Time-Resolved Diffuse Optical Spectroscopy up to 1700 nm by Means of a Time-Gated InGaAs/InP Single-Photon Avalanche Diode

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InGaAs/InP SPAD photon-counting module with auto-calibrated gate-width generation and remote control

We present a photon-counting module based on InGaAs/InP SPAD (Single-Photon Avalanche Diode) for detecting single photons up to 1.7 μm. The module exploits a novel architecture for generating and calibrating the gate width, along with other functions (such as module supervision, counting and processing of detected photons, etc.). The gate width, i.e. the time interval when the SPAD is ON, is user-programmable in the range from 500 ps to 1.5 μs, by means of two different delay generation methods implemented with an FPGA (Field-Programmable Gate Array). In order to compensate chip-to-chip delay variation, an auto-calibration circuit picks out a combination of delays in order to match at best the selected gate width. The InGaAs/InP module accepts asynchronous and aperiodic signals and introduces very low timing jitter. Moreover the photon counting module provides other new features like a microprocessor for system supervision, a touch-screen for local user interface, and an Ethernet link for smart remote control. Thanks to the fullyprogrammable and configurable architecture, the overall instrument provides high system flexibility and can easily match all requirements set by many different applications requiring single photon-level sensitivity in the near infrared with very low photon timing jitter

Advanced single photon counting instrumentation for SPADs

In order to acquire low-level optical signals with picosecond resolution, Single-Photon Avalanche Diodes (SPADs) are exploited thanks to their extreme performance. For many demanding applications, there is a growing need to operate such detectors with advanced instrumentation, specifically designed for efficiently exploiting the best performance in terms of sensitivity, timing resolution, fast-gating capabilities, etc. To this purpose we designed, tested and employed an ultra-fast pulse generator, a fast gated-counter and a wide-band delayer. The pulse generator is designed for gating SPADs with fast transition times (less than 100 ps), when it is needed to avoid unwanted photons that either precede or follow the useful signal. The gated counter acquires photons in well-defined time windows, programmable from 100 ps up to 10 ns. Finally, a wide-band delayer provides programmable delays, ranging from 25 ps up to 6.4 ns in steps of 25 ps. Such a delayer can be used to synchronize signals in many different experimental setups

Single-photon counting with InGaAs/InP SPAD

We present a full-programmable single-photon counting module for the near-infrared wavelength range based on InGaAs/InP Single-Photon Avalanche Diode. It has high detection efficiency (> 25%), low timing jitter (<90 ps) and 133 MHz gate repetition rate

A compact Time-to-Digital Converter (TDC) Module with 10 ps resolution and less than 1.5% LSB DNL

We present a low-power Time-to-Digital Converter (TDC) module that provides 10 ps timing resolution, DNL better than 1.5% LSB and 160 ns dynamic range within a compact 6 cm x 6 cm x 8 cm housing. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an userfriendly software interface. The module is suitable for a wide variety of applications such as: FLIM, FRET, TOF ranging measurements, TOF PET, DOT, OTDR, quantum optics, etc

Telecommunications-band heralded single photons from a silicon nanophotonic chip

We demonstrate room temperature heralded single photon generation in a CMOS-compatible silicon nanophotonic device. The strong modal confinement and slow group velocity provided by a coupled resonator optical waveguide produced a large four-wave-mixing nonlinearity coefficient gamma_eff =4100 W-1 m-1 at telecommunications wavelengths. Spontaneous four-wave-mixing using a degenerate pump beam at 1549.6 nm created photon pairs at 1529.5 nm and 1570.5 nm with a coincidence-to-accidental ratio exceeding 20. A photon correlation measurement of the signal (1529.5 nm) photons heralded by the detection of the idler (1570.5 nm) photons showed antibunching with g(2)(0)=0.19 +/- 0.03. The demonstration of a single photon source within a silicon platform holds promise for future integrated quantum photonic circuits

Heralded single photons from a silicon nanophotonic chip

A highly nonlinear (γ≈3700/W·m) silicon coupled-resonator-optical-waveguide generated heralded single photons (g(2) (0) ≤ 0.19 ±0.03) and widely-spaced photon pairs with coincidences-to-accidentals ratio &gt;10 (cw) and &gt;23 (pulsed), and outperformed a 54× longer silicon nanophotonic waveguide