Historical Perspectives, State of Art and Research Trends of SPAD Arrays and Their Applications (Part II: SPAD Arrays)

Abstract

The ability to detect single photons is becoming an enabling key capability in an increasing number of fields. Indeed, its scope is not limited to applications that specifically rely on single photons, such as quantum imaging, but extends to applications where a low signal is overwhelmed by background light, such as laser ranging, or in which faint excitation light is required not to damage the sample or harm the patient. In the last decades, SPADs gained popularity with respect to other single-photon detectors thanks to their small size, possibility to be integrated in complementary metal-oxide semiconductor processes, room temperature operability, low power supply and, above all, the possibility to be fast gated (to time filter the incoming signal) and to precisely timestamp the detected photons. The development of large digital arrays that integrates the detectors and circuits has allowed the implementation of complex functionality on-chip, tailoring the detectors to suit the need of specific applications. This review proposes a complete overview of silicon SPADs characteristics and applications. In the previous Part I, starting with the working principle, simulation models and required frontend, the paper moves to the most common parameters adopted in literature for characterizing SPAD performance and describes single pixels applications and their performance. In this Part II, the focus is posed on the development of SPAD arrays, presenting some of the most notable examples found in literature. The actual exploitation of these designs in real applications (e.g., automotive, bioimaging and radiation detectors) is then discussed.

A Roadmap for Gigabit to Terabit Optical Wireless Communications Receivers

“…Fortunately, since these SiPMs were manufactured the ability to stack two chips has been developed [ 31 ]. If one of these chips is used to create an array of APDs and the other to create a matching array of ancillary circuits, then this technology avoids the trade-off between circuit complexity and fill factor.…”

“…In addition, this technology means that the two chips can be made by using the manufacturing processes best suited to their function. These advantages mean that stacked systems, often known as SPAD arrays, have been created in which one of these chips contains an array of APDs and the other chip contains a matching array of quenching circuits as well as relatively sophisticated digital circuits [ 31 ].…”

Fast Wide‐Field Quantum Sensor Based on Solid‐State Spins Integrated with a SPAD Array

“…In particular, SPADs are well suited to the realization of large‐format arrays for imaging applications since they allow single‐photon sensitivity together with high frame rates and spatial resolution. [ 13 ] CMOS Active Pixel Sensors (APS) are high‐speed devices, but they do not perform internal amplification, thus suffering from low sensitivity. Electron‐multiplying charged coupled devices (EMCCD) and intensified CCDs (ICCD), although having high sensitivity and possibly millions of pixels, are bulkier, slower, and more expensive than SPAD arrays.…”

High-efficiency fill factor recovery using refractive microlens arrays imprinted on 0.5–256 kpixel front-side illuminated SPAD imagers

“…The overall sensitivity of frontside-illuminated (FSI) single-photon avalanche diode (SPAD) arrays [1], [2] is often limited by fill factor. Low fill factor can especially affect photon-starved imaging applications [3] , while microlenses placed in close proximity to pixels can recover some of this loss.…”