only at the scheduled photon detection time, and a wave height discriminator that determines whether a photon has been detected. A) setting the DC voltage by a generator to be lower than the breakdown voltage of the avalanche photodiode;
光子到着予定時刻に前記パルス発生器カゝら発生する狭幅の電圧パルスをバイアス ティ経由で重畳し、前記直流電圧と前記電圧パルスからなる和電圧を前記アバラン シェフオトダイオードに印加する手順 b、 Bias the narrow voltage pulse generated by the pulse generator at the expected time of arrival of photons Superimposing via a tee, applying a sum voltage comprising the DC voltage and the voltage pulse to the avalanche chef photodiode, b.
力 なることを特徴とする。  It is characterized by power.
(10)上記（9)記載の光子検出方法は、前記手順 aの前に、前記波高弁別器のしき V、値をなだれ増幅が無 、ときの放電パルスの頂点電位となだれ増幅が有るときの放 電パルスの頂点電位の間の任意の値に設定し、前記電圧パルスの立ち下がり位置 で前記アバランシェフオトダイオードが発生する放電パルスを前記波高弁別器に入 力し、前記しきい値を超える前記放電パルスに対してのみ、前記波高弁別器から電 圧パルスが出力されるように設定する手順を設けたことを特徴とする。  (10) The photon detection method according to (9) above, wherein before the step a, the threshold V of the wave height discriminator, the avalanche amplification value is absent, and the apex potential of the discharge pulse when avalanche amplification is present. A discharge pulse generated by the avalanche photodiode at the falling position of the voltage pulse is input to the pulse height discriminator at an arbitrary value between the peak potentials of the discharge pulse, and the value exceeds the threshold. It is characterized in that a procedure is provided for setting such that a voltage pulse is output from the pulse height discriminator only for a discharge pulse.
発明の効果  The invention's effect
[0019] 本発明の光子検出装置は、アバランシェフオトダイオードを受光素子とする光子検 出装置のアフターパルス雑音抑圧手段として、従来例で試みられた二本の同軸ケー ブルや二個のアバランシェフオトダイオードを用いる手段等と比較して、アフターパル ス雑音の発生を簡単、容易に抑えることができる。  The photon detection device of the present invention provides two coaxial cables or two avalanche photodiodes, which have been tried in the conventional example, as after-pulse noise suppression means of a photon detection device using an avalanche photodiode as a light receiving element. As a result, it is possible to easily and easily suppress the generation of after-pulse noise as compared with a method using the method.
また、本発明の光子検出方法は、基本原理となるアフターパルス雑音抑圧法に基 づいて、複雑な調整作業等を要せずに、正確且つより連続的にアフターパルス雑音 を抑圧しながら光子検出を行うことができる。  Further, the photon detection method of the present invention is based on the after-pulse noise suppression method, which is a basic principle, and detects photons while suppressing after-pulse noise accurately and continuously without requiring complicated adjustment work. It can be performed.
図面の簡単な説明  Brief Description of Drawings
[0020] [図 1]本発明の光子検出装置及びアフターパルス雑音抑圧法の説明図である。  FIG. 1 is an explanatory diagram of a photon detection device and an after-pulse noise suppression method of the present invention.
[図 2]本発明の光子検出装置による光子検出の説明図である。  FIG. 2 is an explanatory diagram of photon detection by the photon detection device of the present invention.
[図 3]本発明の光子検出装置によるアフターパルス雑音発生確率の説明図である。 圆 4]非特許文献 1を説明するための光子検出装置の説明図である。  FIG. 3 is an explanatory diagram of an after-pulse noise occurrence probability by the photon detection device of the present invention.圆 4] is an explanatory view of a photon detection device for explaining Non-Patent Document 1.
[図 5]非特許文献 3を説明するための光子検出装置の説明図である。  FIG. 5 is an explanatory diagram of a photon detection device for explaining Non-Patent Document 3.
[図 6]非特許文献 3を説明するための光子検出の説明図である。  FIG. 6 is an explanatory diagram of photon detection for explaining Non-Patent Document 3.
[図 7]非特許文献 7を説明するための光子検出装置の説明図である。  FIG. 7 is an explanatory diagram of a photon detection device for explaining Non-Patent Document 7.
[図 8]非特許文献 8を説明するための光子検出装置の説明図である。  FIG. 8 is an explanatory diagram of a photon detection device for explaining Non-Patent Document 8.
符号の説明  Explanation of symbols
[0021] 1 アバランシェフオトダイオード 2 直流電圧発生器 [0021] 1 Avalanche photodiode 2 DC voltage generator
3 パルス発生器  3 Pulse generator
4 バイアスティ  4 Bias tee
5、 7 抵抗器  5, 7 resistor
6 波高弁別器  6 Wave height discriminator
8 コンデンサー  8 Condenser
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0022] 本発明の基本的な実施の形態について以下詳細に説明する。 [0022] A basic embodiment of the present invention will be described in detail below.
本発明の光子検出装置は、基本的に、アバランシェフオトダイオードを受光素子と する光子検出手段と、該ァバランシェフオトダイオードに降伏電圧よりも低い直流電 圧を印加する直流電圧発生器と、ゲート信号 (電圧パルス）が出力されているときに のみ和電圧が降伏電圧を越えるようにした電圧パルス発生器と、和電圧を作成する バイアスティと、放電パルスの有無により光子検出を行う波高弁別器とから光子検出 装置を構成する。  The photon detection device of the present invention basically includes a photon detection means using an avalanche photodiode as a light receiving element, a DC voltage generator for applying a DC voltage lower than a breakdown voltage to the avalanche photodiode, and a gate signal ( A voltage pulse generator that causes the sum voltage to exceed the breakdown voltage only when a voltage pulse is output, a bias tee that creates the sum voltage, and a wave height discriminator that performs photon detection based on the presence or absence of a discharge pulse. Construct a photon detector.
また、本発明の光子検出方法は、基本原理となるアフターパルス雑音抑圧法を含 む光子検出方法装置であり、前記直流電圧発生器により前記直流電圧を前記アバ ランシェフオトダイオードの降伏電圧よりも低めに設定する手順 a、光子到着予定時刻 に前記パルス発生器カゝら発生する狭幅の電圧パルスをバイアスティ経由で重畳し、 前記直流電圧と前記電圧ノ ルスカ なる和電圧を前記アバランシェフオトダイオード に印加する手順 b、からなる。  Further, the photon detection method of the present invention is a photon detection method device including an after-pulse noise suppression method as a basic principle, wherein the DC voltage is set to be lower than the breakdown voltage of the avalanche photodiode by the DC voltage generator. A) superimposing a narrow-width voltage pulse generated by the pulse generator via a bias tee at the expected photon arrival time, and applying the sum of the DC voltage and the voltage norska to the avalanche photodiode. The procedure consists of applying b.
[0023] 光子が検出される場合に、アバランシェフオトダイオード内部で電子正孔のなだれ 増幅が起き、アバランシェフオトダイオードが低抵抗器として機能する。光子が検出さ れな力つた場合に、なだれ増幅が起きず、アバランシェフオトダイオードがコンデンサ 一として機能する。本発明では、アバランシェフオトダイオードが低抵抗器として機能 しているか、コンデンサ一として機能しているかを、放電パルスの大小で判別し、光子 検出を行う。具体的には、光子が検出された場合に発生する放電パルスと比較して 光子が検出されな力つた場合に発生する放電パルスが著しく小さいことに着目し、光 子が検出された場合に発生する小さな放電パルスに対してのみ波高弁別器力 の 出力が無となるように予めしきい値を設定する。この結果、光子が検出されな力つた 場合に波高弁別器カゝら電圧パルスが発生し、光子が検出された場合に前記波高弁 別器からの出力が無となる。 When a photon is detected, avalanche photo diode avalanche amplification occurs inside the avalanche photodiode, and the avalanche photodiode functions as a low resistor. If no photon is detected, no avalanche amplification occurs and the avalanche photodiode functions as a capacitor. In the present invention, whether the avalanche photodiode functions as a low resistor or as a capacitor is determined by the magnitude of the discharge pulse, and photon detection is performed. Specifically, we focused on the fact that the discharge pulse generated when a photon was not detected and the force applied was significantly smaller than the discharge pulse generated when a photon was detected. Of the pulse height discriminator power only for small discharge pulses A threshold is set in advance so that the output is nil. As a result, when a photon is not detected and a force is applied, a voltage pulse is generated from the pulse height discriminator, and when a photon is detected, there is no output from the pulse height discriminator.
実施例 1  Example 1
[0024] 図 1は本発明の光子検出手段を備えた光子検出装置の構成図である。図 1の光子 検出装置は、受光素子となるアバランシェフオトダイオード 1、該ァバランシェフオトダ ィオードに降伏電圧よりも低い直流電圧を印可する直流電圧発生器 2、ゲート信号（ 電圧パルス）を出力するパルス発生器 3、和電圧を作成するバイアスティ 4、充電電流 パルスを電圧変化に変換する抵抗器 5、充電電圧パルスの有無を判別する波高弁 別器 6、インピーダンス整合に必要な抵抗器 7及びコンデンサー 8からなる。光子検 出手段は、アバランシェフオトダイオードのなだれ増幅時の導通状態と不導通状態を 電圧変化または電流変化として検出できるようにする手段であり、実施例の場合、ァ ノ ランシェフオトダイオードの陽極に抵抗器 5を接続し、アバランシェフオトダイオード の陰極と前記抵抗器 5の接地端の間に抵抗器 7とコンデンサー 8の直列回路を接続 して構成する。  FIG. 1 is a configuration diagram of a photon detection device provided with the photon detection means of the present invention. The photon detector of FIG. 1 includes an avalanche photodiode 1 serving as a light receiving element, a DC voltage generator 2 for applying a DC voltage lower than a breakdown voltage to the avalanche photodiode, and a pulse for outputting a gate signal (voltage pulse). Generator 3, bias tee for creating sum voltage 4, resistor 5 for converting charging current pulse to voltage change, wave height discriminator 6 for judging presence or absence of charging voltage pulse 6, resistor 7 necessary for impedance matching, and capacitor Consists of eight. The photon detection means is a means for detecting a conduction state and a non-conduction state during avalanche amplification of an avalanche photodiode as a voltage change or a current change. And a series circuit of a resistor and a capacitor connected between the cathode of the avalanche photodiode and the ground terminal of the resistor.
[0025] 光子は予め設定した光子到着予定時刻にアバランシェフオトダイオード 1に入射さ れる。また、電圧パルス発生器 2から発生するゲート信号は光子到着予定時刻付近 でアバランシェフオトダイオード 1に印加され、和電圧がアバランシェフオトダイオード 1の降伏電圧を超過する範囲が光子到着予定時刻付近に限定される。すなわち、和 電圧が降伏電圧を超過する時間を限定し、光子検出による電子正孔のなだれ増幅 の発生時間と規模を制限する。これにより、アフターパルスの発生を抑制できる。  A photon is incident on the avalanche photodiode 1 at a preset scheduled photon arrival time. The gate signal generated from the voltage pulse generator 2 is applied to the avalanche photodiode 1 near the estimated photon arrival time, and the range in which the sum voltage exceeds the breakdown voltage of the avalanche photodiode 1 is limited to near the expected photon arrival time. You. In other words, the time during which the sum voltage exceeds the breakdown voltage is limited, and the time and scale of avalanche amplification of electron holes by photon detection are limited. Thereby, generation of an after pulse can be suppressed.
[0026] 図 1の構成は、従来例で示した図 5と波高弁別器を除いた構成が同じであるが、以 下のように、本発明ではアバランシェフオトダイオード 1の放電パルスを検知するため にこの構成を採用する。本発明による光子検出は、なだれ増幅を検知して光子検出 を行う従来技術とは全く異なる。尚、図 1に二本の同軸ケーブルが記載されているが 、非特許文献 7と異なり、長さや損失を完全に一致させる必要はない。  The configuration of FIG. 1 is the same as that of FIG. 5 shown in the conventional example except for the wave height discriminator. However, in the present invention, the configuration of FIG. 1 is for detecting a discharge pulse of the avalanche photodiode 1. This configuration is adopted. Photon detection according to the present invention is completely different from the prior art in which avalanche amplification is detected to perform photon detection. Although two coaxial cables are shown in FIG. 1, unlike the non-patent document 7, it is not necessary to completely match the length and the loss.
また、波高弁別器のしき 、値をなだれ増幅が無 、ときの放電パルスの頂点電位とな だれ増幅が有るときの放電パルスの頂点電位の間の任意の値に設定し、電圧パルス の立ち下がり位置でアバランシェフオトダイオードが発生する放電パルスを波高弁別 器に入力し、しきい値を超える放電パルスに対してのみ、波高弁別器から電圧パルス が出力されるように構成する。 Also, the threshold of the wave height discriminator is set to an arbitrary value between the top potential of the discharge pulse when avalanche amplification is not performed and the apex potential of the discharge pulse when avalanche amplification is performed, and a voltage pulse is set. The pulse generated by the avalanche photodiode at the falling edge of the pulse is input to the pulse height discriminator, and the voltage pulse is output from the pulse height discriminator only for the discharge pulse exceeding the threshold.
(動作）  (motion)
[0027] 図 2に該光子検出装置を動作させたときに抵抗器 5の両端で観測される電圧変化 の一例を示す。この電圧が波高弁別器 6の入力信号となる。図 2の上段は、光子検出 によりなだれ増幅が発生した場合、下段は光子検出がなされず、なだれ増幅が起こ らなかった場合である。図 2の下段では、アバランシェフオトダイオード 1がコンデンサ 一として機能するために正符号をもつ充電パルス (パルス C)と負符号を持つ放電パ ルス (パルス D)が観測されている。他の振動成分はインピーダンス不整合による雑音 であり、光子検出とは無関係である。  FIG. 2 shows an example of a voltage change observed at both ends of the resistor 5 when the photon detection device is operated. This voltage is the input signal of the wave height discriminator 6. The upper part of Fig. 2 shows the case where avalanche amplification occurred due to photon detection, and the lower part shows the case where no avalanche amplification occurred without photon detection. In the lower part of Fig. 2, a charge pulse with a positive sign (pulse C) and a discharge pulse with a negative sign (pulse D) are observed because the avalanche photodiode 1 functions as a capacitor. The other vibration components are noise due to impedance mismatch and have nothing to do with photon detection.
[0028] これに対して、図 2の上段では、正符号をもつ充電パルス（パルス A)は観測されて いるが、負符号を持つ放電パルス (パルス B)が非常に小さくなつている。これは、光 子検出によりなだれ増幅が起き、アバランシェフオトダイオード 1が低抵抗器として機 能し、コンデンサ一として機能していないことの証である。本発明では、アバランシェ フォトダイオード 1が低抵抗器として機能している力 コンデンサ一として機能している かを放電パルス（図 2のパルス B、 D)の有無により判定し、光子検出を行うものであり 、従来行なわれてきた、なだれ増幅による電流変化を抵抗器 5で電圧変換した後、光 子検出を行う方法 (図 6参照)とは異なる。  [0028] On the other hand, in the upper part of FIG. 2, a charge pulse (pulse A) having a positive sign is observed, but a discharge pulse (pulse B) having a negative sign is extremely small. This is a proof that avalanche photodiode 1 functions as a low resistor and does not function as a capacitor, due to avalanche amplification caused by photon detection. In the present invention, it is determined whether or not the avalanche photodiode 1 is functioning as a force capacitor that functions as a low resistor based on the presence or absence of a discharge pulse (pulses B and D in FIG. 2), and photon detection is performed. This is different from the conventional method in which a current change due to avalanche amplification is converted into a voltage by the resistor 5 and then photons are detected (see FIG. 6).
[0029] 本発明では、波高弁別器 6のしきい値を図 2に示すような位置に設定する。この結 果、光子が検出されな力つた場合に波高弁別器 6から電圧ノルスが発生し、光子が 検出された場合に波高弁別器 6からの出力が無となることで、光子検出の有無を判 断できる。図 2の上段では、光子検出によりなだれが発生しているが、なだれの規模 が充電パルス (パルス C)の大きさと比較して非常に小さく図中ではその発生を確認 することができな 、。アフターパルス雑音はなだれ増幅の規模に比例して増大するた め、充電パルス (パルス C)と比較して非常に小さいなだれ規模で光子検出ができる 本方式はアフターパルス雑音抑圧に極めて有効である。  In the present invention, the threshold value of the wave height discriminator 6 is set to a position as shown in FIG. As a result, when a photon is not detected and a force is applied, a voltage norm is generated from the wave height discriminator 6, and when a photon is detected, the output from the wave height discriminator 6 is nil. It can be determined. In the upper part of Fig. 2, avalanche occurs due to photon detection, but the size of the avalanche is very small compared to the magnitude of the charging pulse (pulse C), and it cannot be confirmed in the figure. Since afterpulse noise increases in proportion to the avalanche amplification scale, photons can be detected with a very small avalanche scale compared to the charge pulse (pulse C). This method is extremely effective in suppressing afterpulse noise.
[0030] 図 3にアフターパルス雑音の発生確率を示す。縦軸は百分率 (％)で示され、横軸 が経過時間 s)を示している。一般に、アフターパルスの発生は時間の経過ととも に減少する。図中の黒丸が本発明による実験結果、黒丸は図 6で示した光誘起によ るなだれ増幅電流を電圧変化として検出した場合のアフターパルス発生確率である 。図中の白丸では、ゲートを Insに設定している。白丸では、図 6に示す通り、なだれ 増幅を充電パルスより大きく成長させるために、幅の長い（2ns)ゲートを使用した。尚 、図 3の測定では両者とも、繰り返し周波数は、 5MHz、量子効率は、 15%付近にあ り、暗計数率は 5 X 10—5程度である。前述の通り、本方式では充電パルスと比較して 非常に小さいなだれ規模で光子検出を行うことが可能である。これに対して、従来例 の図 6では、なだれ増幅の規模が充電パルスと比較して大きい。アフターパルス雑音 はなだれ増幅の規模に比例して増大するため、充電パルス（図 2、パルス A)と比較し てなだれ増幅の規模が非常に小さい状態で光子検出ができる本方式の有効性が図 3の測定比較結果より確認された。 FIG. 3 shows the probability of occurrence of after-pulse noise. The vertical axis is shown in percentage (%), and the horizontal axis is Indicates elapsed time s). In general, the occurrence of afterpulses decreases with time. The black circles in the figure indicate the experimental results according to the present invention, and the black circles indicate the after-pulse generation probability when the photoinduced avalanche amplification current shown in FIG. 6 is detected as a voltage change. In the white circles in the figure, the gate is set to Ins. In the open circles, a long (2 ns) gate was used to grow the avalanche amplification beyond the charge pulse, as shown in Figure 6. Incidentally, both the measurement of FIG. 3, the repetition frequency is 5 MHz, quantum efficiency, Ri near near 15%, the dark count rate is about 5 X 10- 5. As described above, this method can detect photons with an avalanche size that is very small compared to the charging pulse. On the other hand, in FIG. 6 of the conventional example, the avalanche amplification is larger than the charging pulse. Since afterpulse noise increases in proportion to the size of the avalanche amplification, the effectiveness of this method, which can detect photons in a state where the avalanche amplification is very small compared to the charging pulse (pulse A in Fig. 2), is demonstrated. It was confirmed from the measurement comparison results of 3.
本発明の光子検出装置および光子検出方法によれば、原理的に、光子検出動作 を高速ィ匕することができるようになる。このため、量子暗号を用いた暗号通信の分野 において、鍵生成率を改善することができる。現状では、繰り返し周波数 10MHzに 対して鍵配布プロトコル B92を用い、光ファイバ一長 10. 5kmで鍵生成率 45kbitZ 秒を達成している。  According to the photon detection device and the photon detection method of the present invention, the photon detection operation can be performed at high speed in principle. Therefore, the key generation rate can be improved in the field of cryptographic communication using quantum cryptography. At present, a key generation rate of 45 kbitZ seconds has been achieved with an optical fiber length of 10.5 km using a key distribution protocol B92 for a repetition frequency of 10 MHz.
これに伴って、今までは、その速度に制限があつたため、 Vernam暗号の作成が困 難であつたが、本発明の光子検出装置および光子検出方法によれば Vemam暗号 と量子暗号を併用した暗号通信が可能になる。 Along with this, it was difficult to create the Vernam cipher because of the speed limitation, but according to the photon detecting device and the photon detecting method of the present invention, the Vemam cipher and the quantum cipher were used together. Encrypted communication becomes possible.

Claims

請求の範囲 The scope of the claims
[1] アバランシェフオトダイオードを受光素子とする光子検出手段と、アバランシェフオト ダイオードに電圧を印加するバイアスティと、前記バイアスティに直流電圧をバイアス 電圧として印加する直流電圧発生器と、前記バイアスティにパルス電圧を印加し光子 検出予定時刻でのみ前記検出手段を動作させる電圧パルス発生器と、光子が検出 されたカゝ否かを判定する波高弁別器で構成され、前記直流電圧発生器により前記直 流電圧を前記アバランシェフオトダイオードの降伏電圧よりも低めに設定し、光子到 着予定時刻に前記パルス発生器カゝら発生する狭幅の電圧パルスをバイアスティ経由 で重畳し、前記直流電圧と前記電圧パルス力 なる和電圧を前記アバランシェフオト ダイオードに印加するように構成したことを特徴とする光子検出装置。  [1] Photon detection means using an avalanche photodiode as a light receiving element, a bias tee for applying a voltage to the avalanche photodiode, a DC voltage generator for applying a DC voltage to the bias tee as a bias voltage, A voltage pulse generator that applies a pulse voltage to operate the detection means only at the scheduled photon detection time; and a wave height discriminator that determines whether or not a photon is detected. The current voltage is set lower than the breakdown voltage of the avalanche photodiode, and a narrow voltage pulse generated from the pulse generator is superimposed at a scheduled time of photon arrival via a bias tee. A light pulse characterized in that a sum voltage of a voltage pulse force is applied to the avalanche photodiode. Child detection device.
[2] 請求項 1記載の光子検出装置において、前記直流電圧を前記のアバランシェフオト ダイオードの降伏電圧よりも低めに設定し、前記電圧パルス発生器カゝら出力される電 圧パルスを重畳することにより、前記和電圧が前記降伏電圧を超過する時間を限定 し、光子検出による電子正孔のなだれ増幅の発生時間と規模を制限することを特徴 とする光子検出装置。  2. The photon detection device according to claim 1, wherein the DC voltage is set lower than a breakdown voltage of the avalanche photodiode, and a voltage pulse output from the voltage pulse generator is superimposed. The photon detection device is characterized in that the time during which the sum voltage exceeds the breakdown voltage is limited, thereby limiting the time and scale of avalanche amplification of electron holes caused by photon detection.
[3] 請求項 2記載の光子検出装置において、前記波高弁別器のしきい値をなだれ増幅 が無いときの放電パルスの頂点電位となだれ増幅が有るときの放電パルスの頂点電 位の間の任意の値に設定し、前記電圧パルスの立ち下がり位置で前記アバランシェ フォトダイオードが発生する放電パルスを前記波高弁別器に入力し、前記しき 、値を 超える前記放電パルスに対してのみ、前記波高弁別器力 電圧パルスが出力される ように構成したことを特徴とする光子検出装置。  [3] The photon detection device according to claim 2, wherein the threshold value of the wave height discriminator is any value between a peak potential of a discharge pulse when no avalanche amplification is performed and a peak potential of a discharge pulse when avalanche amplification is performed. The discharge pulse generated by the avalanche photodiode at the falling position of the voltage pulse is input to the pulse height discriminator, and only for the discharge pulse exceeding the threshold value, the pulse height discriminator is set. A photon detection device configured to output a force voltage pulse.
[4] 請求項 1ないし 3のいずれか 1項記載の光子検出装置において、光子が検出され たときに、同記載のアバランシェフオトダイオード内部で電子正孔のなだれ増幅が発 生し、アバランシェフオトダイオードが低抵抗器として機能するように構成したことを特 徴とする光子検出装置。  [4] In the photon detection device according to any one of claims 1 to 3, when a photon is detected, avalanche amplification of an electron hole occurs inside the avalanche photodiode and the avalanche photodiode. A photon detection device characterized in that it is configured to function as a low resistor.
[5] 請求項 1ないし 3のいずれか 1項記載の光子検出装置において、光子が検出され な力つたときに、なだれ増幅が発生せず、前記アバランシェフオトダイオードがコンデ ンサ一として機能するように構成したことを特徴とする光子検出装置。 [5] The photon detection device according to any one of [1] to [3], wherein no avalanche amplification occurs when a photon is not detected and the avalanche photodiode functions as a capacitor. A photon detection device characterized by comprising.
[6] 請求項 1ないし 5のいずれか 1項記載の光子検出装置において、光子が検出され な力つたときに発生する放電パルスに対して、前記波高弁別器から光子非検出を意 味する電圧パルスが発生するように予めしき ヽ値が設定されて ヽることを特徴とする 光子検出装置。 [6] The photon detection device according to any one of claims 1 to 5, wherein the pulse height discriminator detects non-photon detection with respect to a discharge pulse generated when a photon is not detected. A photon detection device wherein a threshold value is set in advance so that a pulse is generated.
[7] 請求項 1ないし 5のいずれか 1項記載の光子検出装置において、光子が検出され たときに発生する放電パルスはアバランシェフオトダイオードが低抵抗器として機能 するために、光子が検出されな力 たときに発生する放電パルスと比較して小さくなり 、前記の小さな放電パルスに対してのみ前記波高弁別器力 の出力が無となるよう に予めしきい値が設定されていることを特徴とする光子検出装置。  [7] In the photon detection device according to any one of claims 1 to 5, the discharge pulse generated when a photon is detected is not detected because the avalanche photodiode functions as a low resistor. The threshold value is set in advance so that the output value of the pulse height discriminator force is negligible only for the small discharge pulse as compared with a discharge pulse generated when the force is applied. Photon detector.
[8] 請求項 1ないし 5のいずれか 1項記載の光子検出装置において、光子が検出され な力つたときに前記波高弁別器力 電圧パルスが発生し、光子が検出されたときに 前記波高弁別器からの出力が無となることで、光子検出の有無を判断することを特 徴とする光子検出装置。  [8] The photon detection device according to any one of claims 1 to 5, wherein the pulse height discriminator force voltage pulse is generated when a photon is not detected and the photon is detected. A photon detector characterized in that the absence of output from the detector determines the presence or absence of photon detection.
[9] アバランシェフオトダイオードを受光素子とする光子検出手段と、アバランシェフオト ダイオードに電圧を印加するバイアスティと、前記バイアスティに直流電圧をバイアス 電圧として印加する直流電圧発生器と、前記バイアスティにパルス電圧を印加し光子 検出予定時刻でのみ前記検出手段を動作させる電圧パルス発生器と、光子が検出 された力否かを判定する波高弁別器力 なる装置において、  [9] Photon detection means using an avalanche photodiode as a light receiving element, a bias tee for applying a voltage to the avalanche photodiode, a DC voltage generator for applying a DC voltage to the bias tee as a bias voltage, A voltage pulse generator that applies a pulse voltage to operate the detection means only at the scheduled photon detection time, and a device that determines whether or not a photon is detected by a pulse height discriminator.
前記直流電圧発生器により前記直流電圧を前記アバランシェフオトダイオードの降 伏電圧よりも低めに設定する手順 b、  A step b of setting the DC voltage by the DC voltage generator to be lower than the breakdown voltage of the avalanche photodiode;
光子到着予定時刻に前記パルス発生器カゝら発生する狭幅の電圧パルスをバイアス ティ経由で重畳し、前記直流電圧と前記電圧パルスからなる和電圧を前記アバラン シェフオトダイオードに印加する手順 c、  A step c) of superimposing a narrow-width voltage pulse generated by the pulse generator card at a scheduled photon arrival time via a bias tee and applying a sum voltage composed of the DC voltage and the voltage pulse to the avalanche chef photodiode.
からなることを特徴とする光子検出方法。  A photon detection method characterized by comprising:
[10] 前記請求項 9記載の光子検出方法において、 [10] In the photon detection method according to claim 9,
前記手順 bの前に、前記波高弁別器のしきい値をなだれ増幅が無いときの放電パ ルスの頂点電位となだれ増幅が有るときの放電パルスの頂点電位の間の任意の値 に設定し、前記電圧パルスの立ち下がり位置で前記アバランシェフオトダイオードが 発生する放電パルスを前記波高弁別器に入力し、前記しき 、値を超える前記放電パ ルスに対してのみ、前記波高弁別器力 電圧パルスが出力されるように設定する手 順 aを設けたことを特徴とする光子検出方法。 Before the step b, the threshold of the pulse height discriminator is set to an arbitrary value between the top potential of the discharge pulse when no avalanche amplification is performed and the top potential of the discharge pulse when avalanche amplification is performed; At the falling position of the voltage pulse, the avalanche photodiode A step a of inputting a generated discharge pulse to the pulse height discriminator and setting the pulse height discriminator power voltage pulse to be output only for the discharge pulse exceeding the threshold value is provided. A photon detection method comprising:
PCT/JP2004/013063 2003-09-17 2004-09-08 Photon detecting apparatus and photon detecting method WO2005029017A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2003-325226 2003-09-17
JP2003325226 2003-09-17
JP2004-132270 2004-04-27
JP2004132270A JP4724874B2 (en) 2003-09-17 2004-04-27 Photon detection apparatus and photon detection method

Publications (1)

Publication Number Publication Date
WO2005029017A1 true WO2005029017A1 (en) 2005-03-31

Family

ID=34380315

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2004/013063 WO2005029017A1 (en) 2003-09-17 2004-09-08 Photon detecting apparatus and photon detecting method

Country Status (2)

Country Link
JP (1) JP4724874B2 (en)
WO (1) WO2005029017A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2475235A (en) * 2009-11-09 2011-05-18 Toshiba Res Europ Ltd A photon detector
CN115032913A (en) * 2022-05-25 2022-09-09 北京邮电大学 Avalanche photodiode simulation circuit and simulation model

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5326081B2 (en) * 2006-03-06 2013-10-30 学校法人日本大学 Optical communication wavelength band high-speed single photon detector
JP2008282922A (en) * 2007-05-09 2008-11-20 Hochiki Corp Photoelectric conversion device
GB2456149B (en) 2008-01-03 2012-05-30 Toshiba Res Europ Ltd A photon detection system and a method of photon detection
EP2333843A4 (en) 2008-09-12 2016-12-07 Mitsubishi Electric Corp Photon detector
JP5383327B2 (en) * 2009-06-08 2014-01-08 三菱電機株式会社 Photon detector, quantum cryptography communication device using the same, and photon detection method
KR101395330B1 (en) 2012-04-06 2014-05-16 에스케이텔레콤 주식회사 Single photon detector, photon number resolving detector and detecting method thereof
JP7309332B2 (en) * 2018-08-28 2023-07-18 パイオニア株式会社 Control device, sensor device, control method and program

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5532474A (en) * 1993-12-17 1996-07-02 Eg&G Limited Active quench circuit and reset circuit for avalanche photodiode
JP2003243691A (en) * 2002-02-15 2003-08-29 Japan Science & Technology Corp Photon detector and quantum communication device and quantum computer comprising it
JP2003282933A (en) * 2002-03-27 2003-10-03 National Institute Of Advanced Industrial & Technology Single photon detector and method of removing after pulse thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5532474A (en) * 1993-12-17 1996-07-02 Eg&G Limited Active quench circuit and reset circuit for avalanche photodiode
JP2003243691A (en) * 2002-02-15 2003-08-29 Japan Science & Technology Corp Photon detector and quantum communication device and quantum computer comprising it
JP2003282933A (en) * 2002-03-27 2003-10-03 National Institute Of Advanced Industrial & Technology Single photon detector and method of removing after pulse thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
YOSHIZAWA A. ET AL.: "A 1550nm Single-Phonon Detector for Fiber-Optic Quantum Cryptography.", NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY (OYOBUTSURI), vol. 72, no. 2, 10 February 2003 (2003-02-10), pages 205 - 208, XP008041221 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2475235A (en) * 2009-11-09 2011-05-18 Toshiba Res Europ Ltd A photon detector
GB2475235B (en) * 2009-11-09 2014-01-08 Toshiba Res Europ Ltd A photon detector
US8841596B2 (en) 2009-11-09 2014-09-23 Kabushiki Kaisha Toshiba Quasi continuous photon detection system
CN115032913A (en) * 2022-05-25 2022-09-09 北京邮电大学 Avalanche photodiode simulation circuit and simulation model
CN115032913B (en) * 2022-05-25 2023-08-11 北京邮电大学 Avalanche photodiode simulation circuit and simulation model

Also Published As

Publication number Publication date
JP2005114712A (en) 2005-04-28
JP4724874B2 (en) 2011-07-13

Similar Documents

Publication Publication Date Title
JP5326081B2 (en) Optical communication wavelength band high-speed single photon detector
KR101740263B1 (en) Single photon detector in the near infrared using an InGaAs/InP avalanche photodiode operated with a bipolar rectangular gating signal.
JP5624524B2 (en) Photon detection photon detection system and method
CN110462415B (en) Burr signal detection circuit, safety chip and electronic equipment
KR101685494B1 (en) Apparatus for Detecting Single Photon and Method for the same
CN106940221B (en) Avalanche signal discrimination method and device and infrared single-photon detector
WO2005029017A1 (en) Photon detecting apparatus and photon detecting method
U’Ren et al. Characterization of the nonclassical nature of conditionally prepared single photons
CN102155998B (en) Fully-integrated high-speed single photon detecting system and detecting method
KR101395330B1 (en) Single photon detector, photon number resolving detector and detecting method thereof
Sarbazi et al. Detection statistics and error performance of SPAD-based optical receivers
US20220170786A1 (en) Single-photon detection apparatus and method
EP2189816B1 (en) Charge pulse detecting circuit
JP2006287307A (en) Photon detection circuit and noise elimination method
WO2023004610A1 (en) Laser radar ranging system
EP3780394A1 (en) Circuit arrangement and method for charge integration
JP2011226922A (en) Photon detector
KR101333806B1 (en) Method and apparatus for cancellation of transient voltage spike
EP4080352B1 (en) Random number generator, in particular truly random number generator of an improved type
CN114624678A (en) Front-end circuit of photoelectric detector, photoelectric detector array, laser radar and distance measuring method
KR101966652B1 (en) Method and Apparatus for Detecting Single Photon by Reverse Counting
Losev et al. Dead time duration and active reset influence on the afterpulse probability of InGaAs/InP SPAD based SPDs
CN218006253U (en) Laser driving device
Kolka et al. Modeling Output Signals of Solid-State Photomultiplier with Capacitive Coupling
CN117007196A (en) Single photon detector

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BW BY BZ CA CH CN CO CR CU CZ DK DM DZ EC EE EG ES FI GB GD GE GM HR HU ID IL IN IS KE KG KP KR LC LK LR LS LT LU LV MA MD MG MN MW MX MZ NA NI NO NZ OM PG PL PT RO RU SC SD SE SG SK SL SY TM TN TR TT TZ UA UG US UZ VC YU ZA ZM

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SZ TZ UG ZM ZW AM AZ BY KG MD RU TJ TM AT BE BG CH CY DE DK EE ES FI FR GB GR HU IE IT MC NL PL PT RO SE SI SK TR BF CF CG CI CM GA GN GQ GW ML MR SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase