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http://dx.doi.org/10.1364/ol.18.001110 | DOI Listing |
We investigate a novel distributed Brillouin optical time domain reflectometer (BOTDR) using standard telecommunication fibers based on single-photon avalanche diodes (SPADs) in gated mode, ν -BOTDR, with a range of 120 km and 10 m spatial resolution. We experimentally demonstrate the ability to perform a distributed temperature measurement, by detecting a hot spot at 100 km. Instead of using a frequency scan like conventional BOTDR, we use a frequency discriminator based on the slope of a fiber Bragg grating (FBG) to convert the count rate of the SPAD into a frequency shift.
View Article and Find Full Text PDFWe demonstrate an approach to measure average temperature changes in deployed optical fiber networks using Optical Time Domain Reflectometry, OTDR, at the single photon level. In this article we derive a model relating the change in temperature of an optical fiber to the change in time of flight of reflected photons in the fiber in the range -50 → 400 °C. A setup is constructed to validate this model utilizing a pulsed 1550 nm laser and a Superconducing Nanowire Single Photon Detector, SNSPD.
View Article and Find Full Text PDFMicromachines (Basel)
February 2023
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
Free-running InGaAs/InP single-photon avalanche photodiodes (SPADs) typically operate in the active-quenching mode, facing the problems of long dead time and large timing jitter. In this paper, we demonstrate a 1-GHz gated InGaAs/InP SPAD with the sinusoidal gating signals asynchronous to the incident pulsed laser, enabling free-running single-photon detection. The photon-induced avalanche signals are quenched within 1 ns, efficiently reducing the SPAD's dead time and achieving a count rate of up to 500 Mcount/s.
View Article and Find Full Text PDFTo our knowledge, we are the first to measure the absolute value of the backscattering coefficient of a standard 1 mm core-diameter, multimode (MM) step-index (SI) polymethylmethacrylate (PMMA) polymer optical fiber (POF) for the spectral range of 450 nm to 700 nm. Our optical time domain reflectometer (OTDR) setup consists of a femtosecond supercontinuum laser with an acousto-optical filter as a tunable light source with short pulses and a time-correlated single-photon counting system as a receiver with a high dynamic range. The backscattering coefficient is calculated from the ratio between the energy within the fiber end reflex and the distributed backscattering level.
View Article and Find Full Text PDFWe present the characterization of high extinction ratio () square optical pulses using a photon counting technique, as other techniques only offer a limited range of measurement up to 60 dB. High- pulses are generated by applying a square pulse modulation on sinusoidally modulated optical signals, then inducing self-phase modulation (SPM) using the nonlinear Kerr effect and extracting an SPM-generated sideband. We measured a 10 ns Kerr-generated optical pulse exhibiting a 120.
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