CN104515602A - Terahertz pulse detector based on electro-optic sampling principle - Google Patents
Terahertz pulse detector based on electro-optic sampling principle Download PDFInfo
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- CN104515602A CN104515602A CN201410758974.6A CN201410758974A CN104515602A CN 104515602 A CN104515602 A CN 104515602A CN 201410758974 A CN201410758974 A CN 201410758974A CN 104515602 A CN104515602 A CN 104515602A
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Abstract
The invention provides a terahertz pulse detector based on an electro-optic sampling principle. The terahertz pulse detector comprises an electro-optic crystal, a lambda/4 wave plate, a polarization beam splitter and a differential detector, and the differential detector comprises an avalanche diode and a matching resistor which are connected. The avalanche diode and the matching resistor are arranged in the differential detector and connected, so that signal-to-noise ratio and dynamic range of terahertz signals are increased greatly.
Description
Technical field
The present invention relates to acquisition of signal technical field, refer to a kind of terahertz pulse detector based on electro-optic sampling principle especially.
Background technology
Terahertz detection is a gordian technique of Terahertz Technology development, is the key link that Terahertz Technology puts into practical application.The power in current terahertz emission source is general all lower, therefore develop high sensitivity, high s/n ratio terahertz detection technology particularly important.The detection method of Terahertz is many, and the form according to terahertz emission is different, they can be roughly divided into the detection of terahertz pulse radiation and detection two class of THz continuous wave signal.Wherein for the detection of terahertz pulse, electro-optic sampling is relevant terahertz pulse detection method most widely used at present.It is lower that existing terahertz detection adopts traditional silicon photo diode laser energy to be changed into the conversion efficiency of electric signal, terahertz signal signal to noise ratio (S/N ratio) taught low, and this will the detectivity of impact to Terahertz.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of terahertz pulse detector based on electro-optic sampling principle, to solve the low problem of terahertz signal signal to noise ratio (S/N ratio).
For solving the problems of the technologies described above, embodiments of the invention provide a kind of terahertz pulse detector based on electro-optic sampling principle, the described terahertz pulse detector based on electro-optic sampling principle comprises: electro-optic crystal, λ/4 wave plate, polarizing beam splitter mirror and differential detector, described differential detector comprises avalanche diode and join resistance, described avalanche diode with described join to hinder be connected.
Preferably, described avalanche diode applies reverse biased.
Preferably, the voltage of described applying reverse biased is 10V to 60V.
Preferably, the voltage of described applying reverse biased is 20V.
Preferably, the voltage of described applying reverse biased is 30V.
Preferably, the resistance of described avalanche diode be described in join resistance 2 to 400 times of resistance.
Preferably, described avalanche diode resistance for described in join resistance 200 times of resistance.
Preferably, described avalanche diode is connected with galvo-preamplifier.
Preferably, described differential detector comprises two avalanche diodes, described avalanche diode with join hinder in parallel.
The beneficial effect of technique scheme of the present invention is as follows:
In such scheme, by arranging avalanche diode and join resistance in differential detector, and by described avalanche diode with described join to hinder be connected, greatly promote signal to noise ratio (S/N ratio) and the dynamic range of terahertz signal.
Accompanying drawing explanation
Fig. 1 is the terahertz pulse panel detector structure figure based on electro-optic sampling principle of the present invention;
Fig. 2 is the avalanche diode applied voltage test circuit diagram of the terahertz pulse detector based on electro-optic sampling principle of the present invention;
Fig. 3 is the avalanche diode biasing Analysis signal-to-noise ratio (SNR) of the terahertz pulse detector based on electro-optic sampling principle of the present invention;
Fig. 4 hinders test circuit schematic diagram and pictorial diagram joining of the terahertz pulse detector based on electro-optic sampling principle of the present invention;
The diode of Fig. 5 terahertz pulse detector based on electro-optic sampling principle of the present invention meets different resistance Analysis signal-to-noise ratio (SNR) figure;
The detection performance that the diode of Fig. 6 terahertz pulse detector based on electro-optic sampling principle of the present invention connects prime amplifier compares schematic diagram;
Fig. 7 is that terahertz detector of the present invention (S2384) compares schematic diagram with the signal to noise ratio (S/N ratio) of auto-balanced detection device (ABL).
Embodiment
For making the technical problem to be solved in the present invention, technical scheme and advantage clearly, be described in detail below in conjunction with the accompanying drawings and the specific embodiments.
Electro-optic sampling method detects terahertz pulse, utilize the electro-optic crystal that laser beam and terahertz pulse conllinear are <110> through high preferred orientation, terahertz pulse is irradiated on electro-optic crystal, the index ellipsoid of electro-optic crystal will be changed by it, this change will cause the polarization state of exploring laser light to become elliptic polarization from linear polarization, again through polarizing beam splitter mirror (conventional is wollaston prism), be divided into s polarization and p polarization two bundle, the light intensity difference of this two-beam is then proportional to Terahertz electric field.Use differential detector the light intensity difference of this two-beam can be converted to difference between current, thus detect the electric field information of terahertz electromagnetic radiation pulse.
As shown in Figure 1, a kind of terahertz pulse detector based on electro-optic sampling principle of embodiments of the invention, the described terahertz pulse detector based on electro-optic sampling principle comprises: electro-optic crystal 1, λ/4 wave plate, polarizing beam splitter mirror 2 and differential detector 3, λ/4 wave plate is between electro-optic crystal 1 and polarizing beam splitter mirror 2, described differential detector comprises avalanche diode 4 and joins resistance 5, and described avalanche diode 4 is joined resistance 5 be connected with described.
Preferably, described avalanche diode 4 applies reverse biased.
Preferably, the voltage of described applying reverse biased is 10V to 60V.
Preferably, the voltage of described applying reverse biased is 20V.
Preferably, the voltage of described applying reverse biased is 30V.
Wherein, avalanche diode, from having enlarge-effect in time adding reverse biased, utilizes this enlarge-effect, terahertz signal can be amplified.Experiment selects avalanche diode to test, and its test circuit as shown in Figure 2; By two avalanche diode series aiding connections, and add reverse biased.In order to study avalanche diode detection performance, by changing bias voltage, observe the terahertz signal detected.As shown in Figure 3, when institute's biasing is 20V, the signal value now recorded is maximum., consider together in conjunction with noise, when finding that institute's biasing is 30V, now signal to noise ratio (S/N ratio) is optimum, about 900:1 meanwhile.
Preferably, the resistance of described avalanche diode 4 be described in join 2 to 400 times of resistance 5 resistance.
Preferably, described avalanche diode 4 resistance for described in join 200 times of resistance 5 resistance.
Wherein, study diode and join the impact of resistance on detectable signal.PIN photodiode is tested, and as shown in Figure 4, by the photodiode reverse parallel connection of two same model, when there being light to be radiated on two diodes, it is equivalent to two current sources to circuit, and two diode reverse parallel connections can be played difference effect; Simultaneously, join resistance for one in parallel, make current conversion be voltage signal and realize amplifying, utilize lock-in amplifier measurement to join resistance both end voltage value, change difference simultaneously and join resistance resistance (5k Ω, 10k Ω, 30k Ω, 1M Ω resistance), observe that diode institute is in parallel joins the impact hindered signal.After mixing up balance, from resistance two ends extension line, receive lock-in amplifier A (voltage mode) port, scanned by one dimension motorized precision translation stage, error of measurement component voltage value, test result as shown in Figure 5.The equivalent resistance of PIN diode self is 2M Ω, and when joining, resistance resistance is larger, more obvious to the amplification effect of terahertz signal, but enlargement factor is disproportionate with join resistance; Noise also amplifies thereupon simultaneously.By observing, join resistance resistance and diode self resistance when being close, signal noise amplification ratio is more remarkable; When joining resistance much smaller than diode self resistance, noise amplifies not obvious, and noise intensity is close, and the terahertz signal signal to noise ratio (S/N ratio) of joining the larger PIN diode measurement of resistance is in such cases higher.Analytical test result is known, and when system joins resistance for 10k Ω, system signal noise ratio is optimum.
Preferably, described avalanche diode is connected with galvo-preamplifier.
Wherein, join resistance situation for avalanche diode 1M Ω in parallel, it connects the effect of prime amplifier as shown in Figure 6.Be not difficult to find, be adjusted to suitable sensitivity gear (10
-5) time, detectable signal has remarkable amplification, and enlargement factor and sensitivity are inversely proportional to, and namely select 10
-5the magnitude of voltage that sensitivity records is about 10
-410 times of sensitivity.Connect the intensity that prime amplifier significantly can change measured signal, and then improve detection system signal to noise ratio (S/N ratio).
Relatively based on the terahertz pulse detector of technique scheme and the signal to noise ratio (S/N ratio) of market product auto-balanced detection device, as shown in Figure 7, after normalized is done to signal intensity, the signal intensity of two kinds of detectors is consistent, and the noise bounce of auto-balanced detection device is obvious, terahertz pulse detector relative smooth of the present invention is a lot, and signal to noise ratio (S/N ratio) is better than the like product from foreign procurement.
Terahertz pulse detector based on electro-optic sampling principle of the present invention, by arranging avalanche diode and join resistance in differential detector, and by described avalanche diode with described join to hinder be connected, greatly promote signal to noise ratio (S/N ratio) and the dynamic range of terahertz signal.
The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from principle of the present invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (9)
1. the terahertz pulse detector based on electro-optic sampling principle, the described terahertz pulse detector based on electro-optic sampling principle comprises: electro-optic crystal, λ/4 wave plate, polarizing beam splitter mirror and differential detector, it is characterized in that, described differential detector comprises avalanche diode and join resistance, described avalanche diode with described join to hinder be connected.
2. the terahertz pulse detector based on electro-optic sampling principle according to claim 1, is characterized in that, described avalanche diode applies reverse biased.
3. the terahertz pulse detector based on electro-optic sampling principle according to claim 2, is characterized in that, the voltage of described applying reverse biased is 10V to 60V.
4. the terahertz pulse detector based on electro-optic sampling principle according to claim 3, is characterized in that, the voltage of described applying reverse biased is 20V.
5. the terahertz pulse detector based on electro-optic sampling principle according to claim 3, is characterized in that, the voltage of described applying reverse biased is 30V.
6. the terahertz pulse detector based on electro-optic sampling principle according to claim 1, is characterized in that, the resistance of described avalanche diode be described in join 2 to 400 times of resistance resistance.
7. the terahertz pulse detector based on electro-optic sampling principle according to claim 6, is characterized in that, the resistance of described avalanche diode for described in join 200 times of resistance resistance.
8. the terahertz pulse detector based on electro-optic sampling principle according to claim 1, it is characterized in that, described avalanche diode is connected with galvo-preamplifier.
9. according to the terahertz pulse detector based on electro-optic sampling principle one of claim 1 to 8 Suo Shu, it is characterized in that, described differential detector comprises two avalanche diodes, described avalanche diode with join hinder in parallel.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108106723A (en) * | 2017-12-18 | 2018-06-01 | 北京无线电计量测试研究所 | A kind of device and method for enhancing Terahertz Electro-optic sampling detectivity |
| RU2777461C1 (en) * | 2021-09-29 | 2022-08-04 | Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский Нижегородский государственный университет им. Н.И. Лобачевского" | Working node of the pulsed terahertz radiation detector |
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| CN101701852A (en) * | 2009-09-18 | 2010-05-05 | 深圳大学 | Electro-optic sampling device used for measuring terahertz optical pulse and measuring method thereof |
| CN102914366A (en) * | 2012-10-12 | 2013-02-06 | 中山大学 | Photoelectric differential detector with high common-mode rejection ratio (CMRR) |
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Patent Citations (2)
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| CN101701852A (en) * | 2009-09-18 | 2010-05-05 | 深圳大学 | Electro-optic sampling device used for measuring terahertz optical pulse and measuring method thereof |
| CN102914366A (en) * | 2012-10-12 | 2013-02-06 | 中山大学 | Photoelectric differential detector with high common-mode rejection ratio (CMRR) |
Non-Patent Citations (2)
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| G.ZHAO ET AL.: "Design and performance of a THz emission and detection setup based on a semi-insulating GaAs emitter", 《REVIEW OF SCIENTIFIC INSTRUMENTS》 * |
| 陈龙超等: "高灵敏度低噪声太赫兹电光探测器研究", 《电子学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108106723A (en) * | 2017-12-18 | 2018-06-01 | 北京无线电计量测试研究所 | A kind of device and method for enhancing Terahertz Electro-optic sampling detectivity |
| CN108106723B (en) * | 2017-12-18 | 2020-09-18 | 北京无线电计量测试研究所 | Device and method for enhancing detection sensitivity of terahertz electro-optic sampling technology |
| RU2777461C1 (en) * | 2021-09-29 | 2022-08-04 | Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский Нижегородский государственный университет им. Н.И. Лобачевского" | Working node of the pulsed terahertz radiation detector |
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