A 4.5 ps precision TCSPC system: design principles and characterization

With the recent advancements in single-photon detectors, very low-jitter timing systems are required to fully exploit their performance in real applications. In this article, we present the design principles and experimental characterization of a single-channel time-correlated single-photon counting (TCSPC) system, that achieves a jitter down to 4.5 ps FWHM, a peak-to-peak differential nonlinearity of 1.5 % LSB and a count rate of 12 Mcps over a nanoseconds full-scale range. These results have been attained by minimizing the different jitter contributions that are introduced at various levels in the whole timing chain, still without trading them off with the other performance parameters. To the best of our knowledge, this work represents the state-of-the-art performance in case of a full-scale range as large as 12.5 ns

Custom silicon technology for SPAD-arrays with red-enhanced sensitivity and low timing jitter

Single-photon detection is an invaluable tool for many applications ranging from basic research to consumer electronics. In this respect, the Single Photon Avalanche Diode (SPAD) plays a key role in enabling a broad diffusion of these techniques thanks to its remarkable performance, room-temperature operation, and scalability. In this paper we present a silicon technology that allows the fabrication of SPAD-arrays with an unprecedented combination of low timing jitter (95 ps FWHM) and high detection efficiency at red and near infrared wavelengths (peak of 70% at 650 nm, 45% at 800 nm). We discuss the device structure, the fabrication process, and we present a thorough experimental characterization of the fabricated detectors. We think that these long-awaited results can pave the way to new exciting developments in many fields, ranging from quantum optics to single molecule spectroscop

Two-photon interference using background-free quantum frequency conversion of single photons from a semiconductor quantum dot

We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs quantum dot (QD) at 980 nm with a 1550 nm pump laser in a periodically-poled lithium niobate (PPLN) waveguide to generate photons at 600 nm with a signal-to-background ratio exceeding 100:1. Photon correlation and two-photon interference measurements confirm that both the single photon character and wavepacket interference of individual QD states are preserved during frequency conversion. Finally, we convert two spectrally separate QD transitions to the same wavelength in a single PPLN waveguide and show that the resulting field exhibits non-classical two-photon interference.Comment: Supercedes arXiv:1205.221

Readout Architectures for High Efficiency in Time-Correlated Single Photon Counting Experiments—Analysis and Review

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

3.3 Gigahertz Clocked Quantum Key Distribution System

A fibre-based quantum key distribution system operating up to a clock frequency of 3.3GHz is presented. The system demonstrates significantly increased key exchange rate potential and operates at a wavelength of 850nm.Comment: Presented at ECOC 05, Glasgow, UK, (September 2005

A 1.9 ps-rms Precision Time-to-Amplitude Converter With 782 fs LSB and 0.79%-rms DNL

Measuring a time interval in the nanoseconds range has opened the way to 3-D imaging, where additional information as distance of objects light detection and ranging (LiDAR) or lifetime decay fluorescence-lifetime imaging (FLIM) is added to spatial coordinates. One of the key elements of these systems is the time measurement circuit, which encodes a time interval into digital words. Nowadays, most demanding applications, especially in the biological field, require time-conversion circuits with a challenging combination of performance, including sub-ps resolution, ps precision, several ns of measurement range, linearity better than few percent of the bin width (especially when complex lifetime data caused by multiple factors have to be retrieved), and operating rates in the order of tens of Mcps. In this article, we present a time-to-amplitude converter (TAC) implemented in a SiGe 350 nm process featuring a resolution of 782 fs, a minimum timing jitter as low as 1.9 ps-rms, a DNL down to 0.79% LSB-rms, and conversion rate as high as 12.3 Mcps. With an area occupation of 0.2 mm2 [without PADs and digital-to-analog converter (DAC)], a FSR up to 100 ns, and a power dissipation of 70 mW, we developed a circuit suitable to be the core element of a densely integrated, faster and high-performance system

Recent advances and future perspectives of single-photon avalanche diodes for quantum photonics applications

Photonic quantum technologies promise a revolution of the world of information processing, from simulation and computing to communication and sensing, thanks to the many advantages of exploiting single photons as quantum information carriers. In this scenario, single-photon detectors play a key role. On the one hand, superconducting nanowire single-photon detectors (SNSPDs) are able to provide remarkable performance on a broad spectral range, but their applicability is often limited by the need of cryogenic operating temperatures. On the other hand, single-photon avalanche diodes (SPADs) overcome the intrinsic limitations of SNSPDs by providing a valid alternative at room temperature or slightly below. In this paper, we review the fundamental principles of the SPAD operation and we provide a thorough discussion of the recent progress made in this field, comparing the performance of these devices with the requirements of the quantum photonics applications. In the end, we conclude with our vision of the future by summarizing prospects and unbeaten paths that can open new perspectives in the field of photonic quantum information processing

Note: Fully integrated active quenching circuit achieving 100 MHz count rate with custom technology single photon avalanche diodes

The minimization of Single Photon Avalanche Diodes (SPADs) dead time is a key factor to speed up photon counting and timing measurements. We present a fully integrated Active Quenching Circuit (AQC) able to provide a count rate as high as 100 MHz with custom technology SPAD detectors. The AQC can also operate the new red enhanced SPAD and provide the timing information with a timing jitter Full Width at Half Maximum (FWHM) as low as 160 ps

High-efficiency integrated readout circuit for single photon avalanche diode arrays in fluorescence lifetime imaging

In recent years, lifetime measurements by means of the Time Correlated Single Photon Counting (TCSPC) technique have led to a significant breakthrough in medical and biological fields. Unfortunately, the many advantages of TCSPC-based approaches come along with the major drawback of a relatively long acquisition time. The exploitation of multiple channels in parallel could in principle mitigate this issue, and at the same time it opens the way to a multi-parameter analysis of the optical signals, e.g., as a function of wavelength or spatial coordinates. The TCSPC multichannel solutions proposed so far, though, suffer from a tradeoff between number of channels and performance, and the overall measurement speed has not been increased according to the number of channels, thus reducing the advantages of having a multichannel system. In this paper, we present a novel readout architecture for bi-dimensional, high-density Single Photon Avalanche Diode (SPAD) arrays, specifically designed to maximize the throughput of the whole system and able to guarantee an efficient use of resources. The core of the system is a routing logic that can provide a dynamic connection between a large number of SPAD detectors and a much lower number of high-performance acquisition channels. A key feature of our smart router is its ability to guarantee high efficiency under any operating condition