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In this letter, we present the timing performance of an optimized red-enhanced single-photon avalanche diode (RE-SPAD) manufactured with a fully custom fabrication process. The detector has been characterized with an external CMOS front end circuit able to read out the RE-SPAD avalanche current and provide the timing information with state-of-the-art jitter. In particular, the careful minimization of the RE-SPAD capacitive parasitics, along with the transimpedance architecture and the gigahertz bandwidth of the front end circuit, allowed the achievement of a timing jitter as low as 83 ps full width at half maximum that increases only up to 103 ps for a detection threshold as high as 600 mV. This feature makes it possible to implement high-threshold detection systems insensitive to the electrical disturbances coming from other SPADs integrated in the same chip, demonstrating that the extension of this work to multichannel systems is feasible. [ABSTRACT FROM AUTHOR]

In recent years, time-correlated single photon counting (TCSPC) has become the technique of choice in many life science analyses, where fast and faint luminous signals are recorded with picosecond accuracy. Nevertheless, the maximum operating frequency of a single TCSPC acquisition channel limits the measurement speed, especially when scanning point systems are exploited. In order to increase the speed of TCSPC experiments, many multichannel systems based on single photon avalanche diode arrays have been proposed in the literature, which integrate thousands of pixels on the same chip. Unfortunately, the huge number of data generated by this kind of system can easily bring to the saturation of the transfer bandwidth to the external processing unit. For this reason, several different readout architectures have been proposed in the literature, attempting to exploit at best the limited bandwidth under TCSPC operating conditions. In this paper, some typical readout approaches, namely clock-driven and event-driven readouts, are discussed and compared, along with a recently-introduced router-based algorithm that is specifically designed to obtain maximum bandwidth exploitation under any condition. Quantitative comparisons are performed starting from imager response of the systems, which is the rate of recorded events in the case of uniform illumination of the detector array. [ABSTRACT FROM PUBLISHER]

In recent years, single-photon timing techniques have been employed in a steadily increasing number of applications. Most of these applications require high detector performance in terms of noise, photon detection efficiency, time resolution, and number of pixels operating in parallel. The detectors best fitting these requirements are single-photon avalanche diode (SPAD) arrays built in custom technology, although the systems based on such detectors are limited to a few pixels. In this paper, we present a novel read-out circuit, developed in a 0.18- $\mu $ m high voltage-CMOS technology, for the detection of the SPAD avalanche current: the designed circuit is based on a 2.2-GHz bandwidth integrated transimpedance amplifier, followed by a low-pass filter, to reduce crosstalk, and by an integrated comparator. The pick-up circuit has a total power dissipation of 1.1 mW, occupies an overall area of 15500 \mu $ \mathrm{m}^{2} and shows a time resolution down to 48 ps and a negligible crosstalk between two different pixels. All these features can open the way to the development of large SPAD arrays, characterized by a performance comparable with that of the single-pixel structures. Moreover, the good agreement between the simulated and the measured resolution (with a 14% maximum error) makes the future improvement of the evaluated performance possible. [ABSTRACT FROM AUTHOR]

In free-space single-photon quantum key distribution (QKD), the error rate due to daytime background photons can be reduced with strong temporal filtering. In this case, the improvement in performance is determined by the receiver's ability to resolve signal-photon arrival times. We use fast clock recovery and commercially available single-photon detectors with timing resolution enhanced by additional electronic circuitry to implement temporal gating down to 50 ps in a free-space QKD system. The single-photon channel operates at 850 nm, and the improved timing resolution enables transmission rates of 1.25 GHz. We observe daytime quantum bit error rates of 0.04, which is less than one-third of the ungated error rate. We present the design and performance of the system and demonstrate its benefit to free-space QKD. [ABSTRACT FROM PUBLISHER]

We report the first resonant-cavity-enhanced single photon avalanche diode (RCE SPAD) fabricated on a reflecting silicon-on-insulator (SOI) substrate. The substrate incorporates a two period distributed Bragg reflector fabricated using a commercially available double SOI process. The RCE SPAD detectors have peak photon detection efficiencies ranging from 42% at 780 nm to 34% at 850 nm and an excellent photon timing resolution of 35 ps full width at half maximum. Despite the higher defectivity of double SOI substrates compared to standard silicon substrates, RCE SPADs with 20 µm diameter exhibit a fairly low dark count rate (DCR) of 3500 cs-1 at room temperature and a yield of 80%. A DCR less than 50 cs-1 can be attained with these detectors by reducing the temperature down to -15°C, while keeping the total afterpulsing probability below 9% with a dead-time of 80 ns. [ABSTRACT FROM AUTHOR]

In life science, optical techniques for the characterization of biological processes are well established and widely used. In most of them, to obtain the best performances, detectors with single-photon detection capability are required. Moreover, the growing demand for this type of information is pushing the technology towards a parallelization of the analysis. These requirements make it very challenging to develop new detection heads, because state-of-the-art detectors, such as photomultiplier tubes (PMTs) and charged coupled devices (CCDs), have some drawbacks. For example, in fluorescence correlation spectroscopy (FCS) fluorescence fluctuations must be monitored on a short time scale because typical time constants range from hundreds of nanoseconds to milliseconds. In this case, developing parallel modules for this application is very challenging. In fact, PMTs are bulky and they cannot be integrated, while the use of imaging detectors, such as CCDs and electron multiplying CCDs, is strongly limited by the read time that determines the minimum correlation time detectable by FCS analysis. We present here a multichannel photon counting module that exploits a monolithic array of single-photon avalanche diodes (SPADs). The detector array consists of eight 50 µm diameter SPADs featuring low dark counting rate and high photon detection efficiency (50% at 550 nm); inter-pixel crosstalk probability is as low as 2 × 10-3. The use of highly integrated active quenching circuits makes it possible to design a very compact read-out circuit, yet providing eight fully independent counting channels operating at high count rate (up to 30 million counts per second). Parallel-mode operation, high count rate and low-cost make this module a potential breakthrough for a widespread diffusion of FCS analysis. [ABSTRACT FROM AUTHOR]

Design and fabrication of single photon avalanche detector (SPAD) in planar technology is reported. Device design and critical issues in the technology are discussed. Experimental test procedures are described for dark-counting rate, afterpulsing probability, photon timing resolution, and quantum detection efficiency. Low-noise detectors are obtained, with dark counting rates down to 10 c/s for devices with 10 µm diameter, down to 1 kc/s for 50 µm diameter. The technology is suitable for monolithic integration of SPAD detectors and associated circuits. [ABSTRACT FROM AUTHOR]

Presents a study which manufactured high-sensitivity solid-state detectors designed for measurements in laser scanning microscopy. Discussion on laser scanning microscopy; Description of photodetectors structures; Results and discussion; Conclusions.