Terahertz single-photon detection system

Abstract

The utility model discloses a terahertz single-photon detection system, which comprises a terahertz single-photon detector, a current-voltage converter, a comparator, an integration module and a processing module, terahertz single-photon signals enter the terahertz single-photon detector through an optical channel, the output end of the terahertz single-photon detector is connected with the input end of the current-voltage converter, the output end of the current-voltage converter is connected with the input end of the comparator, and the output end of the comparator is connected with the input end of the integration module. The output end of the integration module is connected with the input end of the processing module. The utility model discloses a terahertz single-photon detection system, which is characterized in that current generated by a terahertz single-photon detector is converted into voltage through a current-voltage converter, and then dark counting signals lower than a threshold value in the voltage are prevented from passing through a comparator; and finally, the number of terahertz single photons is obtained through the integration module and the processing module in sequence, so that the influence of dark counting on a detection result is effectively reduced.

Description

Technical Field

[0001] The utility model relates to the field of single-photon detection equipment, in particular to a terahertz single-photon detection system. Background Art

[0002] Terahertz (THz) refers to a wide spectrum of electromagnetic waves ranging from 100GHZ to 10THZ, with wavelengths of 3mm to 30um, between millimeter waves and infrared light waves. At present, the international community has reached a consensus on THz radiation, that is, THz is a new radiation source with many unique advantages; THz technology is a very important cross-cutting frontier field, providing a very attractive opportunity for technological innovation, national economic development and national security.

[0003] On the one hand, since the terahertz spectrum of a substance (including transmission spectrum and reflection spectrum) contains very rich physical and chemical information, studying the spectrum of a substance in this band is of great significance for exploring the structure of the substance. On the other hand, compared with traditional light sources, terahertz pulse light sources have many unique properties. The reason why people pay attention to THz technology is that THz rays are ubiquitous and are an effective clue and tool for people to understand nature. Compared with electromagnetic waves in other bands, such as infrared and microwaves, people's understanding and application of terahertz waves are still very scarce.

[0004] The unique properties of terahertz have brought far-reaching impacts to the fields of communications (broadband communications), radar, electronic countermeasures, electromagnetic weapons, astronomy, medical imaging (label-free genetic testing, imaging at the cellular level), non-destructive testing, and safety inspections (inspection of biochemical substances). Since the frequency of terahertz is very high, its spatial resolution is also very high; and since its pulse is very short (picosecond level), it has a very high temporal resolution. Terahertz imaging technology and terahertz spectroscopy technology thus constitute the two main key technologies for terahertz applications. At the same time, since the energy of terahertz is very small and will not cause damage to matter, it has more advantages than X-rays.

[0005] However, there are currently the following defects in detecting photons in the terahertz frequency band:

[0006] 1. Detection using the nonlinear effect of electro-optical crystals. Although this method has high detection sensitivity, it can only work under irradiation of the corresponding terahertz frequency and is large in size and difficult to integrate.

[0007] 2. Although the detection speed and efficiency of photon detectors are fast, the dark current and dark counts are large, making it difficult to detect relatively weak terahertz radiation.

[0008] Therefore, it is necessary to improve the existing technology and propose a single-photon detection system that can better detect in the terahertz frequency band. Utility Model Content

[0009] In order to solve the problem of large dark counts when detecting photons in the terahertz frequency band, the utility model proposes a terahertz single photon detection system.

[0010] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0011] A terahertz single-photon detection system comprises a terahertz single-photon detector, a current-to-voltage converter, a comparator, an integration module and a processing module;

[0012] The terahertz single-photon signal enters the terahertz single-photon detector through the optical channel, the output end of the terahertz single-photon detector is connected to the input end of the current-voltage converter, the output end of the current-voltage converter is connected to the input end of the comparator, the output end of the comparator is connected to the input end of the integration module, and the output end of the integration module is connected to the input end of the processing module.

[0013] In the above scheme, the current generated by the terahertz single-photon detector due to the detection of terahertz single photons is first converted into voltage through a current-to-voltage converter, and then a comparator is used to prevent the dark count signal below the threshold in the voltage from passing through. Finally, the number of terahertz single photons is obtained through an integration module and a processing module in sequence, thereby effectively reducing the influence of dark counts on the detection results.

[0014] Preferably, the terahertz single-photon detector includes a semiconductor heterojunction, a two-dimensional electron gas formed on the surface of the semiconductor heterojunction, a detection electrode formed on the surface of the semiconductor heterojunction, a first quantum dot and a single electron measuring instrument formed on the surface of the semiconductor heterojunction; the first quantum dot is formed between the detection electrode and the single electron measuring instrument.

[0015] Preferably, the single electron measuring instrument is capacitively coupled to the first quantum dot.

[0016] Preferably, the distance between the two-dimensional electron gas and the semiconductor heterojunction is 1 nm-100 nm.

[0017] Preferably, the electron density in the two-dimensional electron gas is 1×10 11 cm -2 .

[0018] Preferably, the single electron measuring instrument comprises a gate electrode, a second quantum dot, a first electrode and a second electrode formed on the surface of a semiconductor heterojunction;

[0019] The first quantum dot is formed between the end of the detection electrode and the end of the gate electrode, and the second quantum dot is formed between the end of the gate electrode, the end of the first electrode and the end of the second electrode.

[0020] Preferably, the first quantum dot and the second quantum dot are capacitively coupled.

[0021] Preferably, the integration module includes a resistor R1, an operational amplifier and a capacitor C1;

[0022] The output end of the comparator is connected to one end of the resistor R1, the other end of the resistor R1 and one end of the capacitor C1 are respectively connected to the inverting input end of the operational amplifier, the same-direction input end of the operational amplifier is grounded, and the other end of the capacitor C1 and the input end of the processing module are respectively connected to the output end of the operational amplifier.

[0023] Preferably, it further comprises a digital-to-analog conversion module; the output end of the processing module is connected to the input end of the terahertz single-photon detector through the digital-to-analog conversion module.

[0024] Preferably, the processing module is FPGA.

[0025] Beneficial technical effects of the utility model:

[0026] The utility model provides a terahertz single-photon detection system, which first converts the current generated by the terahertz single-photon detector due to the detection of terahertz single photons into a voltage through a current-to-voltage converter, then blocks the dark count signal below the threshold in the voltage from passing through a comparator, and finally obtains the number of terahertz single photons through an integration module and a processing module in sequence, thereby effectively reducing the influence of dark counts on the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the overall module connection of the utility model;

[0028] Figure 2 This is a schematic diagram of the overall structure of the terahertz single-photon detector in the utility model;

[0029] Figure 3 This is a circuit schematic diagram of the integration module in the utility model;

[0030] Among them: 001, terahertz single-photon detector; 002, current-voltage converter; 003, comparator; 004, integration module; 005, processing module; 006, digital-to-analog conversion module; 1, detection electrode; 2, first quantum dot; 3, gate electrode; 4, second quantum dot; 5, first electrode; 6, second electrode. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the utility model more clearly understood, the utility model is further described in detail below in conjunction with embodiments, but the scope of protection claimed in the utility model is not limited to the following specific embodiments.

[0032] Example 1

[0033] like Figure 1 As shown, a terahertz single photon detection system includes a terahertz single photon detector 001, a current-to-voltage converter 002, a comparator 003, an integration module 004 and a processing module 005;

[0034] The terahertz single-photon signal enters the terahertz single-photon detector 001 through the optical channel, the output end of the terahertz single-photon detector 001 is connected to the input end of the current-voltage converter 002, the output end of the current-voltage converter 002 is connected to the input end of the comparator 003, the output end of the comparator 003 is connected to the input end of the integration module 004, and the output end of the integration module 004 is connected to the input end of the processing module 005.

[0035] In the specific implementation process, the current generated by the terahertz single-photon detector 001 due to the detection of terahertz single photons is first converted into voltage through the current-to-voltage converter 002, and then the dark count signal below the threshold in the voltage is blocked from passing through the comparator 003. Finally, the number of terahertz single photons is obtained through the integration module 004 and the processing module 005 in sequence, which effectively reduces the influence of dark counts on the detection results.

[0036] More specifically, Figure 2 As shown, the terahertz single-photon detector 001 includes a semiconductor heterojunction, a two-dimensional electron gas formed on the surface of the semiconductor heterojunction, a detection electrode 1 formed on the surface of the semiconductor heterojunction, a first quantum dot 2 and a single electron measuring instrument formed on the surface of the semiconductor heterojunction; the first quantum dot 2 is formed between the detection electrode 1 and the single electron measuring instrument.

[0037] More specifically, the single electron measuring instrument is capacitively coupled to the first quantum dot 2 .

[0038] In the specific implementation process, the terahertz single-photon signal enters the terahertz single-photon detector 001 through the optical channel, and the terahertz single photons are collected by the detection electrode 1. When the terahertz single photon is collected, an electron in the first quantum dot 2 is excited by plasma to fly to the surrounding electron reservoir, so that it carries a hole with a unit charge of e. Since the electrons in the electron reservoir and the holes in the first quantum dot 2 are separated by a potential barrier, the holes have a long recombination life τ. Because the single-electron meter capacitively coupled to the first quantum dot 2 is very sensitive to the surrounding electrostatic environment, a hole in the first quantum dot 2 will cause the current in the single-electron meter to change ΔI, so each time the first quantum dot 2 absorbs a photon, an average of τΔI / e electrons will be generated to pass through the single-electron meter, causing the current in the single-electron meter to jump, thereby having a high sensitivity to the detection of terahertz single photons.

[0039] More specifically, the distance between the two-dimensional electron gas and the semiconductor heterojunction is 1 nm-100 nm.

[0040] More specifically, the electron density in the two-dimensional electron gas is 1×10 11 cm -2 , electron mobility 5×10 5 cm 2 V - 1 S -1 .

[0041] More specifically, the single electron measuring instrument comprises a gate electrode 3, a second quantum dot 4, a first electrode 5 and a second electrode 6 formed on the surface of a semiconductor heterojunction;

[0042] The first quantum dot 2 is formed between the end of the detection electrode 1 and the end of the gate electrode 3 , and the second quantum dot 4 is formed between the end of the gate electrode 3 , the end of the first electrode 5 and the end of the second electrode 6 .

[0043] More specifically, the first quantum dot 2 and the second quantum dot 4 are capacitively coupled.

[0044] In the specific implementation process, the number of detected single photons can be calculated by measuring the current in the first electrode 5. The current signal of the first electrode 5 is converted into voltage by a high-precision current-to-voltage converter 002, and the output voltage is then passed through a comparator 003. The comparator 003 sets a corresponding threshold. Since the current generated by the dark count is extremely small, the voltage after IV conversion is also very low. The comparison module allows the current-to-voltage signal generated by the detection of terahertz single photons above the threshold to pass through, and blocks the dark count signal below the threshold from passing through, thereby reducing the influence of the dark count on the terahertz single photon detector 001.

[0045] The capacitive coupling strength between the first quantum dot 2 and the single electron measuring device can be changed by changing the voltage on the second electrode 6. The gate electrode 3 is used to ensure the capacitive coupling between the first quantum dot 2 and the second quantum dot 4. Adjusting the voltage on the second electrode 6 can also adjust the size of the bound energy level in the second quantum dot 4.

[0046] More specifically, Figure 3 As shown, the integration module 004 includes a resistor R1, an operational amplifier and a capacitor C1;

[0047] The output end of the comparator 003 is connected to one end of the resistor R1, the other end of the resistor R1 and one end of the capacitor C1 are respectively connected to the inverting input end of the operational amplifier, the non-inverting input end of the operational amplifier is grounded, and the other end of the capacitor C1 and the input end of the processing module 005 are respectively connected to the output end of the operational amplifier.

[0048] In the specific implementation process, the voltage signal is input into the integration module 004 as Vin, and the integration module 004 integrates Vin over time and outputs Vout to the processing module 005. The voltage at the output end of the integration module 004 is:

[0049] More specifically, it also includes a digital-to-analog conversion module 006 ; the output end of the processing module 005 is connected to the input end of the terahertz single-photon detector 001 through the digital-to-analog conversion module 006 .

[0050] More specifically, the processing module 005 is FPGA.

[0051] In the specific implementation process, the FPGA determines the size of the calculated current and the number of detected single photons by processing the size of the voltage signal transmitted by the integration module 004, and can control the digital-to-analog conversion module 006 to generate a corresponding voltage to control the voltage on the second electrode 6, thereby controlling the capacitive coupling strength between the single electron measuring instrument and the first quantum dot 2, thereby controlling the sensitivity and noise coefficient of the terahertz single photon device.

[0052] According to the disclosure and teaching of the above specification, the technicians in the field of the utility model can also change and modify the above implementation. Therefore, the utility model is not limited to the specific implementation methods disclosed and described above, and some modifications and changes to the utility model should also fall within the scope of protection of the claims of the utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience and do not constitute any limitation to the utility model.

Claims

1. A terahertz single photon detection system, characterized in that: It includes a terahertz single photon detector, a current-to-voltage converter, a comparator, an integration module and a processing module; The terahertz single-photon signal enters the terahertz single-photon detector through the optical channel, the output end of the terahertz single-photon detector is connected to the input end of the current-voltage converter, the output end of the current-voltage converter is connected to the input end of the comparator, the output end of the comparator is connected to the input end of the integration module, and the output end of the integration module is connected to the input end of the processing module.

2. A terahertz single photon detection system according to claim 1, characterized in that: The terahertz single-photon detector includes a semiconductor heterojunction, a two-dimensional electron gas formed on the surface of the semiconductor heterojunction, a detection electrode formed on the surface of the semiconductor heterojunction, a first quantum dot and a single electron measuring instrument formed on the surface of the semiconductor heterojunction; the first quantum dot is formed between the detection electrode and the single electron measuring instrument.

3. A terahertz single photon detection system according to claim 2, characterized in that: The single electron measuring instrument is capacitively coupled to the first quantum dot.

4. A terahertz single photon detection system according to claim 2, characterized in that: The distance between the two-dimensional electron gas and the semiconductor heterojunction is 1nm-100nm.

5. The terahertz single photon detection system according to claim 2, characterized in that: The electron density in the two-dimensional electron gas is 1×10 11 cm -2 .

6. The terahertz single photon detection system according to claim 2, characterized in that: The single electron measuring instrument comprises a gate electrode, a second quantum dot, a first electrode and a second electrode formed on the surface of a semiconductor heterojunction; The first quantum dot is formed between the end of the detection electrode and the end of the gate electrode, and the second quantum dot is formed between the end of the gate electrode, the end of the first electrode and the end of the second electrode.

7. A terahertz single photon detection system according to claim 6, characterized in that: The first quantum dot and the second quantum dot are capacitively coupled.

8. The terahertz single photon detection system according to claim 1, characterized in that: The integration module includes a resistor R1, an operational amplifier and a capacitor C1; The output end of the comparator is connected to one end of the resistor R1, the other end of the resistor R1 and one end of the capacitor C1 are respectively connected to the inverting input end of the operational amplifier, the same-direction input end of the operational amplifier is grounded, and the other end of the capacitor C1 and the input end of the processing module are respectively connected to the output end of the operational amplifier.

9. The terahertz single photon detection system according to claim 1, characterized in that: It also includes a digital-to-analog conversion module; the output end of the processing module is connected to the input end of the terahertz single-photon detector through the digital-to-analog conversion module.

10. The terahertz single photon detection system according to claim 1, characterized in that: The processing module is FPGA.

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