CN113497705B - Polarization modulator, driving method and quantum key distribution system - Google Patents
Polarization modulator, driving method and quantum key distribution system Download PDFInfo
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- CN113497705B CN113497705B CN202010269137.2A CN202010269137A CN113497705B CN 113497705 B CN113497705 B CN 113497705B CN 202010269137 A CN202010269137 A CN 202010269137A CN 113497705 B CN113497705 B CN 113497705B
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- 229940125730 polarisation modulator Drugs 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 13
- 230000010287 polarization Effects 0.000 claims abstract description 69
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 16
- 229910052710 silicon Inorganic materials 0.000 claims description 16
- 239000010703 silicon Substances 0.000 claims description 16
- 230000000694 effects Effects 0.000 claims description 9
- 239000000758 substrate Substances 0.000 claims description 7
- 239000006185 dispersion Substances 0.000 claims description 6
- 230000003287 optical effect Effects 0.000 abstract description 16
- 230000010354 integration Effects 0.000 abstract description 11
- 238000002360 preparation method Methods 0.000 abstract description 9
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- 230000015572 biosynthetic process Effects 0.000 description 3
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- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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Abstract
The invention provides a polarization modulator, a driving method and a quantum key distribution system, which comprise a first-stage interference structure and a second-stage interference structure which are cascaded, wherein a bias phase shifter is arranged on one arm of the first-stage interference structure, and phase shifters are respectively arranged on two arms of the second-stage interference structure; a bias phase shifter configured to be driven by a direct current voltage, the phase shifter configured to drive a pulse voltage in a single-ended push-pull manner; the system integration level is greatly improved, and the cost of an optical system is reduced; the method solves the problem of unstable polarization state preparation under dynamic high-speed modulation, and reduces the number and driving voltage of dynamic driving circuits.
Description
Technical Field
The disclosure belongs to the technical field of quantum key distribution, and particularly relates to a polarization modulator, a driving method and a quantum key distribution system.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
Polarization encoded Quantum Key Distribution (QKD) systems are key distribution implemented with photon polarization states as information carriers. Photon polarization state preparation is critical in QKD systems. The accuracy and stability of photon polarization state preparation directly determine the long-term error rate and safety of a commercial QKD system.
According to the inventor, two photon polarization state preparation schemes are mainly included at present, one of which is to combine and connect classical discrete devices (polarization beam splitters, phase shifters, optical fibers, flanges and the like) by using the existing commercial quantum key distribution scheme, so as to construct the polarization modulator/module with the required functions. The polarization modulator/module manufactured by the scheme is huge and is not beneficial to integration. Is obviously affected by the ambient temperature and vibration, and has poor stability.
The other scheme is to adopt a silicon photon on-chip integration technology to realize the function of an optical system of a quantum key sending end. As shown in fig. 1: a two-stage mach-zehnder interferometer (MZ interferometer) structure is employed. The polarization modulator is formed by connecting two stages of MZ interferometers in series and is used for preparing a horizontal polarization state H, a vertical polarization state V, +45 DEG polarization state P and-45 DEG polarization state N. The existing QKD products all use pulsed light sources, which require that both phase shifters in a two-stage interference structure be driven with pulsed voltages. When the phase difference of the signal light in the first-stage interference structure is 0 and pi, the horizontal polarization state and the vertical polarization state are prepared correspondingly. On the premise that the phase difference of the two arms of the first stage is pi/2, the phase difference of the two arms of the second stage is 0 and pi, and the +45 DEG polarization state and the-45 DEG polarization state are prepared correspondingly. In QKD systems, signals of several hundred MHz and even GHz are typically employed. At such high frequency modulation, it is difficult for the drive to achieve a perfect phase difference. And pi/2 phase shift is in the middle position of the phase shift-power interference curve, the slope is maximum, the influence of phase shift jitter on the interference power output is larger, and the dependence of the polarization state modulation of the second-stage interference structure on the proportion of the light intensity of the upper arm and the lower arm of the second-stage interference structure is stronger. Therefore, slight deviation of the first-order modulation phase difference has very significant influence on the polarization state preparation of the second-order interference structure. Secondly, the scheme adopts two paths of independent dynamic driving circuits, and has high cost.
Disclosure of Invention
In order to solve the problems, the present disclosure provides a polarization modulator, a driving method and a quantum key distribution system, which greatly improves the system integration level and reduces the cost of an optical system; the method solves the problem of unstable polarization state preparation under dynamic high-speed modulation, and reduces the number and driving voltage of dynamic driving circuits.
According to some embodiments, the present disclosure employs the following technical solutions:
a polarization modulator is integrated on a silicon substrate and comprises a first-stage interference structure and a second-stage interference structure which are cascaded, wherein a bias phase shifter is arranged on one arm of the first-stage interference structure, and phase shifters are respectively arranged on two arms of the second-stage interference structure;
the bias phase shifter is configured to be driven by a direct voltage, and the phase shifter is configured to drive a pulse voltage in a single-ended push-pull manner.
In the technical scheme, firstly, all components are integrated on the silicon substrate, so that the problems of huge volume, poor stability and the like in a classical discrete device mode in the prior art are effectively solved, the integration level is greatly improved, and the cost of an optical system is also reduced.
And secondly, the phase shifter of the second-stage interference structure is driven by pulse driving voltage in a single-ended push-pull mode, one driving signal can be used for simultaneously driving the two-arm phase shifter, half-wave voltage is reduced, the chirp phenomenon of the modulator is reduced, and the bandwidth of the modulator is improved. The problem of in prior art the second mode existence must two way independent dynamic drive circuit, the cost is higher to influence greatly between the two-stage is solved.
As an alternative embodiment, the first-stage interference structure comprises a 1×2 beam splitter, a bias phase shifter and a 2×2 beam splitter, wherein the 1×2 beam splitter is used for dividing signal light into two beams in equal proportion, and the output ends of the 1×2 beam splitter are respectively connected with different input ends of the 2×2 beam splitter through waveguides, wherein the bias phase shifter is additionally arranged on the way.
The 2 x 2 beam splitter is used for converging two light signals and forming interference.
Alternatively, the bias phase shifter may be a thermally tuned phase shifter or a silicon-based phase shifter based on carrier dispersion effects.
Of course, in other alternative embodiments, other types of offset phase shifters may be substituted as the case may be or as desired.
As an alternative embodiment, the beam splitting ratio of the 1×2 beam splitter to the 2×2 beam splitter is 1:1.
As an alternative embodiment, the second-stage interference structure includes two phase shifters and a polarization synthesizer, where two output ends of the 2×2 beam splitter are respectively connected to one phase shifter, and two output ends of the two phase shifters are respectively connected to two input ends of the polarization synthesizer.
As an alternative implementation mode, a BIAS electrode is additionally arranged in the electrode structure of the modulator and is used for inputting a direct current BIAS signal so that the modulator works at a target BIAS point.
Alternatively, the phase shifter is a PN type phase shifter.
Further, the PN type phase shifter is a silicon-based phase shifter based on carrier dispersion effect, and the optional doping structure is PIN type or PN type.
Of course, in other alternative embodiments, other types of phase shifters may be substituted as the case may be or as desired.
Based on the driving method of the polarization modulator, the bias phase shifter in the first-stage interference structure is driven by adopting direct-current voltage, and the phase shifter of the second-stage interference structure is driven by adopting pulse driving voltage in a single-ended push-pull mode.
Specifically, the dynamic pulse voltage drives the two-arm phase shifter in a push-pull mode, so that the phase shifter modulates four phase differences to two paths of signal light, and the four paths of signal light are converged on the polarization beam combiner to synthesize a required polarization state: when the phase difference of the two-arm signal of the second-stage interference is 0, the synthetic polarization state is +45°; when the phase difference is pi/2, the synthesized polarization state is right-hand circular polarization; when the phase difference is pi, the synthetic polarization state is-45 degrees; when the phase difference is 3 pi/2, the synthetic polarization state is left-hand circular polarization.
A quantum key distribution system comprising the above-described polarization modulator.
Compared with the prior art, the beneficial effects of the present disclosure are:
the whole structure of the polarization modulator is monolithically integrated on the silicon substrate, so that the integration level is improved, the volume is reduced, and the input cost is also reduced.
One path of the first-stage interference structure is additionally provided with a bias phase shifter; driving the bias phase shifter by using a direct current voltage; the refractive index of the waveguide can be changed so as to play a role in modulating the phase difference of the two-arm optical signals; the light intensity distribution of the second-stage interference structure can be strictly and stably controlled; and the stability of the DC drive is much higher than that of the dynamic drive when preparing each polarization state.
The BIAS electrode is added on the basis of the electrode structure of the traditional modulator, and is used for inputting a direct-current BIAS signal, the modulator is driven in a single-ended push-pull mode, two phase shifters can be driven simultaneously by one pulse driving, compared with other modulation methods, the driving voltage amplitude can be obviously reduced when the same modulation depth is achieved, and a driving circuit is not added while the driving voltage is reduced.
The single-ended push-pull mode driving modulator can obviously reduce the influence of the chirp phenomenon on the modulator, improve the power stability of each prepared polarization state, reduce half-wave voltage and improve the bandwidth of the modulator.
The polarization modulator is used for a Quantum Key Distribution (QKD) system, can reduce the volume of the QKD optical system and greatly improves the integration level of the QKD system; the power stability of the optical signal is improved in the QKD system with high speed modulation, and the long-term error rate and the safety of the commercial quantum key distribution system are facilitated.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure.
FIG. 1 is a schematic diagram of a prior art structure employing a two-stage Mach-Zehnder interferometer of the present disclosure;
FIG. 2 is a schematic diagram of the structure of the polarization modulator of the present embodiment;
fig. 3 is a sectional structural view of the PN phase shifter of the present embodiment;
FIG. 4 is a schematic diagram of a second-stage interference structure of the present embodiment;
FIG. 5 is a diagram of the operational equivalent circuit of the second stage interferometric structure modulation of this embodiment.
Wherein: 1. 1×2 beam splitters, 2, offset phase shifters, 3, 2×2 beam splitters, 4, PN phase shifters, 5, PN phase shifters, 6, polarization combiners, 7, S electrodes, 8, BIAS electrodes, 9, GND electrodes.
The specific embodiment is as follows:
the disclosure is further described below with reference to the drawings and examples.
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments in accordance with the present disclosure. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, are merely relational terms determined for convenience in describing structural relationships of the various components or elements of the present disclosure, and do not denote any one of the components or elements of the present disclosure, and are not to be construed as limiting the present disclosure.
In the present disclosure, terms such as "fixedly coupled," "connected," and the like are to be construed broadly and refer to either a fixed connection or an integral or removable connection; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the terms in the disclosure may be determined according to circumstances, and should not be interpreted as limiting the disclosure, for relevant scientific research or a person skilled in the art.
As described in the background art, in the first existing solution, the existing commercial quantum key distribution solution adopts a discrete device to implement polarization modulation, so that the device is huge, power consumption is high, cost is high, system integration is difficult to implement, and system stability is poor. In the second conventional scheme, as shown in fig. 1, it is difficult to achieve a perfect phase difference in the driving under the high frequency modulation of the key distribution system. The first-stage modulation phase difference is slightly deviated, so that the second-stage interference structure polarization state preparation effect is obvious, at least two paths of independent dynamic driving circuits are needed, and the cost is high.
In order to solve the above-mentioned problems, the present disclosure proposes a highly stable polarization modulator integrated on a silicon substrate. The monolithic integration of discrete devices such as a phase shifter and a beam splitter in the traditional QKD system is realized on silicon base, so that the system integration level is greatly improved, and the cost of an optical system is reduced.
The invention also provides an electrode design structure and a driving method of the modulator, which can solve the problem of unstable polarization state preparation under dynamic high-speed modulation and reduce the number of dynamic driving circuits and driving voltage.
In order to make the technical solution for achieving the above object more clear to those skilled in the art, the following description is given by way of example.
Example 1
A high stability polarization modulator integrated on a silicon substrate includes a 1×2 beam splitter 1, a bias phase shifter 2, a 2×2 beam splitter 3, a PN type phase shifter 4, a PN type phase shifter 5, and a polarization synthesizing device 6.
As shown in fig. 2, a 1 x 2 beam splitter 1, a bias phase shifter 2 and a 2 x 2 beam splitter 3 together form a first order interference structure of the polarization modulator. The 1×2 beam splitter equally divides the signal light into two beams, and the two outlets are respectively connected with the two input ends of the 2×2 beam splitter 3 through optical waveguides.
In some embodiments, the split ratio of the 1 x 2 beam splitter and the 2 x 2 beam splitter is 1:1.
It should be noted that, since the 2×2 beam splitter 3 is a common part of the first-stage interference structure and the second-stage interference structure, in this embodiment, the first-stage interference structure and the second-stage interference structure each include the 2×2 beam splitter 3, but in the description of other embodiments, the 2×2 beam splitter 3 may be separately divided into a part of the first-stage interference structure or the second-stage interference structure, which are merely different in expression, and do not represent a difference in technical scheme or a difference in protection scope.
The TE mode signal light is split into two beams by the 1×2 beam splitter 1, and is input to the upper and lower arms of the first-stage interference structure respectively. One of which passes additionally through the offset phase shifter 2.
The offset phase shifter 2 is driven by direct current voltage, so that the refractive index of the waveguide can be changed, and the effect of modulating the phase difference of the two-arm optical signals is achieved. The two-arm optical signals with phase differences are converged and interfere at the 2 x 2 beam splitter.
As shown in fig. 3, the cross-sectional structure of the PN phase shifter includes p+, P, N, N + disposed in sequence, wherein the P, N portion is a ridge waveguide portion.
Wherein P+ and N+ are respectively P-type heavy doping and N-type heavy doping, and P, N is respectively P-type doping and N-type doping.
In this embodiment, the first-stage bias phase shifter is driven by a constant direct current signal, so that the light intensity distribution of the second-stage interference structure can be strictly and stably controlled. This embodiment reduces the need for one-way dynamic driving circuitry compared to the solution of preparing H, V, P, N. And the stability of the DC drive is much higher than that of the dynamic drive when preparing each polarization state.
In some embodiments, the bias phase shifter in the first-stage interference structure may be a thermally tuned phase shifter or a silicon-based phase shifter based on carrier dispersion effect.
Of course, this does not mean that the bias phase shifter can only be used in both types, but in other embodiments other phase shifters can be substituted.
As shown in fig. 4, the second-stage interference structure specifically includes: 2 x 2 beam splitter 3, PN type phase shifter 4, PN type phase shifter 5, polarization synthesizer 6, S electrode 7, BIAS electrode 8, GND electrode 9.
After the signal light is interfered by the 2 x 2 beam splitter 3, the signal light is output from the two light outlets respectively, and the PN phase shifter 4 and the PN phase shifter 5 are connected through the optical waveguide respectively. The two PN phase shifters are driven by dynamic pulse voltage and modulate the phase difference of the signal light of the upper arm and the lower arm. The signals are then converged by the polarization synthesis device 6 and the polarization states are synthesized. The polarization synthesis device 6 receives two paths of input optical signals, rotates the polarization state of one path of input signals by 90 degrees, keeps the other path unchanged, and performs polarization synthesis on the two paths of signals and outputs the signals.
Pulse driving voltage signal V S The BIAS electrode is used for enabling the modulator to work at a target BIAS point V by inputting the S electrode into the modulator BIAS . The GND electrode 9 is for switching in the GND signal.
The PN phase shifter 4 and the PN phase shifter 5 are controlled by a dynamic driving circuit, and a single-ended push-pull mode is adopted to drive the two-arm phase shifter simultaneously by a driving circuit.
As shown in fig. 5, in the ideal working equivalent circuit diagram, the diodes i and ii are respectively equivalent PN or PIN diodes formed by the doped regions of the phase shifters on the upper and lower arms of the second stage of the MZ interference structure, and the resistor iii is used for impedance matching of the input signal terminal.
The embodiment adds BIAS electrodes based on the conventional modulator electrode structure for inputting dc BIAS signals.
The signal electrode (S electrode) is arranged at one side of the two waveguides, and the driving electric signal is applied to the PN junction or the PIN junction through the signal electrode.
Pulse driving voltage signal V S And may be positive or negative. Can be formed with V BIAS To bias, the driving voltage is at-V S V/2 and V S Alternate push-pull drive between/2.
The dynamic driving voltage is input into the modulator through the S electrode, four pulse voltages are respectively issued, and the two-arm phase shifter is driven in a single-end push-pull mode, so that the phase shifter modulates four phase differences (0, pi/2, pi, 3 pi/2) onto two paths of signal lights. The desired polarization states are then combined and synthesized at a polarization combiner:
when the phase difference of the two-arm signal of the second-stage interference is 0, the synthetic polarization state is +45°; when the phase difference is pi/2, the synthesized polarization state is right-hand circular polarization; when the phase difference is pi, the synthetic polarization state is-45 degrees; when the phase difference is 3 pi/2, the synthetic polarization state is left-hand circular polarization.
The phase shifters are driven in a single-ended push-pull mode, one pulse is used for driving the two phase shifters, and compared with other modulation methods, the amplitude of the driving voltage can be obviously reduced when the same modulation depth is achieved.
The single-ended push-pull mode drives the modulator to significantly reduce the effect of chirp phenomena on the modulator. The dual-phase shifter is in series connection, so that the capacitance value is reduced, the transmission loss of a driving signal on a line wave electrode can be reduced, and the modulation bandwidth is improved.
In some embodiments, the PN type phase shifter is a silicon-based phase shifter based on carrier dispersion effect, and the optional doping structure is PIN type or PN type.
In the first embodiment, the bias phase shifter in the first-stage interference structure is driven by a direct-current voltage, so that polarization state preparation is more stable, the requirement of a dynamic driving circuit is reduced, the modulator of the second-stage interference structure is driven by a pulse driving voltage in a single-ended push-pull mode, the two-arm phase shifter can be driven by a driving signal at the same time, half-wave voltage is reduced, chirp of the modulator is reduced, and the bandwidth of the modulator is improved. The four polarization states of +45° polarization state, right-hand circular polarization state, -45 ° polarization state and left-hand circular polarization state can be prepared, and the application range is wide.
Example two
A Quantum Key Distribution (QKD) system comprising a silicon-based integrated polarization modulator provided in accordance with embodiment one.
In the quantum key distribution system provided by the embodiment, the polarization modulator is integrated on the silicon substrate, so that the volume of the QKD optical system is reduced, and the integration level of the QKD system is greatly improved.
While reducing the cost of the optical system.
The bias phase shifter in the first-stage interference structure is driven by direct-current voltage, so that the light intensity proportion of two arm signals in the second-stage interference structure can be strictly controlled, and the polarization angle stability of each prepared polarization state is improved. And the requirement of one path of dynamic driving circuit is reduced, and the cost of the peripheral driving circuit is reduced.
The second-stage interference structure is driven by adopting a single-end push-pull mode, four polarization states can be prepared, only one driving circuit is needed, driving voltage is reduced, and meanwhile, the driving circuit is not increased. And the influence of the chirp phenomenon on the modulator is reduced, and the power stability of the optical signal is further improved in a QKD system with high-speed modulation.
The foregoing description of the preferred embodiments of the present disclosure is provided only and not intended to limit the disclosure so that various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
While the specific embodiments of the present disclosure have been described above with reference to the drawings, it should be understood that the present disclosure is not limited to the embodiments, and that various modifications and changes can be made by one skilled in the art without inventive effort on the basis of the technical solutions of the present disclosure while remaining within the scope of the present disclosure.
Claims (8)
1. A polarization modulator integrated on a silicon substrate comprising cascaded first-order and second-order interference structures, characterized by: a bias phase shifter is arranged on one arm of the first-stage interference structure, and phase shifters are respectively arranged on two arms of the second-stage interference structure;
the bias phase shifter is configured to be driven by a direct current voltage, and the phase shifter is configured to drive a pulse voltage in a single-ended push-pull manner;
the first-stage interference structure comprises a 1X 2 beam splitter, a bias phase shifter and a 2X 2 beam splitter, wherein the 1X 2 beam splitter is used for dividing signal light into two beams in equal proportion, the output ends of the 1X 2 beam splitter are respectively connected with different input ends of the 2X 2 beam splitter through waveguides, and the bias phase shifter is additionally arranged on the way;
the second-stage interference structure comprises two phase shifters and a polarization synthesizer, wherein two output ends of the 2X 2 beam splitter are respectively connected with one phase shifter, and output ends of the two phase shifters are respectively connected with two input ends of the polarization synthesizer.
2. A polarization modulator according to claim 1, wherein: the bias phase shifter is a thermally tuned phase shifter or a silicon-based phase shifter based on carrier dispersion effect.
3. A polarization modulator according to claim 1, wherein: the beam splitting ratio of the 1×2 beam splitter to the 2×2 beam splitter is 1:1.
4. A polarization modulator according to any one of claims 1 to 3, characterized in that: and a BIAS electrode is additionally arranged in the electrode structure of the modulator and is used for inputting a direct current BIAS signal so that the modulator works at a target BIAS point.
5. A polarization modulator according to any one of claims 1 to 3, characterized in that: the phase shifter is a PN phase shifter;
the PN type phase shifter is a silicon-based phase shifter based on carrier dispersion effect, and the doping structure is PIN type or PN type.
6. A driving method of the polarization modulator according to any one of claims 1 to 5, characterized by: the bias phase shifter in the first-stage interference structure is driven by direct-current voltage, and the phase shifter of the second-stage interference structure is driven by pulse driving voltage in a single-ended push-pull mode.
7. The driving method as set forth in claim 6, wherein: the dynamic pulse voltage drives the two-arm phase shifter in a single-end push-pull mode, so that the phase shifter modulates four phase differences to two paths of signal light, and the four paths of signal light are converged on the polarization beam combiner to synthesize a required polarization state:
when the phase difference of the two-arm signal of the second-stage interference is 0, the synthetic polarization state is +45°; when the phase difference is pi/2, the synthesized polarization state is right-hand circular polarization; when the phase difference is pi, the synthetic polarization state is-45 degrees; when the phase difference is 3 pi/2, the synthetic polarization state is left-hand circular polarization.
8. A quantum key distribution system, characterized by: comprising a polarization modulator according to any of claims 1-5.
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| CN207977967U (en) * | 2017-12-29 | 2018-10-16 | 浙江九州量子信息技术股份有限公司 | A kind of polarization encoder QKD system based on silicon substrate integrated chip |
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| CN110601752A (en) * | 2019-08-16 | 2019-12-20 | 武汉光迅科技股份有限公司 | Chirp measuring device and method, computer readable storage medium |
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