Geiger-mode Avalanche Photodiodes Research Articles

Detection efficiency for underwater coaxial photon-counting lidar.

Backscatter has significant influence on detection efficiency for underwater lidar, especially for coaxial photon-counting lidar using a Geiger-mode avalanche photodiode. In this paper, based on our underwater coaxial photon-counting lidar structure and volume scatter function, a detection model with consideration of backscatter and refraction indices is proposed. Using this detection model, analysis of the detection efficiency is conducted. It reveals that in an underwater environment, higher pulse energy or a closer target range is not necessarily helpful for a higher target detection probability, which is vastly different from our traditional concepts. For example, the detection probability for a 5 m target would be 0.76 using a 200 pJ pulse and 0.55 using a 1000 pJ pulse for our coaxial photon-counting lidar. Monte Carlo simulation is conducted to verify our model and analysis, and some practical methods for improving the target detection probability in an underwater environment are proposed.

Lattice-Constrained Stratified Sampling for Point Cloud Levels of Detail

In the last several years, airborne topographic light detection and ranging (LiDAR) has emerged as an important remote-sensing technology supporting a wide variety of applications. In that time, researchers have conducted studies to determine the optimal sampling densities required to support their respective applications. This natural progression of experimentation and analysis has resulted in several recommended sampling density stratifications for LiDAR point cloud products. Recognizing the need for point clouds of varying sample densities provides at least two motivations for creating level of details (LOD) for high-resolution point clouds. First, from the perspective of LiDAR data consumers, there is a desire to use the coarsest sampling that supports the application to reduce procurement costs, storage constraints, and processing times. Second, from the perspective of LiDAR data providers, there is a desire to collect data once at the highest supported fidelity to minimize recollection costs and redundancy in data holdings. In this article, we present an approach for generating point cloud LODs by constraining samples to regular discrete lattices to optimize the coverage of the volumes represented by each sample. We compare our approach to the two most common point cloud sampling methods: random sampling and rectangular lattice sampling. We discuss two approaches for representing the point cloud LODs. Finally, we propose an extension of our sampling approach for processing single-photon and Geiger-mode avalanche photodiode (GmAPD) LiDAR.

Signal extraction algorithm of Gm-APD lidar with low SNR return

Geiger mode Avalanche Photo Diode(Gm-APD) laser radar in the case of high background noise during the daytime causes the peak of data distribution is firing by the noise but not the signal, this phenomenon leads to difficulty in extracting the peak characteristics of the signal, lost target pixels of three-dimensional range image and the low image signal-to-noise ratio by using the traditional non-parametric estimation signal extraction algorithm. Aiming at this problem, the bump hunting combination algorithm(BHC) is proposed, which extracts echo signal position under low SNR echo data, removes noise pixels and provides favorable conditions for target recognition by combining the convex features of echo signals and pixelwise cross correlation. According to the experimental results, when using 500 frames of echo data, BHC improved 15.10 % of the target reduction degree and 21 times of the image signal-to-noise ratio compared peak-picking method, increased 3.83 % of the target reduction degree and 15 times of the image signal-to-noise ratio compared the maximum likelihood estimation(MLE) algorithm.

Three-Dimensional Laser Imaging Based on a Photon-Counting Avalanche Photodiode Array

Photon-counting detector array is very desired for high-resolution laser imaging based on direct time-of-flight measurement. Such systems have potential applications in remote sensing with long distances. We will perform three-dimensional imaging using a large InGaAs Geiger-mode avalanche photodiode array which has single-photon sensitivity. To improve the image quality with only a few photon detections, the photon counting imaging process is analyzed and a regularization method based on pixel spatial correlation is employed for image reconstruction. The performance of the method is compared with that of conventional maximum likelihood estimation on intensity and range image reconstructions of a building about six hundred meters away.

基于盖革APD阵列的光子计数三维成像

基于盖革APD阵列的光子计数三维成像

Effect of optical-scattering characteristics with modified kernel-based model on the triggering probability of Gm-APD

It is not feasible to use the Geiger-mode avalanche photodiode (Gm-APD) detection model to guide detection quantitatively during daytime, because of the incompletely built echo intensity model. In this study, because the background noise and the signal light are both modulated by the target's optical-scattering characteristics (OSCs), a hybrid light-scattering model (the modified kernel-based bidirectional reflection distribution function (BRDF) model) is substituted in the laser detection and ranging (LADAR) ranging equation. In such a BRDF model, the Li-Liang-BRDF model is taken as the kernel, and the background noise equivalent intensity coefficient is employed to link the background noise part to the laser echo part. According to the results of a Gm-APD outdoor experiment, the proposed LADAR ranging equation is applicable to detection during daytime, and the noise scaling factor d(θs) is not a constant with the variation of solar zenith angle; the signal intensities in the theoretical and experimental results only exhibit a difference of 5%. The effects of various factors (e.g., solar zenith angle, LADAR observation angle, and different target materials) on the echo signal-to-noise ratio and triggering probability are analyzed by the proposed LADAR ranging equation. Moreover, a maximum-likelihood estimation-based theoretical method is proposed to calculate the maximum detection range during daytime. Subsequently, the change law of the detection range in daytime is analyzed, and the calculated detection range of the developed Gm-APD LADAR reaches 3.5 km under an actual daytime background. This study can provide theoretical support and formulates several strategies for Gm-APD detection in daytime. Furthermore, novel ideas can be proposed to calculate theoretically the effective detection range of Gm-APD LADAR.

Photon counting polarization imaging strategy for target classification under photon-starved environments

Considering the requirements of long-range detection, eye safety and anti-reconnaissance, the detection of weak signal has become a research hotspot in the field of lidar. Gm-APD(Geiger-Mode Avalanche Photodiode) has extremely high response sensitivity and extremely high timing accuracy. At present, Gm-APD photon counting lidar system can obtain the 3D (Dimension) range image of target in the case of weak echo signals. However, considering the detection of obscured target, the 3D range image cannot distinguish which pixel point echoes come from the target and which come from the shelter, which will cause the target recognition to be blurred and uncertain. In this paper, a Gm-APD photon counting polarization imaging lidar system is proposed, which can simultaneously obtain the range and polarization information of the target under the condition of the extremely weak echo optical signals (the number of photons per pulse echo is much less than 1). Finally, the experimental system was built to image a model airplane shaded by tree branches, with an average of 0.01 photons per echo pulse, a clear image of model airplane is separated from the shelter according to polarization information.

Ranging performance models based on negative-binomial (NB) distribution for photon-counting lidars.

For photon-counting lidars, the current ranging performance models are based on Poisson statistics that are a special case of a negative-binomial (NB) distribution. In this paper, a new ranging performance model that considers the effect of a target's speckle, the noise, and the dead-time of photon-counting detectors is derived from the NB distribution. The derived ranging performance model is verified by both an experiment based on a Geiger mode avalanche photodiode (GM-APD) lidar and a simulation using the recursive method. The ranging performance model is then used to analyze the effect of target speckle for two typical photon-counting ranging systems aimed at different types of target: the space-borne Ice, Cloud and land Elevation Satellite-2 (ICESat-2) for detecting the Earth's surface, and the ground-based laser ranging system at Shanghai Astronomical Observatory (SHAO) station for detecting space debris. The results indicate that for space-borne or airborne lidar, the ranging performance model can be approximated to the classic models based on Poisson statistics, but for a ground-based laser ranging system, the approximation model introduces differences of ~1 cm in ranging bias and 4.8 cm in ranging precision from the theoretical model of the NB distribution. In addition, the new model is universal because it is compatible with the classic model of a Poisson distribution, i.e., when the speckle diversity is greater than 100, the result calculated from the new model is identical to the classic model.

Single photon detector with a mesoscopic cycling excitation design of dual gain sections and a transport barrier.

Conventional semiconductor single photon detectors (SPDs) are Geiger-mode avalanche photodiodes made of high-quality crystalline semiconductors and require external quenching circuits. Here we report a design of an SPD having dual gain sections to obtain mesoscopic cycling excitation and an amorphous/crystalline heterointerface to form an electron transport barrier that suppresses gain fluctuations. The dual gain sections comprise a crystalline silicon n/p junction and a thin layer of amorphous silicon. At 100MHz, the device shows single photon detection efficiency greater than 11%, self-recovery time of less than 1ns, and an excess noise factor of 1.22 at an average gain around 75,000 under 8.5V bias.

A reconstruction method for restraining range walk error in photon counting Lidar via dual detection

The fluctuation of the intensity of echo-pulses introduces a range walk error (RWE) to a photon counting Lidar. In this paper, we present a reconstruction method without priori modeling to restrain the RWE and improve the ranging accuracy. The presented method is implemented by separating the echo-pulses into dual Geiger-mode avalanche photodiodes (Gm-APDs) then reconstructs the distribution of signal photoelectrons based on the Poisson probability response model. The presented method is theoretically analyzed by Monte Carlo simulation. The experimental results show that the RWE is reduced from −33.7 to −2.7 mm and depth precision is improved from 14.8 to 3.6 mm.

Extended short-wave infrared linear and Geiger mode avalanche photodiodes, based on 6.1 Å materials

Extended short-wave infrared (SWIR) avalanche photodiodes based on III–V quaternary alloys were grown on GaSb. An InGaAsSb absorber allowed for cut-off wavelengths of 2.2 μm and 2.75 μm, at 77 K and 300 K, respectively. A multiplication layer of AlGaAsSb with Al = 0.9 mole fraction was used, a material recently characterized by our group, allowing for a breakdown voltage of less than 15 V. Linear and 2D arrays were fabricated using BCl3 dry and HF wet-chemical etching, and dielectric passivation layers were tested. These results indicate that extended SWIR single photon detectors can be developed.

Status and perspectives of solid state photon detectors

Abstract Development of solid state photon detectors is a mature field of engineering and technology based on well-established grounds of solid state physics, and, in the same time, a frontier area of research and innovations faced with dramatic challenges. The ultimate challenge for the modern developments is a detection of optical signals at a quantum level – resolving arrival time and spatial location of individual photons – to realize a formula “every photon counts”. To succeed, the developments are focused on improvements in three directions: threshold sensitivity and photon number resolution, fast timing and time resolution, and fine granularity imaging with fast readout. There are many inherent trade-offs to be resolved in each direction. Development of Silicon Photomultiplier (SiPM) is considered as one of the most promising innovations toward “near ideal” photon detector. SiPMs of various designs have been developed in the 1990s–2000s in Russia, and their unique performance in the photon number and time resolution has been demonstrated and recognized in the mid-2000s. Now SiPMs are widely implemented in nuclear medicine, high energy physics, astrophysics , and Cherenkov light detection. However, developers of Geiger Mode APD or SPAD arrays based on active quenching also found new approaches and opportunities for considerable improvements using modern CMOS technology, namely: reduction of a dead space occupied by electronics, multiplexing readout architecture, backside illumination, and 3D integration of photosensor and electronic layers (3D digital SiPM). Detection of Cherenkov light is one of the most challenging applications for photodetectors . Superior photon number resolution starting from single photons, picosecond-scale time resolution, and large-area imaging are typical requirements, and all these highly demanded capabilities are contradictory. This report presents overview and analysis of the state-of-art in the modern solid state photon detectors as well as their potential and perspectives to meet the quantum imaging challenge.

Receiver performance characteristics of single-photon lidar in a strong background environment.

The detection performance of the single-photon lidar (SPL) receiver is investigated as a function of optical attenuation and superconducting nanowire single-photon detector (SNSPD) parameters (detection efficiency and dead time) in a strong background environment. With detection theory, it is found that there is optimal attenuation to make detection probability the highest at a given false alarm probability, namely, optimal working conditions. Optical attenuation is proved to be required only when the background photon number is higher than a certain value; otherwise, it is not necessary. Furthermore, the performance of a Geiger-mode avalanche photodiode (GMAPD) is compared. Under optimized working conditions, the SNSPD-based receiver exhibits higher detection performance in a strong background environment than that of the GMAPD-based receiver due to shorter dead time, while in a low-noise environment, attenuation is not essential, and detection efficiency becomes the dominant factor. The theoretical result gives a reference for the SPL receiver system design to achieve optimal detection performance.

Research of detecting the laser’s secondary reflected echo from target by using Geiger-mode avalanche photodiode

Abstract When the Geiger-mode avalanche photodiode (Gm-APD) laser detection and ranging (LADAR) carries out the air-to-ground detection, it can detect the echo that is successively reflected by targets and the ground, which causes the false target in the image obtained by the LADAR. In this paper, the echo which is successively reflected by two surfaces is called the secondary reflected echo, and the echo which is just reflected once is called the single reflected echo. Considering the Gm-APD’s superior ability to detect photon, we investigate and analyze the triggering characteristics of the Gm-APD for detecting the secondary reflected laser echo from the targets, also, we carry out the experiments on detecting the secondary reflected echo in near field and far field by using array Gm-APD to verify that the array Gm-APD can effectively detect the secondary reflected echo, and this paper lays the foundation for the research of the secondary reflection’s influence on the images obtained by Gm-APD. In this paper, firstly, we use the echo triggering model, which contains LADAR ranging equation and Poisson probability model, and the Monte Carlo simulating method to completely verify the possibility of detecting the secondary reflected echo by using Gm-APD, in theory. The theoretical results show that Gm-APD can detect the secondary reflected echo, and the wider the field of view(FOV) is, the longer the detecting range is, besides, the higher the LADAR is located at, the lower the target’s secondary reflected echo’s intensity is and the higher the ground’s single reflected echo’s intensity is; then, using the Gm-APD with an array of 64 × 64 and 32 × 32 to detect the indoor scene and the moving van in far field, respectively, the results show that the indoor experiment obtains the complete first and second reflected image and the single pixel can detect the secondary reflected echo from multiple targets, also, for the far-field experiment, the single reflected echo and second reflected echo can be obtained in a single frame image, and under this experimental conditions, two pixels which are studied, realize the range extension of 25.6 m and 41.9 m respectively, which shows that the Gm-APD can likely detect the false target in the far field; finally, the methods that finding the secondary reflected surface by using the multiple-frame statistics for static targets and the image of triggering position in chronological order for moving targets, respectively, are proposed to eliminate the secondary reflected image. This article can provide some theoretical references for eliminating the secondary reflection before target recognition.

Photon-counting panoramic three-dimensional imaging using a Geiger-mode avalanche photodiode array

A lidar system based on a photon-counting Geiger-mode avalanche photodiode (GmAPD) array can provide high range resolution three-dimensional imaging. The small number of pixels in the GmAPD array limits the size of measured scenes compared to passive cameras. Here, the performance of rapid panoramic imaging of larger scenes is investigated. Controlled environment indoor measurement at up to 24 m range is used to validate the principle. Outdoor daylight measurements of natural targets at 230 to 340 m range are performed to test the capability of the measurement system. A 20 deg by 1.8 deg scene is imaged with 0.25-mrad lateral resolution in 4 s. The standard deviation of point to plane distances for a flat wall in the outdoor measurement is 10.6 mm, giving an estimate of the achievable relative range accuracy, even if this will depend on the signal-to-noise ratio. A radiometric model is used to estimate the performance of an upgraded optimized system and the necessary laser power for imaging at longer ranges in both day and night conditions.

Research on the optimal optical attenuation in a laser radar using a Geiger-mode APD

For a laser radar (LADAR) system using a Geiger-mode avalanche photodiode (GmAPD), attenuating echo and background noise simultaneously affect the original data output from the GmAPD and eventually affect detection performance. In this study, we established a model that applies to the GmAPD-based LADAR with optical attenuation and also applies to any typical single photon detector that has a dead time (e.g.,the photomultiplier tube); thus, a comprehensive and fundamental study is performed for the mathematical expectation of the number of signal detections (ES), the mathematical expectation of the number of noise detections (EN), the signal-to-noise ratio (SNR), and the range bias (absolute error, Rb) and precision (standard deviation, Rp) under various attenuation levels with different dead times and signal noise conditions. We observed the following: on the one hand, there exists an optimum attenuation level at which ES and SNR are maximized; on the other hand, there exists another optimum attenuation level for shorter dead times, at which Rp is minimized. The phenomenon of the maximum ES, SNR, or minimum Rp disappears gradually as the echo or noise decreases from high levels (e.g.,10 photoelectrons/echo or an equivalent background noise of 10 photoelectrons/range gate). Further, higher attenuation, which shows advantages under strong echo or noise conditions, yields a larger improvement in ES for longer dead times; and, with the reduction of the dead time or the noise, the maximum ES gradually increases, and the corresponding optimum attenuation level becomes slighter. Additionally, we found that, as the optical attenuation increases, EN decreases to 0, Rb changes from a negative value to 0, and Rp is minimized, becomes slightly worse, and reaches a constant. Moreover, the shorter dead times, which show advantages when they are shorter than the end time of the echo, lead to a larger ES, better Rb, and slightly worse Rp than the longer ones.

Detection performance improvement of photon counting chirped amplitude modulation lidar with response probability correction**Project supported by the Fundamental Research Funds for the National Defense Basic Scientific Research, China (Grant No. JCKY2016603C007).

Geiger mode avalanche photodiode detector (Gm-APD) possesses the ultra-high sensitivity. Photon counting chirped amplitude modulation (PCCAM) light detection and ranging (lidar) uses the counting results of the returned signal detected by Gm-APD to mix with the reference signal, which makes PCCAM lidar capable of realizing the ultra-high sensitivity, and this is very important for detecting the remote and weak signal. However, Gm-APD is a nonlinear device, different from traditional linear detectors. Due to the nonlinear response of Gm-APD, the counting results of the returned signal detected by Gm-APD are different from those of both the original modulation signal and the reference signal. This will affect the mixing effect and thus degrade the detection performance of PCCAM lidar. In this paper, we propose a response probability correction method. First, the response probability correction model is established on the basis of Gm-APD Poisson probability response model. Then, the response probability correction model is used to adjust the original modulation signal that is used to drive laser, in order to make the counting results of the returned signal detected by Gm-APD better mix with the local reference signal in the same form. Through this method, the detection performance of PCCAM lidar is enhanced efficiently.

Error performance analysis of a non-ideal photon counting array receiver system for optical wireless communication.

In order to detect weak light from background radiation, utilizing an array of Geiger-mode avalanche photodiodes (GM-APDs) as a detector in the receiver is researched. First, the principle of a GM-APD operated in gated mode is analyzed. Based on the Poisson random process of arrival of photons, the trigger probability of a single GM-APD has been computed. Then, according to the trigger probability, a new bit error rate (BER) model of a photon-counting array receiver system is built, and the expression of BER is derived based on the quantum efficiency, signal photons, background photons, dark carriers, and the number of GM-APDs in array. Using the BER expression, the error performance of a new photon-counting array receiver system can be predicted rapidly. Furthermore, the error performance of a system based on an array of GM-APDs is investigated. The simulation results indicated that maintaining the ratio of signal photons and background photons above 1 is necessary for system operation. When background noise is limited to the acceptable range, maintaining a certain scale of GM-APDs (above 20) in array can greatly reduce the demand of transmitting power. Compared with achieving target BERs of 10-6 and 10-9, preserving a BER of 10-3 and making use of error correction coding can further improve the receiving sensitivity to 5-8dB.

Theoretical ranging performance model and range walk error correction for photon-counting lidars with multiple detectors.

Ranging performance is the key indicator for a ranging lidar system, and a theoretical ranging performance model can be used for optimizing systematic parameters when designing a lidar system. The fluctuation of the signal photon numbers introduces range walk error to photon-counting lidars that can be as high as tens of centimeters. In this paper, based on the lidar equation and the statistical property of photon-counting detectors, a theoretical ranging performance model for photon-counting lidars with multiple detectors is first derived. Next, a theoretical correction method for offsetting range walk error is proposed, as verified by experiments using a Gm-APD (Geiger mode avalanche photodiode) lidar system. The results indicate that multiple detectors are very useful to maintain a consistent ranging precision when the mean received signal photons are variable. With a 1600 repetitive ranging measurement, the new method can achieve a centimeter ranging accuracy, with a mean and standard deviation of the residual errors of 1.14 cm and 1.23 cm, respectively. This new method is potentially suitable for a satellite photon-counting lidar system such as ICESat-2, as only a certain number of repetitive measurements, the time tag, and a certain number of triggered detectors are required to offset the range walk error.

Simple Monte Carlo Simulator for Modelling Linear Mode and Geiger Mode Avalanche Photodiodes in C++

Linear mode and Geiger mode Avalanche Photodiodes are widely used to detect weak optical signals, with the latter able to detect a single photon at a time. Practical simulators for these devices should accurately produce relevant device characteristics and not be overly computationally intensive. The Simple Monte Carlo Simulator, written in C++, offers such a combination and can simulate avalanche photodiodes made with Silicon, Gallium Arsenide and Indium Gallium Phosphide, with the potential to include other semiconductor materials. The software is available on The University of Sheffield Research Data Catalogue and Repository at https://doi.org/10.15131/shef.data.5683939 and on GitHub at https://github.com/jdpetticrew/Simple-Monte-Carlo-Simulator.