- 标题
- 摘要
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- 实验方案
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37ps-Precision Time-Resolving Active Quenching Circuit for High-Performance Single Photon Avalanche Diodes
摘要： Time-resolved imaging by means of single-photon avalanche diodes (SPADs) has achieved widespread interest in recent years, especially since technological progress has opened the way to the development of multichannel time-correlated single-photon counting (TCSPC) acquisition systems. Unfortunately, currently available TCSPC imagers feature relatively low performance with respect to state-of-the-art single-channel systems. A real breakthrough in this field would be the exploitation of large arrays of high-performance SPAD detectors developed by means of dedicated fabrication processes, usually referred to as custom technology. Custom-technology SPADs require external electronics potentially leading to interconnection issues for densely integrated arrays. In this paper, we present a new fully integrated front-end circuit able to provide both quenching/reset and timing functionalities while requiring a single connection toward the SPAD. This is the first fully integrated circuit reported in literature that can provide both the timing information about the photon time of arrival with a jitter as low as 37 ps and apply high-voltage pulses up to 50 V in order to meet the requirements of several detectors, including the new red-enhanced SPAD. Combining these two capabilities in a single circuit strongly reduces the complexity of the connection between an array of custom-technology SPADs and the relative external front end, thus paving the way for the exploitation of high-performance SPADs in TCSPC imaging systems.
关键词： Active Quenching Circuit,AQC,timing,time-resolved,SPAD,Single Photon Avalanche Diode,SPAD front end
更新于2025-09-23 15:23:52
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A robust and versatile platform for image scanning microscopy enabling super-resolution FLIM
摘要： Image scanning microscopy (ISM) can improve the effective spatial resolution of confocal microscopy to its theoretical limit. However, current implementations are not robust or versatile, and are incompatible with fluorescence lifetime imaging (FLIM). We describe an implementation of ISM based on a single-photon detector array that enables super-resolution FLIM and improves multicolor, live-cell and in-depth imaging, thereby paving the way for a massive transition from confocal microscopy to ISM.
关键词： super-resolution,SPAD array,fluorescence lifetime imaging,confocal microscopy,image scanning microscopy
更新于2025-09-23 15:23:52
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Compact Real-Time Inter-Frame Histogram Builder for 15Bits High-Speed ToF-Imagers based on Single-Photon Detection
摘要： Time-of-flight image sensors based on single-photon detection, i.e. SPADs, require some filtering of pixel readings. Accurate depth measurements are only possible if the jitter of the detector is mitigated. Moreover, the time stamp needs to be effectively separated from uncorrelated noise such as dark counts and background illumination. A powerful tool for this is building a histogram of a number of pixel readings. Future generation of ToF imagers are seeking to increase spatial and temporal resolution along with the dynamic range and frame rate. Under these circumstances, storing the complete histogram for every pixel becomes practically impossible. Considering that most of the information contained by the histogram represents noise, we propose a highly efficient method to store just the relevant data required for ToF computation. This method makes use of the shifted inter-frame histogram (SifH). It requires a memory as low as 128 times smaller than storing the complete histogram if the pixel values are coded on up to 15 bits. Moreover, a fixed 28 words memory is enough to process histograms containing up to 215 bins. In exchange, the overall frame rate only decreases to one half. The hardware implementation of this algorithm is presented. Its remarkable robustness for a low SNR of the ToF estimation is demonstrated by Matlab simulations and FPGA implementation using input data from a SPAD camera prototype.
关键词： shifted inter-frame histogram (SifH),single-photon avalanche-diode (SPAD),real-time time-of-flight (ToF) estimation,ToF image sensor
更新于2025-09-23 15:22:29
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Background Light Rejection in SPAD-Based LiDAR Sensors by Adaptive Photon Coincidence Detection
摘要： Light detection and ranging (LiDAR) systems based on silicon single-photon avalanche diodes (SPAD) offer several advantages, like the fabrication of system-on-chips with a co-integrated detector and dedicated electronics, as well as low cost and high durability due to well-established CMOS technology. On the other hand, silicon-based detectors suffer from high background light in outdoor applications, like advanced driver assistance systems or autonomous driving, due to the limited wavelength range in the infrared spectrum. In this paper we present a novel method based on the adaptive adjustment of photon coincidence detection to suppress the background light and simultaneously improve the dynamic range. A major disadvantage of fixed parameter coincidence detection is the increased dynamic range of the resulting event rate, allowing good measurement performance only at a specific target reflectance. To overcome this limitation we have implemented adaptive photon coincidence detection. In this technique the parameters of the photon coincidence detection are adjusted to the actual measured background light intensity, giving a reduction of the event rate dynamic range and allowing the perception of high dynamic scenes. We present a 192 × 2 pixel CMOS SPAD-based LiDAR sensor utilizing this technique and accompanying outdoor measurements showing the capability of it. In this sensor adaptive photon coincidence detection improves the dynamic range of the measureable target reflectance by over 40 dB.
关键词： system-on-chip (SoC),single-photon avalanche diode (SPAD),CMOS,light detection and ranging (LiDAR),time-of-flight (TOF),background light rejection
更新于2025-09-23 15:22:29
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Distance-Resolving Raman Radar Based on a Time-Correlated CMOS Single-Photon Avalanche Diode Line Sensor
摘要： Remote Raman spectroscopy is widely used to detect minerals, explosives and air pollution, for example. One of its main problems, however, is background radiation that is caused by ambient light and sample fluorescence. We present here, to the best of our knowledge, the first time a distance-resolving Raman radar device that is based on an adjustable, time-correlated complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode line sensor which can measure the location of the target sample simultaneously with the normal stand-off spectrometer operation and suppress the background radiation dramatically by means of sub-nanosecond time gating. A distance resolution of 3.75 cm could be verified simultaneously during normal spectrometer operation and Raman spectra of titanium dioxide were distinguished by this system at distances of 250 cm and 100 cm with illumination intensities of the background of 250 lux and 7600 lux, respectively. In addition, the major Raman peaks of olive oil, which has a fluorescence-to-Raman signal ratio of 33 and a fluorescence lifetime of 2.5 ns, were distinguished at a distance of 30 cm with a 250 lux background illumination intensity. We believe that this kind of time-correlated CMOS single-photon avalanche diode sensor could pave the way for new compact distance-resolving Raman radars for application where distance information within a range of several metres is needed at the same time as a Raman spectrum.
关键词： time-correlated single photon counting (TCSPC),remote Raman spectroscopy,CMOS single-photon avalanche diode (SPAD),time interval measurement,distance-resolving Raman radar,stand-off Raman spectrometer
更新于2025-09-23 15:21:21
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Silicon Photomultipliers and SPAD imagers in biophotonics: Advances and perspectives
摘要： Photonics is essential in life science research and the continuous development of methods offers researchers tools of unprecedented sensitivity. Sensors are key to the exploitation of the most advanced biophotonic techniques with highly demanding specifications in terms of single photon sensitivity, time resolution, miniaturization real-time processing and data throughput. Silicon photomultipliers and Single Photon Avalanche Diode (SPAD) imagers represent the state-of-the-art in photon detection with single photon sensitivity, photon number resolving capability and the possibility to integrate on chip advanced functionalities. As a consequence, they can be the platform for the next generation biophotonic instruments and methods. This paper summarises the main biophotonic techniques and reports exemplary applications of Silicon Photomultipliers and SPAD imagers for fluorescence, chemiluminescence, time correlated single photon counting and imaging. Achievements and current limitations are addressed, pointing as well to the most recent technology advances and highlighting the possible pathways for the near future.
关键词： SPAD imagers,Biophotonic techniques,Silicon Photomultipliers
更新于2025-09-23 15:21:21
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An 80 x 25 Pixel CMOS Single-Photon Sensor With Flexible On-Chip Time Gating of 40 Subarrays for Solid-State 3-D Range Imaging
摘要： A CMOS solid-state 3-D range imager that uses short (～110 ps) laser pulses and a novel flexible time gating scheme for a single-photon avalanche diode (SPAD) array is presented. The array is divided into 40 subarrays for which a narrow (<0.8 ns) time gating position can be set and scanned independently. The imager can be set to measure multiple regions of interest by means of the flexible time gating of the subarrays. The time gating for each of the subarrays is selected separately with an on-chip delay-locked loop (DLL) block that has 240 outputs and a delay grid of ～100 ps. The prototype has 80 × 25 pixels overall with 10 × 5 pixel subarrays. The fill factor of the sensor area is 32%. A 3-D range image is demonstrated at ～10 frames/s with centimeter-level precision in the case of passive targets within a range of ～4 m and a field of view of 18° × 28°, requiring an average active illumination power of only 0.1 mW.
关键词： time gating,3-D imager,SPAD array,single-photon avalanche diode (SPAD),time-of-flight (TOF)
更新于2025-09-19 17:15:36
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A CMOS SPAD Imager with Collision Detection and 128 Dynamically Reallocating TDCs for Single-Photon Counting and 3D Time-of-Flight Imaging
摘要： Per-pixel time-to-digital converter (TDC) architectures have been exploited by single-photon avalanche diode (SPAD) sensors to achieve high photon throughput, but at the expense of fill factor, pixel pitch and readout efficiency. In contrast, TDC sharing architecture usually features high fill factor at small pixel pitch and energy efficient event-driven readout. While the photon throughput is not necessarily lower than that of per-pixel TDC architectures, since the throughput is not only decided by the TDC number but also the readout bandwidth. In this paper, a SPAD sensor with 32 × 32 pixels fabricated with a 180 nm CMOS image sensor technology is presented, where dynamically reallocating TDCs were implemented to achieve the same photon throughput as that of per-pixel TDCs. Each 4 TDCs are shared by 32 pixels via a collision detection bus, which enables a fill factor of 28% with a pixel pitch of 28.5 μm. The TDCs were characterized, obtaining the peak-to-peak differential and integral non-linearity of ?0.07/+0.08 LSB and ?0.38/+0.75 LSB, respectively. The sensor was demonstrated in a scanning light-detection-and-ranging (LiDAR) system equipped with an ultra-low power laser, achieving depth imaging up to 10 m at 6 frames/s with a resolution of 64 × 64 with 50 lux background light.
关键词： image sensor,light detection and ranging,time-of-flight,SPAD,time-to-digital converter,LiDAR,single-photon avalanche diode,collision detection bus,dynamic reallocation
更新于2025-09-19 17:15:36
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Toward Long-Distance Underwater Wireless Optical Communication Based on A High-Sensitivity Single Photon Avalanche Diode
摘要： In this study, we built a single photon avalanche diode (SPAD) receiver based underwater wireless optical communication (UWOC) system. The bit error rate (BER) and signal-to-noise ratio (SNR) performance of UWOC with different distances and data transmission rates were obtained. Based on the water attenuation coefficient of 0.12 m-1, a series of neutral density (ND) filters were exploited to attenuate the light output power from the blue laser diode (LD) to simulate the long distance UWOC. The maximum estimated distances of 144 m and 117 m with corresponding BERs of 1.89 × 10-3 and 5.31 × 10-4 at data transmission rates of 500 bps and 2 Mbps were acquired in UWOC system using on-off keying (OOK) modulation scheme, respectively. Furthermore, we compared the differences between free-space and underwater channels, and a divergence angle of ~1.02 mrad was measured experimentally at a distance of 50 m in the free space. The long UWOC distances obtained in this study partly benefit from high sensitivity SPAD, the small laser divergence angle and low light attenuation. This study provides an approach to achieve long distance UWOC using SPAD.
关键词： laser,on-off keying,single photon avalanche diode (SPAD),Underwater wireless optical communication (UWOC)
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Development of SPAD Based on Thermoelectrically Controlled Silicon Carbide Avalanche Photodiode
摘要： Single photon detectors, which are capable of ultra-sensitive detection in a low light level, have been widely used in a variety of applications such as remote sensing, biochemical science, and quantum information science. In particular, the rapid development of quantum information science has greatly improved the development of single photon detectors because it played a key role in achieving successful results in quantum key distribution and quantum communication. The single photon avalanche photodiodes (SPADs) are most conventional devices to detect photons because the APDs, the core elements of SPADs, are known to be advantageous to achieve cheap production and robust structure. In recent years, as the demand for ultraviolet light detection has increased, there have been actively reported on the development of APD detectors based on silicon carbide (SiC), which has a high gain only in the deep ultraviolet wavelength band. Here we report on the performance evaluation of lab-assembled SPAD based on SiC-APD.
关键词： ultraviolet light detection,quantum information science,Single photon detectors,SPAD,SiC-APD
更新于2025-09-16 10:30:52