The comparative characteristics of highly sensitive photodetectors for modern lidar systems, like self-driving vehicles and autonomous systems for collision avoidance, sensors for aircraft and marine vessels, atmospheric lidar sensing systems, topographic mapping tools are considered. Estimates of the basic parameters of photodetectors such as sensitivity threshold, dynamic range, time and amplitude resolution, as well as the effect of background light on sensitivity were made for the new-type experimental detector HD-SiPM (high-density silicon photomultiplier) and compared with the APD module and commercial SiPM devices, optimized for ToF LiDAR application. Comparison results show that the HD-SiPM looks promising for application in various ToF LiDAR systems.

In this paper, we analyze the influence of the crosstalk level and the dynamic range on the basic characteristics of a silicon solid-state photomultiplier and demonstrate their importance for detecting of optical signals with backlight illumination, in particular, for LIDAR application. Experimental results obtained in the study of threshold and fluctuation parameters of detectors with different levels of crosstalk and dynamic range are presented. It is shown that the detector design combining a high dynamic range with a small crosstalk gives a noticeable advantage in such applications.

The new-type silicon photomultiplier with high density of cells (HD-SiPM) was developed by DEPHAN for the task of analog detecting of short light pulses. In this work we have tested and compared with known references its responsivity, amplitude and time resolution by short laser pulses (442 nm) in a wide range of signal intensities. The results demonstrate, that the new detector could be interesting for Hi-Res Medical Imaging and other pulse detecting applications in nuclear science, especially those requiring combination of sensitivity, high speed and dynamic range from a small-area detector or an array element.

DEPHAN detector is a prototype of a new-type silicon photomultiplier (HD-SiPM) with the amplifying channels (cells) integrated into solid photosensitive area. The new proposed design enables to increase cell density (4.5.10(4) per sq. mm) and significantly widen dynamic range of the detector preserving or even improving its fill factor (>80%) and cross-talk probability (<2%). Threshold sensitivity of the "LiDAR-emulating" system for red and NIR wavelength, its dependence on background illumination, and other key characteristics were measured with the DEPHAN detector and reference detectors (APD, SiPM). Results confirm prospects of the new-type detector for ToF-LiDAR and 3D-imaging systems.

One of the most important problems of detecting weak light pulses is the determination of the accurate signal transit time. In this case, photodetectors capable of detecting single photons are characterized by two main parameters: the photon detection efficiency and transit time spread. A unified technique for measuring these parameters is proposed. The technique is based on the probabilistic distribution of transit times, which allows separation of characteristics of single-photon processes as multiphoton light pulses are fed and under conditions of high dark noises, which seems important, in particular, when operating with solid-state photomultipliers.

The precision measurement of the weak light pulse arrival time seems to be really important for various time-of-flight applications within the high energy physics and the medical imaging areas. Photon Detection Efficiency (PDE) and single photon Transit Time Spread (TTS) are considered to be the key characteristics for time resolution responsible photodetectors within such applications. The measurements of PDE and TTS are rather independent and require different techniques and setups. We consider the probability of single photon detection as a defective cumulative distribution function (CDF) of the single photon transit time, so a number of analytical expressions of how it can be reconstructed from the multi-photon TTS histogram affected by the dark counts have been found. It has allowed us to suggest a robust quantitative method of a single photon detection characterization provided with both single photon TTS and PDE. The method is considered to be especially relevant and useful for the Solid State Photomultipliers (SSPM) with high dark count rate.

Solid-state photomultipliers (SSPMs) is a new type of semiconductor avalanche photodetectors operating in the Geigermode with negative feedback and allowing detection of individual photons. In recent years, SSPMs are increasingly widely used in nuclear physics, high-energy physics, medicine, biology, and other fields, replacing vacuum photomultipliers and avalanche photodiodes (APDs). The negative feedback in SSPMs provides a high multiplication factor (105–106) and an ultralow noise factor (1.01–1.05); however, noises of crosstalk and afterpulsing processes come to the fore in this case. In this communication, we present the results of experimental measurements of crosstalk processes in various SSPM samples and analyze the measurement techniques.

Solid State Photomultipliers (SSPM) are widely recognized as new generation of photodetectors competitive with APD and PMT in various applications. SSPM advantages are high gain and ultra-low excess noise factor of internal amplification resulting in ability to detect single photons, high photon detection efficiency, fast response and good time resolution. SSPM drawbacks are high dark count rate, high probability of cross-talk and afterpulsing, and low dynamic range.Many applications in Nuclear Science and Medical Imaging for photodetector with scintillator require good energy resolution, which is represented with respect to photodetector itself by pulse height resolution or so-called Photon Number Resolution (PNR).The purpose of this study is to express SSPM PNR in analytical form taking into account excess noise factor of crosstalk and afterpulsing as well as nonlinearity of photoresponse due to limited number of pixels and finite reset time. Normalization of PNR relatively to ideal detector characterizes the intrinsic detector performance in terms of total excess noise factor of photodetection or, inversely, in terms of detective quantum efficiency, which seems to be very powerful tool for SSPM optimization and evaluation of SSPM applicability and competitiveness.

Introduction. The detection of few-photon light pulses and single photons was and remains one of the most complex problems for photodetectors. In such widely used photodetector types as the avalanche photodiode (APD), vacuum photomultiplier (PM), and microchannel plate, this problem is solved due to the very high photoelectron multiplication factor, which allows separation of the single-electron signal from noise. The recently developed new type of photodetectors, i.e., the solid-state PM (SSPM), combines a high multiplication factor and an extremely low multiplication noise factor. These SSPM features make it possible not only to detect the mere fact of the signal transit, but also to resolve the number of photons in it [1–9]. The extremely accurate determination of the transit time of few-photon light pulses and single photons is an urgent problem in physics (the time-of-flight ring imaging Cherenkov detector), medicine (time-of-flight positron emission tomography), biology (fluorescence lifetime imaging microscopy, timecorrelated single photon spectroscopy, TCSPS), telecommunications, and many other fields. The time resolution of photodetectors is controlled by two key parameters: the photon detection efficiency (PDE) and transit time spread (TTS). The PDE is independent of the number of photons if the photodetector operates in the linear range, which is usually valid for few-photon signals, and the TTS decreases with an increase in the average number of photons in the pulse. The universal criterion of comparison of photodetectors by their time resolution is the TTS of the single photon detection signal; therefore, in what follows, we use the term TTS only in the context of single photon detection. The full width at half maximum (FWHM) of the peak of the transit time histogram or its root-mean-square (RMS) is typically used as a TTS numerical characteristic. In general, the parameters PDE and TTS are measured using different techniques and their results are not related to each other. To determine the PDE, the difference of photon counting frequencies (rates) under constant illumination of the photodetector and in dark is usually measured; in this case, the light intensity is selected so that to provide a sufficient signal-to-noise ratio in the absence of signal nonlinearity. In the measurements of the PDE in the SSPM, the problem of afterpulsing effects can arise, when actual primary output pulses cause secondary duplicated ones; therefore, the actual light counting rate should be correctly separated [10, 11]. To construct the TTS histogram, the difference between the time point of short light pulse generation (its duration is usually chosen much shorter than characteristic detection times and its shape can be considered as a delta-function) and the time point of output signal detection is measured. Since the number of photons in the pulse for ordinary lasers and light-emitting diodes is a random variable with

Precision measurement of weak light pulse arrival time is very important in various time-of-flight applications in high energy physics and medical imaging. Key characteristics of photodetectors responsible for time resolution in these applications are Photon Detection Efficiency (PDE) and single photon Transit Time Spread (TTS). Measurements of PDE and TTS are mostly carried out independently using rather different techniques and setups. We consider probability to detect single photon as defective cumulative distribution function (CDF) of single photon transit time and found analytical expressions how it may be reconstructed from multi-photon TTS histogram affected by dark counts. It allows us to propose a robust quantitative method of characterization of single photon detection process in form of instrumental response function (IRF), which provides both single photon TTS and PDE. The method seems to be especially relevant and useful for Solid State Photomultipliers (SSPM) with high dark count rate.

Operating principles of Solid State Photomultipliers are based on Geiger mode avalanche breakdown limited by strong negative feedback. This operating mode provides both high gain and ultra-low excess noise of avalanche multiplication resulting in ability to detect single photons. On the other hand high gain is accompanied with cross-talk and afterpulsing processes changing the probability distribution function of output signals and arising specific excess noise. There are many reports regarding its influence on signal distribution and noise, and we suggest that some analytical expressions would be useful. We therefore are presenting a simple model of probability distribution of output signals in the presence of cross-talk and afterpulsing (namely compound Poisson distribution). The model results allow us to calculate excess noise factor of cross-talk and afterpulsing as well as to find simple way to measure its probabilities.

Solid-state photomultipliers (SSPMs) are a new type of photodetectors based on avalanche breakdown of the semiconductor in the Geiger mode, limited by negative feedback. Under such conditions, the avalanche breakdown is characterized by high multiplication factors, 104–106, and low noise, which allows detection of single photons. However, in practice, each primary breakdown in the SSPM can be accompanied by secondary breakdowns due to cross-talk processes which change the probabilistic distribution of the signal and introduce excess noise. In this paper, the effect of cross-talk on signal and noise characteristics of SSPMs is considered based on the generalized Poisson distribution.

We describe a new type of a sensitive semiconductor photodetector that could be used in medical imaging applications. The photodetector, based on the mechanism of discrete amplification, has performance parameters comparable to, and for some applications exceeding, those of the vacuum photomultiplier tubes. High amplification gain achieved at very low levels of excess noise is accompanied by the fast speed and high dynamic range of the photodetector. Comparison of the technology with classic arrays of Geiger-mode APD arrays is also performed.

Recent advances in bio-optical methods for Medical Diagnostics, Optical Biopsy and Non-Invasive Imaging have the potential to prolong and improve the quality of life while significantly reducing medical costs for the diagnosis and tracking of diseases. Advances in the Genomics and pharmaceutical discovery using micro-array technology and High Throughput Screening permit to study thousands of compounds in short periods of time. This paper presents a new Si-based photonic sensors and sensor arrays with internal discrete amplification that offers the necessary qualities thus allowing development of a new generation of high gain, ultra low noise, universal analog and counting photodetectors for bio-optical sensing applications. The new photodetectors can operate in the linear detection mode with a gain-bandwidth product of up to 10(15)/sec and in the photon counting mode with count rates of up to 109 counts/sec. Detectors based on this amplification mechanism could have performance parameters superior to those of conventional avalanche photodiodes and photomultiplier tubes. For tested silicon photodetector prototypes, measured excess noise factor is as low as 1.02 at gains greater than 100,000.

The detection and identification of single molecules represent one of the ultimate goals of analytical chemistry. We have designed, developed and tested a new family of photodetectors with Internal Discrete Amplification (IDA) mechanism. These photodetectors can operate in linear (analog) detection mode with gain-bandwidth product up to 5.10(14) and one- or few-photon sensitivity, as well as in the photon counting mode with count rates up to 10(8) cps. Their key performance characteristics exceed those of photomultiplier tube (PMT) and avalanche photodiode (APD) devices. The measured parameters of the detectors are: gain >10(5), excess noise factor as low as 1.02, maximum count rate >10(8) counts/s, and rise/fall time < 300 ps. The new family of the photo detectors may become an ideal solution for the problems of ultrasensitive and single-molecule detection by fluorescence spectroscopy and other optical methods.

We have designed and developed a new family of photodetectors with Internal Discrete Amplification (IDA) mechanism They operate as solid state photomultiplier devices at room temperature and may be used in numerous applications where high bandwidth of the detector is necessary in combination with maximum sensitivity and low excess noise. The photodetectors can operate in linear detection mode with gain-bandwidth product up to 5.10(14) as well as in photon counting mode with count rates up to 10(8) counts/sec. The key performance characteristics exceed those of Photomultiplier Tube (PMT) and Avalanche Photodiode (APD) devices. The detectors have gain > 10(5), excess noise factor as low as 1.03, photoresponse rise/fall time < 300 ps, and timing resolution (jitter) < 200 ps. The combination of low excess noise at high gain and wide bandwidth, as well as scalability to large active areas, presents the main advantages of this technology over conventional photodetector solutions. Ultra low excess noise is one of the main features of the internal Discrete Amplification Detector (DAD), and in this paper its nature has been investigated more comprehensively. We investigated the behavior of the noise-factor and afterpulsing, and conclude that both have the same physical nature. Optical cross-talk between channels is shown to be responsible for the afterpulsing phenomenon, and, in turn, is the main source of excess noise. Thus, the noise characteristics of an DAD device and its timing resolution may be significantly improved as they are limited not by the discrete amplifier channel properties itself, but by the cross-talk, which strongly depends on the device design.

We demonstrate the feasibility of applying the emerging technology of internal discrete amplification to create an efficient, ultra low noise, universal analog and counting photodetector for LIDAR remote sensing. Photodetectors with internal discrete amplification can operate in the linear detection mode with a gain-bandwidth product of up to 1015 and in the photon counting mode with count rates of up to 109 counts/sec. Detectors based on this mechanism could have performance parameters superior to those of conventional avalanche photodiodes and photomultiplier tubes. For silicon photodetector prototypes, measured excess noise factor is as low as 1.02 at gains greater than 100,000. This gives the photodetectors and, consequently, the LIDAR systems new capabilities that could lead to important advances in LIDAR remote sensing.