Silicon Single-photon Avalanche Photodiodes Research Articles

Calibration and comparison of detection efficiency for free-space single-photon avalanche diodes at 850 nm.

A detection efficiency measurement system for free-space single-photon detectors has been established at the National Research Council (NRC) Canada. This measurement apparatus incorporates an 850 nm fiber laser source and utilizes a double-attenuation and substitution calibration technique. Detection efficiency calibrations of silicon single-photon avalanche photodiodes (SPADs) at incident photon rates in the range of 1.0×105 photon counts per second (Cts/s) (36 fW) to 2.1×106Cts/s (734 fW) are SI-traceable through the substitution configuration with a silicon transfer standard detector, calibrated directly using the NRC absolute cryogenic radiometer. The measurement approach taken by the NRC was compared with the SPAD calibration technique implemented at the National Institute of Standards and Technology (NIST) in the United States. The count-rate-dependent detection efficiency of a silicon SPAD was measured at NIST and compared with results from the same SPAD measured at NRC within the range of incident photon rates from 1×105Cts/s to 5×105Cts/s. Comparison of the calibration results shows agreement between the two laboratories within the combined measurement uncertainties.

Design and implementation of silicon single-photon avalanche photodiode modeling tool for QKD systems

Single-photon detection concept is the most crucial factor that determines the performance of quantum key distribution (QKD) systems. In this paper, a simulator with time domain visualizers and configurable parameters using continuous time simulation approach is presented for modeling and investigating the performance of single-photon detectors operating in Gieger mode at the wavelength of 830 nm. The widely used C30921S silicon avalanche photodiode was modeled in terms of avalanche pulse, the effect of experiment conditions such as excess voltage, temperature and average photon number on the photon detection efficiency, dark count rate and afterpulse probability. This work shows a general repeatable modeling process for significant performance evaluation. The most remarkable result emerged from the simulated data generated and detected by commercial devices is that the modeling process provides guidance for single-photon detectors design and characterization. The validation and testing results of the single-photon avalanche detectors (SPAD) simulator showed acceptable results with the theoretical and experimental results reported in related references and the device's data sheets.

High-fidelity, low-latency polarization quantum state transmissions over a hollow-core conjoined-tube fiber at around 800 nm

Hollow-core fiber (HCF) promises to unify air-borne light propagation and non-line-of-sight transmission, thus holding great potential for versatile photonics-based quantum information applications. The early version of HCF based on photonic-bandgap guidance has not proven itself a reliable quantum channel because of the poor modal purity in both spatial and polarization domains, as well as significant difficulty in fabrication when the wavelength shifts to the visible region. In this work, based on the polarization degree of freedom, we demonstrate high-fidelity ( ∼ 0.98 ) single-photon transmission and distribution of entangled photons over a 36.4 m hollow-core conjoined-tube fiber (CTF) by using commercial silicon single-photon avalanche photodiodes. Our CTF realizes the combined merits of low loss, high spatial modal purity, low polarization degradation, and low chromatic dispersion. We also demonstrate single-photon low-latency ( ∼ 99.96 % speed of light in vacuum) transmission, paving the way for extensive uses of HCF links in versatile photonics-based quantum information processing.

Design of wafer-bonded structures for near room temperature Geiger-mode operation of germanium on silicon single-photon avalanche photodiode.

We investigate the effect of temperature on the single-photon properties of four germanium/silicon (Ge/Si) single-photon avalanche photodiodes (SPADs), which are fabricated by Ge-on-Si direct epitaxial growth, Ge-on-Si two-step epitaxial growth, Ge/Si direct wafer bonding, and Si/Si hydrophobic bonding, respectively. It is found that the wafer-bonded Ge/Si SPAD exhibits extremely low dark current and dark count rate (DCR) compared with the epitaxial ones at 250 and 300K. This implies that the wafer-bonding technique is a possible candidate for the fabrication of Ge/Si SPAD, which can be operated at near room temperature. Additionally, due to the low DCR and high operation temperature, the wafer-bonded Ge/Si SPAD shows extremely high pulse repetition rate (∼28 MHz in theory for DCR=108 Hz). That is, the wafer-bonded Ge/Si SPAD can be used in a high-speed field. Finally, the effect of voltage pulse width, number of photons per pulse, and hold-off time on the performance of the wafer-bonded Ge/Si SPAD at different temperatures is also clarified.

Generation of high quality random numbers via an all-silicon-based approach

A quantum random number generator (QRNG) based on a silicon nanocrystals (Si-NCs) light emitting device (LED) coupled with a silicon single photon avalanche photodiode (Si-SPAD) is presented. A simple setup is used for the generation of random bits. The modeled approach assures a negligible bias on datasets of ∼100 Mbits length. The raw data pass all the statistical tests in the National Institute of Standards and Technology (NIST) suite without any post-processing operations. The bit-rate of 0.6 Mbps is achieved. The information-theoretically provable randomness extractor of Toeplitz-hashing function is applied to longer datasets (∼1 Gbits) to extract the randomness, to minimize the bias, and consequently pass all the NIST tests. Stabilizing the temperature, resetting the applied current to the LED, or a feedback system can also be used as parameter control solutions to generate good quality, long datasets of random numbers suitable for cryptographic applications.

Characterization of a Commercially Available Large Area, High Detection Efficiency Single-Photon Avalanche Diode

We characterize a new commercial, back-illuminated reach-through silicon single-photon avalanche photo diode (SPAD) SAP500 (Laser Components. Inc.), operated in Geiger-mode for purpose of photon counting. We show that for this sensor a significant interplay exists between dark counts, detection efficiency, afterpulsing, excess voltage and operating temperature, sometimes requiring a careful optimization tailored for a specific application. We find that a large flat plateau of sensitive area of about 0.5 mm in diameter, a peak quantum efficiency of 73% at 560 nm and timing precision down to 150 ps FWHM are the main distinguishing characteristics of this SPAD.

Cascaded frequency upconversion for high-speed single-photon detection at 1550 nm

We present a device for two-stage frequency upconversion of single-photon-level signals in the 1.55 μm telecom band to the green spectral region with low excess noise, suitable for detection by low-timing-jitter silicon single-photon avalanche photodiodes (APDs). We achieve a net conversion efficiency of 87% and a system timing jitter below 70 ps FWHM, dominated by the jitter of the APD. Modifications of our device are suitable for downconversion of single photons from visible-wavelength quantum emitters into the telecom band.

Single-photon avalanche photodiodes with integrated quenching resistor

In this paper we present the results of the first electrical and optical characterization performed on STMicroelectronics new photosensor technology based on silicon single-photon avalanche photodiodes (SPAD). On the prospective of the design and the manufacturing of large-area silicon photomultipliers to be used as photodetectors for nuclear medicine imaging applications, we have modified our previous SPAD technology by means of the integration of a high-value quenching resistor to the photodiode. Moreover, an appropriate antireflective coating layer and the reduction of the quasi-neutral region thickness above the thin junction depletion layer have been introduced in the process flow of the device to enhance its spectral response in blue and near ultraviolet wavelength ranges. High gain, low leakage currents, low dark noise, very good quantum detection efficiency in blue–near UV ranges and a good linearity of the photodiode response to the incident luminous flux are the main characterization results.

Single photon avalanche photodiodes arrays

In this paper, we present the results regarding the electrical and optical characterization of bidimensional arrays of silicon single photon avalanche photodiodes (SPAD). Low average dark count rates and crosstalk probability, good timing jitter and high quantum detection efficiency in the visible range have been measured over 5 × 5 SPAD arrays with 40 μm single pixel active area diameter. Moreover, a very good uniformity of these parameters has been found over the single pixels. These good electro-optical performances make our photodiodes attractive for the fabrication of arrays with a larger number of SPAD. In view of the design of a dense array to be used as a silicon photomultiplier (SiPM) for medical diagnostic tools, 5 × 5 SPAD arrays have been also tested in the photon-resolving mode. Charge spectra show that the arrays, in this configuration, allow to resolve several photoelectron peaks with a good single photoelectron resolution.

Experimental investigation of the performance limits for first telecommunications-window quantum cryptography systems

Quantum cryptography offers the unique possibility of certifiably secure key distribution between remote locations, practical systems require efficient, low noise, single photon avalanche photodiodes (SPADs) to achieve this goal. This letter reports experimental results from a polarization-encoded system utilizing a state-of-the-art silicon SPAD. The system is used to investigate the performance limits of quantum cryptography systems operating in the first optical fiber communication window at wavelengths around 0.8 /spl mu/m. The results demonstrate the potential for secure quantum key distribution at Mb/spl middot/s/sup 1/ rates over fiber LANs also carrying conventional high-speed (Gb/spl middot/s/sup 1/) data channels at a wavelength of 1.3 /spl mu/m.