47results about How to "Reduce dark count" patented technology

The invention discloses an integrated gating active quenching/restoring circuit. The integrated gating active quenching/restoring circuit comprises a quick detection circuit, a pulse generation circuit, a pixel control circuit, a quenching circuit and a restoring circuit, wherein the quick detection circuit is used for processing a detected anode current signal of an SPAD (Single Photon Avalanche Diode) into a pulse signal, the pulse signal can be output through the pulse generation circuit, the pixel control circuit is controlled by an output signal and a gating signal of the pulse generation circuit, the restoring circuit and the quenching circuit are respectively controlled by outputs of the pixel generation circuit, outputs of the restoring circuit and the quenching circuit can be fed back to an anode of the SPAD, and the restoring and the quenching of the SPAD can be controlled. According to the integrated gating active quenching/restoring circuit disclosed by the invention, by adopting a gating control method, the dark counting rate of the SPAD can be effectively reduced, the quenching time can be controlled by the pulse generation circuit, and the integrated gating active quenching/restoring circuit has the advantages of compact area and low power consumption.

The invention relates to the fields of quantum secret communication, weak ultrared detection, and the like, and provides an impulse gate-control low-pass filtering ultrared single-photon detector. Theimpulse gate-control low-pass filtering ultrared single-photon detector comprises an impulse gate-control power source, an In-Ga-As-In-P avalanche photodiode circuit, a DC voltage baising circuit, alow-pass filter, a high-speed wideband amplifier, a ultra-high-speed comparator and a counter, wherein gigahertz (GHz) impulse signals output by the impulse gate-control power source are used as gatecontrol signals of the In-Ga-As-In-P avalanche photodiode circuit, and spike noise signals caused by the junction capacitance differential effect of In-Ga-As-In-P avalanche photodiodes by the low-passfilter are used for filtering in a low-pass mode. The gigahertz impulse gate-control low-pass filtering ultrared single-photon detector solves the problem of spike noise interference in the prior art, increases the detection sensitivity of the avalanche signals and can be used for detecting GHz high-speed ultrared photon.

The invention provides a single-photon avalanche diode quenching circuit based on an offset control differential amplification structure. A gate control circuit is used for receiving a gate control enable signal input externally to be in the closed or opened state. A rapid reset circuit is used for receiving a reset signal input externally while the gate control circuit is in the opened state so that the gate control circuit can be in the closed state. When an SPAD detects that a photon generates avalanche current, the avalanche current flows through a detection resistor to generate voltage drop. A low voltage detection circuit adopts the differential amplification structure based on offset control and is used for inducting changes of the input end voltage; when the input end voltage is larger than a detection threshold value of the low voltage detection circuit, output end signals become low-level signals, the detection resistor is controlled to be switched off, and meanwhile a rapid quenching circuit is closed; the rapid quenching circuit is used for accelerating the quenching process when closed, so that the avalanche current is quenched. In the quenching circuit, the detection threshold value of the quenching circuit can be smaller than the turn-on voltage of an NMOS transistor.

The invention provides a high polarization ratio single photon detector based on superconductive nanowires. The high polarization ratio single photon detector based on the superconductive nanowires comprises a substrate, an anti-reflection layer and the superconductive nanowires, wherein the anti-reflection layer is combined to the surface of the substrate, the superconductive nanowires are combined to the surface of the anti-reflection layer in a periodic winding structure, the width of the superconductive nanowires is not larger than 75 nanometers, the thickness is not larger than 7 nanometers, and the duty ratio is not larger than 40 percent. According to the high polarization ratio single photon detector based on the superconductive nanowires, the width, the thickness and the duty ratio of the superconductive nanowires of the single photon detector are adjusted, and a large polarization ratio of the single photon detector is achieved. Compared with a traditional polarization detector, the high polarization ratio single photon detector based on the superconductive nanowires has the advantages of being small in size, simple in structure, high in sensitivity, low in dark counting and the like, and external integration of polarization devices is not needed.

The invention discloses an optical fiber temperature and strain sensing device based on a high spectral resolution technology. The optical fiber temperature and strain sensing device comprises an optical transmitting system, an optical fiber sensing system, a high spectral resolution scanning system, an optical filtering system, a data acquisition system and a control system. The invention further discloses an optical fiber temperature and strain sensing method based on a high spectral resolution technology. According to the invention, temperature and strain carriers based on optical fiber brillouin scattering are used for the distributed sensing of temperature and strain; a narrowband reflective tunable Bragg grating is used for filtering out optical fiber brillouin back scattering, a cavity length-tunable Fabry-Perot interferometer is used for the full spectrum scanning of optical fiber brillouin scattering spectrum, a single photon technology is used for detecting a back brillouin scattering signal in the optical fiber; the invention has the advantages that the structure is simple, s the stability is high, compared with coherent detection, the signal detection and processing difficulty and complexity are reduced, and the detection distance resolution and accuracy are improved.

The invention discloses high atmosphere detection laser radar based on a large-photosurface superconducting single-photon detector. By application of the large-photosurface superconducting single-photon detector to a high atmosphere detection laser radar system, high atmosphere parameter detection can be realized through increase of telescope area. Compared with an existing detector applied to the high atmosphere detection laser radar, the superconducting single-photon detector has advantages of large photosurface, high counting rate, high quantum efficiency, low dark count rate, high photon count rate and short jittering time. Therefore, the high atmosphere detection laser radar based with the large-photosurface superconducting single-photon detector is more advantageous in range resolution, spatial resolution and detection precision; in other words, under the condition of realizing same detection indexes, the laser radar with the large-photosurface superconducting single-photon detector can adopt a smaller-aperture telescope or a lower-power laser.

The invention discloses a near-infrared band low-noise free-running single-photon detector, and the detector comprises a negative feedback avalanche photodiode (NFAD), a peripheral circuit of the NFAD, a refrigeration box, a discrimination module, a dead time setting module, a temperature adjustment module and an FPGA; The NFAD and the peripheral circuit are respectively connected with the FPGA through the discrimination module and the dead time setting module. The discrimination module is used for converting an avalanche signal into an electrical level signal and transmitting the electrical level signal to the FPGA. The dead time setting module is used for reducing the bias voltage of the NFAD below an avalanche voltage. The NFAD and the peripheral circuit are packaged in the refrigeration box, and the refrigeration box is connected with the FPGA through the temperature adjustment module. According to the scheme of the invention, the detector carries out the deep refrigeration of the NFAD through a Stirling refrigerator, thereby reducing the dark count of the detector. The post-pulse probability of the detector is effectively inhibited through integrating a single thin resistor in a detector part and setting the dead time after each detection event.

The invention provides a wavelength up-conversion semiconductor structure and an optical detection method thereof, belonging to the semiconductor material and device preparation field. The wavelength up-conversion semiconductor structure is characterized in that: the wavelength up-conversion semiconductor comprises at least two quantum well layers and a barrier layer between the two layers, energy difference between an electrical excitation state energy level in a quantum well layer-1 and an electrical ground state energy level is corresponding to infrared photon energy, and energy differencebetween an electrical ground state energy level in a quantum well layer-2 and the electrical excitation state energy level in the quantum well layer-1 is less than 50meV. According to the invention, a dark count introduced in a wavelength up-conversion process can be greatly reduced. The invention provides an infrared low-light detection method based on the wavelength up-conversion semiconductor structure, and is characterized in that: when an infrared photon is absorbed, an electron at a ground state energy level in the quantum well layer-1 moves to an excitation state energy level and enters the quantum well layer-2 through resonance tunneling, and an electron cavity carries out recombination emission of a low wave length photon which can be detected by an optical detector with an extremely dark count.

The invention provides a single-photon Si-APD detector, which comprises an absorption region, a P+ contact region, an N+ contact region, an avalanche region and a dielectric layer. The absorption region is arranged in the middle of the surface of a P-type substrate; the P+ contact region is arranged under the absorption region; and a lower electrode is arranged under the P+ contact region. Cut-offrings are arranged at the two ends of the upper portion of the absorption region. The avalanche region is arranged in the middle of the upper portion of the absorption region and is formed through compensation doping of P-type impurities and N-type impurities. The N+ contact region is arranged on the avalanche region. The two sides of the avalanche region are each provided with a protection ring,and an upper electrode is arranged above the protection ring. The dielectric layer is arranged on the N+ contact region. The single-photon Si-APD detector has the relatively wide avalanche region andintroduces few defects in the manufacturing process, and can realize device performance of high detection efficiency and low dark counting.

The invention provides a single-photon avalanche photodetector and a preparation method thereof, and the single-photon avalanche photodetector comprises a substrate; a multiplication layer which covers the substrate, wherein a charge layer is formed on the multiplication layer; a first silicon dioxide layer which covers the charge layer and part of the multiplication layer, wherein an epitaxial window is formed in the first silicon dioxide layer; a light absorption layer which is arranged in the epitaxial window, wherein a doping layer is formed on the light absorption layer; a second silicon dioxide layer which covers the surfaces of the doping layer, part of the light absorption layer and the first silicon dioxide layer, wherein an electrode window is formed in the second silicon dioxide layer, and part of the doping layer is exposed; an electrode which comprises a p electrode and an n electrode, wherein the p electrode is arranged in the electrode window, and the n electrode is arranged on the back surface of the substrate; and an anti-reflection layer which covers the second silicon dioxide layer, the p electrode and the doping layer, wherein the width of the charge layer is larger than that of the doped layer.

The invention provides a micro-nano optical fiber-waveguide-superconducting nanowire single-photon detector and a preparation method thereof. A micro-nano optical fiber fixed in a V-shaped groove can realize high-precision optical coupling alignment with a waveguide, and the transition section, which becomes thin from thick, of the micro-nano optical fiber is suspended, so that light is prevented from leaking to a substrate, and the loss in the optical transmission process is further reduced; the waveguide type superconducting nanowire structure can completely absorb light on a chip; due to the design of the corner waveguide, an optical coupling area of the micro-nano optical fiber-waveguide can be completely separated from an optical detection area of the waveguide type superconducting nanowire structure, dark counting caused by background radiation propagating along the optical fiber can be effectively reduced, and the influence of the background dark counting on optical detection is reduced; according to the invention, a single-photon detector integrating high detection efficiency, high counting rate, low time jitter and low dark counting can be realized, and the detector is expected to play a role in the fields of light quantum information processing, quantum optics and the like.

The invention provides a high-efficiency single-photon detection system and method applied to an area array up-conversion camera. The system at least comprises a core processing module, an active quenching module, a rapid recovery module, an adjustable high-voltage module, an adjustable medium-voltage module, a counting signal processing module and a protection module. The core processing module is configured to enable the avalanche diode to work in a Geiger mode through the adjustable high-voltage module, acquire an avalanche signal of a cathode of the avalanche diode through the counting signal processing module, and perform active quenching control of the avalanche diode through the active quenching module and the adjustable medium-voltage module. The avalanche diode is quickly recovered to Geiger mode control through the quick recovery module; the protection module is configured to control the connection between the active quenching circuit and the avalanche diode according to a voltage signal generated by the avalanche signal on the sampling resistor; the dark counting is reduced, the detection efficiency is improved, and the saturation counting rate is improved.

The invention discloses an integrated low-delay active quenching near-infrared single-photon detector, which comprises an active quenching circuit and an active recovery circuit, the active quenchingcircuit comprises an APD chip, a reverse amplifier, a high-speed comparator and an identification level adjusting circuit, the anode of the APD chip is connected to the forward input end of the high-speed comparator through a balance capacitor Cc, and meanwhile the anode of the APD chip is connected to the direct-current bias control circuit; the cathode of the APD chip is divided into two paths,one path is connected to the reverse input end of the high-speed comparator and the identification level adjustment circuit through the balance resistor R and the balance capacitor Cd1, and the otherpath is connected with the quenching transistor bias circuit; the forward output end of the high-speed comparator is connected with the reverse amplifier to generate a quenching signal and send the quenching signal to the cathode of the APD chip; the active recovery circuit controls a pulse trigger for the FPGA, and the pulse trigger is connected with the forward enabling end of the high-speed comparator. The detector has the advantages that the USB power supply circuit can be directly powered by a USB, and has low post-pulse probability and strong practicability in the case of low dead time and high detection efficiency.

The invention relates to the field of fiber bragg grating signal demodulation, and in particular, relates to a high-precision fiber bragg grating signal demodulation system which comprises a pulse driving source, a laser, a circulator, a fiber bragg grating sensor, an adjustable attenuator, a single-photon detector, a time-to-digital converter and an information processor. The fiber bragg gratingsignal demodulation method comprises the following steps that: step 1, a laser device emits lasers with different wavelengths, and the lasers reach the fiber bragg grating sensor through the circulator and are reflected to the single-photon detector; step 2, the time-to-digital converter measures a single-photon counting value reaching the single-photon detector; step 3, the information processorobtains a measurement signal according to the single photon counting value measured by the time-to-digital converter, and the measurement signal change amount of the two reflected pulse light reachingthe single photon detector can be obtained according to the measurement signal; and step 4, the drift amount of the reflection center wavelength of the fiber bragg grating is demodulated according tothe change amount of the measurement signal. The problem that in an existing detection mode, the physical quantity of the fiber grating sensor cannot be accurately measured is solved.

The invention relates to the field of photoelectric detection, in particular to a gated silicon-based visible near-infrared single-photon detection device which comprises a direct-current high-voltage power supply, a radio-frequency transformer, a high-speed CMOS driver, an FPGA, a high-speed comparator, a human-computer interaction interface and a silicon-based visible near-infrared single-photon detector SAPD. The direct-current high-voltage power supply is connected in series with the inductor and the current-limiting resistor and then is connected with an N pole of the silicon-based visible near-infrared single-photon detector SAPD. The high-voltage gating pulse with short rising and falling time can be generated, the dark counting and post-pulse probability can be effectively reduced while the single-photon detection efficiency is improved, peak noise caused by the front edge and the rear edge of the gating pulse can be effectively filtered out, counting of avalanche signals is achieved, meanwhile, the width, the amplitude and the repetition frequency of the gating pulse can be adjusted, and working points can be conveniently adjusted for different silicon-based visible near-infrared single-photon detectors, so that the performance is better.