Research On Free-Running Near-infrared Single-photon Detector And Laser Ranging Application

Laser ranging technology developed in the 1960s has been widely used in surveying,autopiloting,missile guidance,traffic management,and other fields for its advantages of high accuracy,long distance,high speed,high security,and portability.The photon counting laser ranging technology developed rapidly in recent years has advantages such as low power consumption,small size,high sensitivity,and simple data processing.The photon counting laser ranging system performs distance measurement by laser flight time.High-sensitivity detectors(single photon detectors)and time-of-flight recording instruments(time-to-digital converters)are two of the key components.A single photon detector capable of detecting a weak single-photon-level signal is advantageous in reducing the single pulse energy of the laser and reducing the size of the optical structure for photon receiving,and hence reduces the power consumption and size of the laser ranging device,and increases the maximum distance that the device can measure.The high-precision time-to-digital converter can accurately record the laser flight time and improve the accuracy of the laser rangefinder.This paper starts with two key components of photon counting laser ranging.A free-running single photon detector based on InGaAs(P)/InP APD and a high-speed,high-precision,eight-channel time-to-digital converter based on TDC-GPX were designed and fabricated.And then the photon counting laser ranging experiment was carried out.Based on the ranging experiment results,an optimized single photon detector was proposed and the development of the module was completed.A dedicated time digital conversion chip TDC-GPX and a USB 3.0 peripheral controller chip CYUSB3014 were used to achieve high speed and high precision in the design of the eight-channel time digital converter.The use of USB 3.0 protocol greatly improved the transfer speed of the design.The universal programmable ? interface of theUSB 3.0 controller was used to communicate directly with TDC-GPX.The design eliminated the need of the FPGA to bridge the two chips,reduced the complexity of the design and the cost of the device,and improved the stability and reliability of the device.The device is directly powered by USB 3.0 bus,and it is plug and play.The design improved the accuracy of TDC-GPX by increasing its core voltage.The final performance is as follows:octal-channel conversion accuracy 75ps,dual-channel conversion accuracy 25ps,maximum continuous readout speed 40Mcps,burst readout speed 182Mcps,with real-time point cloud diagram,real-time statistics of the histogram and the display of the two graphs.High-speed RF amplifiers,high-speed comparators,high-speed D flip-flops,monostable circuits,and level shifters were used to design the PCB board-level active quenching circuit,and a free-running near-infrared single-photon detector was designed based on InGaAsP/InP APD.Two-terminal quenching method was proposed to reduce the avalanche quenching time to 1.02 ns,which is better than the results in similar researches.The performance test results showed that at 223 K operating temperature,the detection efficiency is 10%with 1 ?s dead time.The dark count rate of the detector was about 640 Hz and the afterpulse probability was 39%.Photon counting laser ranging experiments were carried out using the designed free-running InGaAs(P)/InP SPD and high-speed,high-precision,eight-channel time-to-digital converter,and SPCM-AQRH-13-FC near-infrared-enhanced silicon SPD by Excelitas was also used for comparison.Laser ranging experiments of 150m,275m and 1.1km was completed.Comparative test results showed that the designed InGaAs(P)/InP SPD has a higher signal-to-noise ratio than the commercial Si-SPD and can detect farther distances using the same laser source.Based on the ranging experiment results,a miniaturized single photon detector device was proposed and designed.By introducing an integrated cooling packageand an improved thermal design,the cooling power consumption of the device is greatly reduced.By improving the performance of the active quenching circuit,the performance of the detector was enhanced and the circuit is simplified.Photon collection method was also optimized by using multi-mode fiber-coupling lenses-APD structure,and hence the single-photon detector was miniaturized to meet the requirements of laser ranging applications.