InGaAs Single Photon Detector Research Articles

Design and characterization of microlens arrays for InGaAs single photon detectors

Design and characterization of microlens arrays for InGaAs single photon detectors

Research on linear array scanning lidar and photon signal processing technology based on InGaAs single-photon detector

Research on linear array scanning lidar and photon signal processing technology based on InGaAs single-photon detector

Remotely Gated InGaAs Single-Photon Detector at 1550 nm

Single-photon detectors (SPDs) are important devices in the development of quantum technologies, like quantum metrology, quantum computers and quantum communication. The simplest, cheapest and most commonly used SPD employs avalanche photodiode. After the photon absorption, a photocurrent is produced and it must be quenched before to damage the device. In the present work we show a new strategy for quenching the photocurrent of avalanche photodiodes remotely. Our scheme makes easier the synchronism between sender and receiver in a quantum communication setup. Some experimental results are presented.

1.06 μm wavelength based high accuracy satellite laser ranging and space debris detection

Classical satellite laser ranging (SLR) technology based on 532 nm wavelength usually adopts low energy laser to measure cooperative objects. However, for a very weak target, such as debris and lunar reflector arrays, laser ranging system should have much stronger detection capability than the laser ranging system for traditional application. A common way to improve system detection capability is to use high energy laser. With an additional frequency doubling crystal, it is more difficult to make a high energy laser based on 532 nm than that based on 1.06 μm, which restricts the improvement of system detection capability, and also gives rise to the short lifetime, poor system stability problems. Compared with 532 nm laser, the 1.06 μm laser has many advantages of high laser energy and power, high atmospheric transmissivity, and low background noise, thereby making it an ideal substitution for the traditional 532 nm SLR system. In this paper, we comparatively analyze the above-mentiond advantages of the 1.06 μm laser and other system’s key parameters such as detector efficiency and target reflection efficiency, calculate the echo photons one can obtain, and establish a 1.06 μm laser ranging system based on the existing 532 nm SLR at Shanghai Astronomical Observatory. Owing to the using of an InGaAs single photon detector, the system turns very compact, low cost, easy-to-be-installed and has almost no additional operation complexity than the 532 nm system. With this system, the high precision 1.06 μm laser ranging for cooperative objects based on InGaAs detector is carried out for the first time in China, and a ranging for space debris 1500 km away can also be realized. The ranging experiment shows with the same laser, SLR using 1.06 μm output reaches a detection efficiency of 7 times the detection efficiency the SLR using 532 nm output reaches, and the background noise only 1/5. This approves the advantages and feasibility of 1.06 μm system, and also shows its great potential application prospects in the high precision weak target laser detection in the day and night time. This paper provides a very easy operation, high compact and low cost method for the future high precision weak target laser ranging.

(Invited) Room-Temperature Single Photon Emission from Micrometer-Long Air-Suspended Carbon Nanotubes

Carbon nanotubes have a potential for becoming an ideal single-photon source as they have stable exciton states even at room temperature and their emission wavelengths cover the telecommunication bands. In recent years, single photon emission from carbon nanotubes has been achieved by creating localized states of excitons. In contrast to such an approach, here we utilize mobile excitons and show that single photons can be generated at room temperature in air-suspended carbon nanotubes with lengths of several microns [1]. We perform photoluminescence microscopy on as-grown air-suspended carbon nanotubes in order to determine their chirality and suspended length. Photon correlation measurements are performed on nanotube emission at room temperature using a Hanbury-Brown-Twiss setup with InGaAs single photon detectors. We observe antibunching with a clear excitation power dependence, where we obtain g (2)(0) value less than 0.5 at low excitation powers, indicating single photon generation. We show such g (2)(0) data for different chiralities and suspended lengths, and the effects of long exciton diffusion lengths and efficient exciton-exciton annihilation [2] on single photon generation processes are discussed. Work supported by JSPS (KAKENHI JP16H05962) and MEXT (Photon Frontier Network Program, Nanotechnology Platform). T.U. is supported by ALPS and JSPS Research Fellowship. [1] A. Ishii, T. Uda, Y. K. Kato, Phys. Rev. Applied, in press. Preprint available at arXiv:1707.05435 (2017).[2] A. Ishii, M. Yoshida, Y. K. Kato, Phys. Rev. B 91, 125427 (2015).

Free-running InGaAs single photon detector with 1 dark count per second at 10% efficiency

We present a free-running single photon detector for telecom wavelengths based on a negative feedback avalanche photodiode (NFAD). A dark count rate as low as 1 cps was obtained at a detection efficiency of 10%, with an afterpulse probability of 2.2% for 20 μs of deadtime. This was achieved by using an active hold-off circuit and cooling the NFAD with a free-piston stirling cooler down to temperatures of −110 °C. We integrated two detectors into a practical, 625 MHz clocked quantum key distribution system. Stable, real-time key distribution in the presence of 30 dB channel loss was possible, yielding a secret key rate of 350 bps.

A fast and versatile quantum key distribution system with hardware key distillation and wavelength multiplexing

We present a compactly integrated, 625 MHz clocked coherent one-way quantum key distribution system which continuously distributes secret keys over an optical fibre link. To support high secret key rates, we implemented a fast hardware key distillation engine which allows for key distillation rates up to 4 Mbps in real time. The system employs wavelength multiplexing in order to run over only a single optical fibre. Using fast gated InGaAs single photon detectors, we reliably distribute secret keys with a rate above 21 kbps over 25 km of optical fibre. We optimized the system considering a security analysis that respects finite-key-size effects, authentication costs and system errors for a security parameter of εQKD = 4 × 10−9.

FPGA-based gating and logic for multichannel single photon counting

We present results characterizing multichannel InGaAs single photon detectors utilizing gated passive quenching circuits (GPQC), self-differencing techniques, and field programmable gate array (FPGA)-based logic for both diode gating and coincidence counting. Utilizing FPGAs for the diode gating frontend and the logic counting backend has the advantage of low cost compared to custom built logic circuits and current off-the-shelf detector technology. Further, FPGA logic counters have been shown to work well in quantum key distribution (QKD) test beds. Our setup combines multiple independent detector channels in a reconfigurable manner via an FPGA backend and post processing in order to perform coincidence measurements between any two or more detector channels simultaneously. Using this method, states from a multi-photon polarization entangled source are detected and characterized via coincidence counting on the FPGA. Photons detection events are also processed by the quantum information toolkit for application testing (QITKAT).