Development and characterization of an 8x8 SPAD-array module for gigacount per second applications

Abstract

In recent years the development of Single-Photon Avalanche Diodes (SPADs) had a big impact on single-photon counting applications requiring high-performance detectors in terms of Dark Count Rate (DCR), Photon Detection Efficiency (PDE), afterpulsing probability, etc. Among these, it is possible to find applications in single-molecule fluorescence spectroscopy that suffer from long-time measurements. In these cases SPAD arrays can be a solution in order to shorten the measurement time, thanks to the high grade of parallelism they can provide. Moreover, applications in other fields (e.g. astronomy) demand for large-area single-photon detectors, able also to handle very high count rates. For these reasons we developed a new single-photon detection module, featuring an 8 × 8 SPAD array. Thanks to a dedicated silicon technology, the performance of the detector have been finely optimized, reaching a 49% detection efficiency at 550 nm, as well as low dark counts (2 kcount/s maximum all over the array). This module can be used in two different modes: the first is a multi-spot configuration, allowing the acquisition of 64 optical signals at the same time and considerably reducing the time needed for a measurement. The second operation mode instead exploits all the pixels in a combined mode, allowing the detection of a 64-times higher maximum photon rate (up to 2 Gcount/s). In addition, this configuration provides also an extended dynamic range and allows to attain photon number resolving capabilities. Dark counts, detection efficiency, linearity, afterpulsing and crosstalk probability have been characterized at different operating conditions.

High-throughput, multi-parametric, and correlative fluorescence lifetime imaging

“…When using point-excitation, data can can collected with SPAD arrays in three primary modes. All of these modes allow fast, high-throughput imaging via massively parallelised acquisition: Scanning a single-spot at high excitation power and distributing the emission across all array units [ 29 ] Scanning of multiple excitation spots, and mapping emission spots onto the array [ 24 , 31 ] Using prisms before the array to disperse the emission beam for spectral-FLIM capabilities [ 27 ] …”

“…Scanning a single-spot at high excitation power and distributing the emission across all array units [ 29 ]…”

“…This parallelisation reduces acquisition times by a linear factor which is proportional to the number of SPAD units in the array. Photons from all SPAD pixels can be pooled for a single high-speed measurement with an extended dynamic range [ 29 ]. This means that a larger range of signal intensities can be covered, from low background to very bright pixels in the same image, by distributing the signal into many detectors and raising the total upper limit of detectable photons.…”

High-speed dual color fluorescence lifetime endomicroscopy for highly-multiplexed pulmonary diagnostic applications and detection of labeled bacteria

“…Crucially this parallelization increases the maximum detectable number of photons per unit time enabling more efficient use of the fluorescently excited photons with a high counting rate. It has previously been demonstrated [23], that the use of a 8×8 SPAD array, as a single pixel detector, showed a factor 64 increase in photon rate.…”

Dependence of Functional Parameters of Sine-Gated InGaAs/InP Single-Photon Avalanche Diodes on the Gating Parameters

“…Single photon detector (SPD) is a device, that is sensitive to single photons with a specific wavelength. SPD's have many applications, such as quantum key distribution (QKD) [1], 3D imaging systems (LIDAR) [2], optical time domain reflectometry (OTDR) [3], fluorescence microscopy [4], biomarker tomography [5], astronomical telescopy [6] etc. SPD's structure is not universal, it's designed for a specific application and operating parameters and is based on various physical principals.…”