KR20170062953A - Multi-channel terahertz time domain spectroscopy system - Google Patents

Multi-channel terahertz time domain spectroscopy system Download PDF

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Publication number
KR20170062953A
KR20170062953A KR1020150168784A KR20150168784A KR20170062953A KR 20170062953 A KR20170062953 A KR 20170062953A KR 1020150168784 A KR1020150168784 A KR 1020150168784A KR 20150168784 A KR20150168784 A KR 20150168784A KR 20170062953 A KR20170062953 A KR 20170062953A
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South Korea
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terahertz wave
optical
sample
terahertz
channel
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KR1020150168784A
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Korean (ko)
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KR101746774B1 (en
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강승범
곽민환
손남기
김기출
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목원대학교 산학협력단
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    • 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
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0294—Multi-channel spectroscopy
    • 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
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
    • G01J3/0218—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using optical fibers
    • 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
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2823—Imaging spectrometer

Abstract

The present invention relates to a pulse laser for generating optical pulses; A first allocating unit for allocating the generated optical pulses corresponding to the plurality of channels; A plurality of transmission units for generating terahertz waves using the assigned optical pulses and for radiating the generated terahertz waves to a sample region corresponding to the corresponding channels and a spectroscopic characteristic detecting unit for detecting spectral characteristics of the respective sample regions irradiated with the terahertz wave Channel spectral system using a multi-channel terahertz wave including a plurality of reception units for receiving a multi-channel terahertz wave.

Description

[0001] MULTI-CHANNEL TERAHERTZ TIME DOMAIN SPECTROSCOPY SYSTEM [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-domain spectroscopy system using multi-channel THz waves, and more particularly, to a technique for detecting and analyzing spectral characteristics of a plurality of sample regions corresponding to multiple channels, .

Terahertz waves are used to analyze the electro-optical spectroscopic properties of various materials, as they have the properties of being transmitted or reflected in samples such as insulators, dielectrics, plastics and various materials.

Patent Document 1 is directed to a time domain spectroscope using a terahertz electromagnetic wave, and is a technique for detecting spectral characteristics reflected from a sample to be measured for terahertz electromagnetic waves. Patent Document 2 relates to a terahertz spectral imaging apparatus, And is a technique for detecting spectral characteristics transmitted through a sample to be measured with a Hertz electromagnetic wave.

However, although Patent Document 1 or 2 detects the spectral characteristics reflected or transmitted by the sample, the spectral characteristics reflected and transmitted by the sample are not mutually converted and detected, and the detection accuracy may be low.

Patent Document 1 does not disclose a technology for detecting spectral characteristics of each of a plurality of sample regions. Patent Document 2 discloses a technique for detecting a plurality of spectral characteristics. However, The time required for scanning the sample is prolonged and there is a problem that the large area material or the plurality of materials divided into a plurality of sample areas can not be simultaneously analyzed.

1. Korean Patent No. 10-1017796 (Feb. 18, 2011) 2. Korean Patent No. 10-0815615 (Mar. 14, 2008)

The present invention provides a time domain spectroscopy system using multichannel THz waves that improve the detection accuracy by detecting and converting the spectral characteristics of the reflected THz waves and the spectral characteristics of the transmitted THz waves in each sample area .

In the present invention, a large-area material or a plurality of materials divided into a plurality of sample regions are simultaneously analyzed and implemented as a two-dimensional image, thereby improving detection versatility of various material types, reducing analysis time, Channel spectral system using a terahertz wave.

The present invention provides a time domain spectroscopy system using multichannel THz waves that minimizes the problem of optical alignment by constructing the entire optical path with optical fibers.

A time-domain spectroscopy system using multi-channel THz waves for detecting spectral characteristics of a plurality of sample regions corresponding to multiple channels of the present invention includes: a pulse laser generating an optical pulse; A first allocating unit for allocating the generated optical pulses corresponding to the plurality of channels; A plurality of transmission units for generating terahertz waves using the assigned optical pulses and for radiating the generated terahertz waves to a sample region corresponding to the corresponding channels and a spectroscopic characteristic detecting unit for detecting spectral characteristics of the respective sample regions irradiated with the terahertz wave And a plurality of receiving units.

The pulse laser and a plurality of transmitting and receiving units may be connected to an optical fiber line.

The first allocator may allocate the optical pulses to a plurality of transmission units corresponding to a plurality of channels using an optical splitter or an optical switch.

The plurality of transmitters may generate a terahertz wave by accelerating free electrons generated by optical absorption of an optical pulse in a state where a modulation voltage is applied.

The time domain spectroscopy system using multi-channel THz waves may further include a delay line for delaying the THz waves detected by the plurality of receivers.

The plurality of receiving units can detect and convert the spectral characteristics of the terahertz wave transmitted through each sample region and the spectral characteristics of the reflected terahertz wave.

The time domain spectroscopy system using multi-channel THz waves may further include an analyzer for capturing the detected spectroscopic characteristics and analyzing a plurality of sample regions by compensating the phases of the captured spectroscopic characteristics.

The analysis unit may simultaneously analyze a large-area material divided into the plurality of sample regions by region, and may simultaneously analyze a plurality of materials classified into the plurality of sample regions.

The analysis unit may analyze the spectral characteristics detected at respective positions of the plurality of sample regions and implement the image as a two-dimensional image.

The present invention can improve the detection accuracy by converting the spectral characteristics of the reflected multi-channel THz waves and the spectral characteristics of the transmitted multi-channel THz waves through the plurality of reception units.

The present invention can simultaneously analyze a large area material or a plurality of materials divided into a plurality of sample areas and realize them as two-dimensional images, thereby improving the versatility of detection of various material types, reducing the analysis time, .

The present invention can minimize the problem of optical alignment by configuring the entire optical path with an optical fiber.

FIG. 1 illustrates a time domain spectroscopy system using multi-channel THz waves according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and accompanying drawings, but the present invention is not limited to or limited by the embodiments.

FIG. 1 illustrates a time-domain spectroscopy system using multi-channel THz waves according to an embodiment of the present invention. Referring to FIG. 1, a time-domain spectroscopic system using multi-channel THz waves detecting spectral characteristics of a plurality of sample regions corresponding to multi- The spectroscopic system 100 includes a pulse laser 110, a first allocation unit 121, a second allocation unit 122, a plurality of transmission units 130, a plurality of reception units 150, and an analysis unit 160 .

The pulse laser 110 generates a light pulse and transmits the generated light pulse to the first allocating unit 121 and the second allocating unit 122.

The time domain spectroscopic system 100 is connected to the pulsed laser 110 and the first and second assigning units 121 and 122 through an optical line.

The optical fiber is an optical fiber fabricated such that a glass having a high refractive index is formed in the center portion and a glass having a low refractive index is formed in the outer portion and the light passing through the center glass is totally reflected.

The optical fiber has a very low energy loss for the optical pulse and is free from interference or crosstalk against external electromagnetic waves, so that it is robust against changes in the external environment and can minimize the problem of optical alignment.

The optical fiber is divided into a stepped optical fiber and a hill-shaped optical fiber according to the refractive index distribution of the core. In the present invention, the optical fiber can use a single mode optical fiber, but is not limited thereto.

The time domain spectroscopy system 100 further includes a variable optical coupler (not shown) for branching and transmitting the optical pulses generated from the pulse laser 110 to the first allocator 121 and the second allocator 122 .

The optical coupler may be used as an optical fiber element and may be a fiber coupler having various fixed branching ratios such as 50:50, 10:90 and 1:99, and may be a variable coupler capable of externally adjusting the branching ratio.

The power of the optical pulse is changed in accordance with the structure and the characteristic of the device and the optimum point of the optical pulse power should be set based on the device characteristic. If the optical pulse power is incident at an excessive optical pulse power, The optical coupler can branch to the optical pulse power of the set optimal point.

An optical fiber delay line may be formed in the optical fiber line between the pulse laser 110 and the first allocating unit 121. [

The first allocator 121 allocates the generated optical pulses corresponding to the plurality of channels, and the plurality of transmitters 130 generates terahertz waves using the optical pulses allocated thereto.

The time domain spectroscopic system 100 transmits all the optical pulses in the optical fiber line as the transmission path of optical pulses is connected between the first allocator 121 and the plurality of transmitters 130, Can be minimized.

The first allocating unit 121 may allocate optical pulses to a plurality of transmitting units 130 corresponding to a plurality of channels using a light splitter or an optical switch and the second allocating unit 122 may allocate optical pulses The optical pulses can be allocated to the plurality of reception units 150 corresponding to the multiple channels.

Conventional time domain spectroscopic systems use ultrarapid optical pulses through a single channel and have a problem that the power of the ultrarapid optical pulses is so high that the total power can not be fully utilized. However, the time using the multi-channel terahertz wave of the present invention The area spectroscopy system 100 can efficiently use the entire power by using a light splitter or an optical switch.

The optical pulse may have a central wavelength of 1700 nm or less and a pulse width of 120 fs (fs) or less, preferably a central wavelength of 1550 nm and a pulse width of 100 fs.

The optical fiber has the minimum transmission loss in the band of 1550nm optical communication wavelength, and the optical pulse with the bandwidth of 1550nm and the pulse width of 100fs can be used as the ultrarapid optical pulse laser.

The plurality of transmitting units 130 or the plurality of receiving units 150 have a band of 1550 nm at an absorption level and excite the conduction electrons through the absorption of light to generate a terahertz wave or a terahertz wave.

A pulse width of 100 fs or less may be a pulse width suitable for generating or detecting a terahertz wave having a pulse width of 1 ps or less, and may be a pulse width considering physical characteristics such as a carrier lifetime of a device material.

The plurality of transmitting units 130 can generate terahertz waves by accelerating the free electrons generated by the optical absorption of the optical pulses allocated in the state where the modulation voltage is applied.

The terahertz wave is an electromagnetic wave having a wavelength in the range of GHz to THz, and has a longer wavelength than visible light or infrared light. However, it has a strong penetrating power such as an X-ray and has lower energy than X-ray.

The plurality of transmitters 130 may generate a terahertz wave using a photoconductive antenna or a small dipole antenna. For example, a plurality of transmitting units 130 can use a material such as LT-InGaAs / InAlAs on an InP substrate, and a LT (Low Temperature) -GaAs photoconductive material having a low temperature grown can be used as a material Lt; / RTI >

When a light pulse is excited in a state in which a modulating voltage is applied to a small dipole antenna, a plurality of transmitting units 130 generate free carriers such as electrons and holes due to light absorption, so that a current flows momentarily and a terahertz wave Lt; / RTI > The range of the terahertz wave may range from 0.1 THz to 4 THz.

The time domain spectroscopic system 100 may further include a modulation voltage generator 170 for providing a plurality of transmission units 130 or the analysis unit 160 with a voltage modulation.

The modulation voltage generating unit 170 may provide a modulation voltage for generating a terahertz wave to the plurality of transmitting units 130 and may generate a lock-in amp reference signal to the plurality of receiving units 150 Lt; / RTI >

The analysis unit 160 may utilize a lock-in amp to compensate for the output signal detected by the plurality of receiving units 150, and may use a phase sensitive measurement method. The modulation frequency of the provided modulation voltage may be referred to as a reference signal .

The plurality of transmitting units 130 radiate the generated terahertz wave into a sample region corresponding to the corresponding channel.

The sample divided into the plurality of sample regions may be one large-area material, may be a plurality of materials, and may be fixed by the sample holder 140.

The sample can be used for various purposes such as detection of explosive substances such as TNT or RDX, detection of pesticides or other harmful chemicals, defect inspection of electronic components, drug research and doping inspection of semiconductor materials, have.

The plurality of reception units 150 detect the spectral characteristics of each sample region in which the terahertz wave is radiated.

The plurality of reception units 150 can detect and convert the spectral characteristics of the terahertz wave transmitted through each sample region and the spectral characteristics of the reflected terahertz wave.

As shown in FIG. 1, the plurality of receiving units 150 may detect the spectral characteristics of the THz waves transmitted through the respective sample regions, or may be positioned at a certain angle with respect to one surface of each sample region, The spectral characteristic of the terahertz wave can be detected.

Since the plurality of receiving sections 150 can detect and convert the spectral characteristics of the transmitted and reflected THz waves into the respective sample regions, the accuracy of detection can be improved.

The plurality of transmitting units 130 and the plurality of receiving units 150 are array structures arranged in accordance with a rule, and each sample region is set in an area corresponding to the array structure.

The analyzer 160 captures the detected spectroscopic characteristics and analyzes a plurality of sample regions by compensating the phases of the captured spectroscopic characteristics.

The analysis unit 160 may analyze a plurality of sample regions after removing noise from each captured spectral characteristic.

The analysis unit 160 can simultaneously analyze a large-area material divided into a plurality of sample regions by region, analyze a plurality of materials classified into a plurality of sample regions at the same time, Since the detected spectroscopic characteristics can be analyzed and implemented as a two-dimensional image, the versatility of detection of various types of materials can be enhanced, analysis time can be shortened, and the image can be utilized as an image device.

The time domain spectroscopy system 100 may further include a delay line for delaying each of the terahertz waves detected by the plurality of reception units 150. [

The analyzer 160 may analyze the spectral characteristic of each of the terahertz waves detected by the delay line and the lock-in amp or a timing or synchronous detection method of sampling the terahertz wave.

The total scan time or scan rate of the delay line may be between a few seconds and several minutes, and various times may be applied depending on the measurement conditions, and the shorter the total scan time of the delay line, the shorter the measurement time.

The analysis unit 160 is connected between the analysis unit 160 and the plurality of reception units 150 through an electrical line and the analysis unit 160 analyzes the signals of the respective terahertz waves detected from the plurality of reception units 150 It is possible to receive spectroscopic characteristics.

The analysis unit 160 can measure the current generated by applying the electric field of the transmitted or reflected terahertz pulse to the device using a lock-in amp, and when the delay line moves to each of the plurality of receiving units 150 The terahertz pulse waveform can be measured by measuring the output current such as the electric field strength of the terahertz pulse, and the optical sampling method can be applied.

The analysis unit 160 measures the terahertz pulse shape transmitted or reflected on the sample to be measured in the time domain and performs Fourier transform to generate intensity and phase information in each frequency domain. Based on the generated information, The complex refractive index, the complex permittivity, and the complex conductivity are calculated.

The analysis unit 160 measures a terahertz pulse using an optical sampling method and a phase sensitivity measurement method, measures a reference pulse which is not transmitted or reflected in each sample region, extracts each physical quantity in a Fourier- The physical property of each sample region can be measured by calculating the difference between the physical quantity for the terahertz pulse and the physical quantity for the reference pulse.

The modulation voltage generating unit 170 is connected between the modulation voltage generating unit 170 and the plurality of transmitting units 130 and between the modulation voltage generating unit 170 and the analyzing unit 160 through an electric line, And may provide a modulation voltage to the plurality of transmission units 130 and the analysis unit 160. [

The time domain spectroscopy system 100 can be implemented as a two-dimensional terahertz imaging apparatus by downsizing a plurality of transmitting units 130 and a plurality of receiving units 150. [

100: Time domain spectroscopy system
110: pulse laser 121: first allocation unit
122: second allocation unit 130:
140: sample holder 150: plural receivers
160: Analyzing unit 170: Modulation voltage generating unit

Claims (10)

A time-domain spectroscopy system using multi-channel THz waves for detecting spectral characteristics of a plurality of sample regions corresponding to multiple channels,
A pulse laser generating an optical pulse;
A first allocating unit for allocating the generated optical pulses corresponding to the plurality of channels;
A plurality of transmitters for generating terahertz waves using the assigned optical pulses and emitting the generated terahertz waves to a sample area corresponding to the corresponding channels,
And a plurality of receivers for detecting spectral characteristics of each sample region from which the terahertz wave is radiated. The method according to claim 1,
The time domain spectroscopy system using the multi-channel THz waves, wherein the pulse laser and the plurality of transmitting and receiving units are connected by optical fiber lines. The method according to claim 1,
Wherein the first allocation unit allocates the optical pulses to a plurality of transmission units corresponding to the plurality of channels using an optical splitter or an optical switch. The method according to claim 1,
Wherein the plurality of transmitters accelerate free electrons generated by light absorption of optical pulses in a state where a modulation voltage is applied to generate a terahertz wave. The method according to claim 1,
And a delay line for delaying the terahertz wave detected by the plurality of reception units. The method according to claim 1,
Wherein the plurality of receiving units convert a spectral characteristic of a terahertz wave transmitted through each sample region and a spectral characteristic of a reflected terahertz wave to detect each of the plurality of receiving regions. The method according to claim 1,
Further comprising an analyzer for capturing the detected spectroscopic characteristics and analyzing a plurality of sample regions by compensating a phase for each captured spectroscopic characteristic. 8. The method of claim 7,
Wherein the analysis unit simultaneously analyzes a large-area material divided into the plurality of sample regions by region, and uses the multi-channel terahertz wave. 8. The method of claim 7,
Wherein the analysis unit simultaneously analyzes a plurality of materials classified into the plurality of sample regions. 8. The method of claim 7,
Wherein the analyzer analyzes the spectral characteristics detected at respective positions of the plurality of sample regions and implements the spectral characteristics as a two-dimensional image using the multi-channel terahertz wave.
KR1020150168784A 2015-11-30 2015-11-30 Multi-channel terahertz time domain spectroscopy system KR101746774B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110160573A (en) * 2019-07-08 2019-08-23 山东省科学院激光研究所 Ai Hezi ultrafast modulation pulse scan laser and distributed optical fiber sensing system

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KR102140720B1 (en) 2018-12-19 2020-08-03 재단법인 한국탄소융합기술원 Imaging system for evaluating dispersion degree of carbon polymer composites

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110160573A (en) * 2019-07-08 2019-08-23 山东省科学院激光研究所 Ai Hezi ultrafast modulation pulse scan laser and distributed optical fiber sensing system
CN110160573B (en) * 2019-07-08 2022-03-25 山东省科学院激光研究所 Escholtz ultrafast modulation pulse scanning laser and distributed optical fiber sensing system

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