Yuechuan Lin
Hong Kong Polytechnic University
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Publication
Featured researches published by Yuechuan Lin.
Optics Letters | 2016
Fan Yang; Yanzhen Tan; Wei Jin; Yuechuan Lin; Yun Qi; Hoi Lut Ho
A highly sensitive, compact, and low-cost trace gas sensor based on photothermal effect in a hollow-core fiber Fabry-Perot interferometer (FPI) is described. The Fabry-Perot sensor is fabricated by splicing a piece of hollow-core photonic bandgap fiber (HC-PBF) to single-mode fiber pigtails at both ends. The absorption of a pump beam in the hollow core results in phase modulation of probe beam, which is detected by the FPI. Experiments with a 2 cm long HC-PBF with femtosecond laser drilled side-holes demonstrated a response time of less than 19 s and noise equivalent concentration (NEC) of 440 parts-per-billion (ppb) using a 1 s lock-in time constant, and the NEC goes down to 117 ppb (2.7×10-7 in absorbance) by using 77 s averaging time.
Scientific Reports | 2016
Yuechuan Lin; Wei Jin; Fan Yang; Jun Ma; Chao Wang; Hoi Lut Ho; Yang Liu
Gas detection with hollow-core photonic bandgap fibre (HC-PBF) and pulsed photothermal (PT) interferometry spectroscopy are studied theoretically and experimentally. A theoretical model is developed and used to compute the gas-absorption-induced temperature and phase modulation in a HC-PBF filled with low-concentration of C2H2 in nitrogen. The PT phase modulation dynamics for different pulse duration, peak power and energy of pump beam are numerically modelled, which are supported by the experimental results obtained around the P(9) absorption line of C2H2 at 1530.371 nm. Thermal conduction is identified as the main process responsible for the phase modulation dynamics. For a constant peak pump power level, the phase modulation is found to increase with pulse duration up to ~1.2 μs, while it increases with decreasing pulse duration for a constant pulse energy. It is theoretically possible to achieve ppb level detection of C2H2 with ~1 m length HC-PBF and a pump beam with ~10 ns pulse duration and ~100 nJ pulse energy.
Journal of Lightwave Technology | 2017
Fan Yang; Wei Jin; Yuechuan Lin; Chao Wang; Hoi Lut; Yanzhen Tan
Recent progress in gas detection with hollow-core microstructured optical fibers (HC-MOFs) and direct absorption/photothermal interferometry spectroscopy are reported. For direct-absorption sensors, the issue of mode interference noise is addressed and techniques to minimize such a noise are experimentally demonstrated. Large-scale drilling of hundreds of low-loss micro-channels along a single HC-MOF is performed, and reduction of diffusion-limited response time from hours to ∼40 s is demonstrated with a 2.3-m-long HC-MOF. For photothermal inteferometry sensors, novel detection configurations based on respectively a Sagnac interferometer and an in-fiber modal interferometer are experimentally demonstrated. The Sagnac configuration avoids the need for complex servo-control for interferometer stabilization while the in-fiber configuration simplifies the detection, reducing the size and cost of the sensor system. Sub ppm gas detection can be achieved easily with photothermal interferometry HC-MOF sensors but is difficult to achieve for direct-absorption sensors with the current commercial HC-MOFs.
Optics Express | 2017
Yuechuan Lin; Fei Liu; Xiangge He; Wei Jin; Min Zhang; Fan Yang; Hoi Lut Ho; Yanzhen Tan; Lijuan Gu
We report the first distributed optical fibre trace-gas detection system based on photothermal interferometry (PTI) in a hollow-core photonic bandgap fibre (HC-PBF). Absorption of a modulated pump propagating in the gas-filled HC-PBF generates distributed phase modulation along the fibre, which is detected by a dual-pulse heterodyne phase-sensitive optical time-domain reflectometry (OTDR) system. Quasi-distributed sensing experiment with two 28-meter-long HC-PBF sensing sections connected by single-mode transmission fibres demonstrated a limit of detection (LOD) of ∼10 ppb acetylene with a pump power level of 55 mW and an effective noise bandwidth (ENBW) of 0.01 Hz, corresponding to a normalized detection limit of 5.5ppb⋅W/Hz. Distributed sensing experiment over a 200-meter-long sensing cable made of serially connected HC-PBFs demonstrated a LOD of ∼ 5 ppm with 62.5 mW peak pump power and 11.8 Hz ENBW, or a normalized detection limit of 312ppb⋅W/Hz. The spatial resolution of the current distributed detection system is limited to ∼ 30 m, but it is possible to reduce down to 1 meter or smaller by optimizing the phase detection system.
Asia Pacific Optical Sensors Conference (2016), paper W3A.2 | 2016
Yuechuan Lin; Wei Jin; Fan Yang; Yang Liu
The dynamics of photothermal phase modulation in a gas-filled hollow-core photonic bandgap fiber pumped by a pulsed laser is investigated. The magnitude of phase modulation for different parameters of the pump pulses is studied numerically and experimentally.
optical fiber sensors conference | 2017
Yuechuan Lin; Wei Jin; Fan Yang; Hoi Lut Ho
Pulsed photothermal interferometry (PTI) gas sensor with hollow-core photonic bandgap fibre (HC-PBF) is demonstrated with a Sagnac interferometer-based phase detection system. Under the condition of constant peak pump power, the optimal pulse duration is found to be > 1.2 μβ for detecting low-concentration of trace gases in nitrogen, limited by thermal conduction of gases within the hollow-core. Preliminary experiments with a 0.62-m-long HC-PBF gas cell, low peak power (∼ 20.2 mW) and a boxcar averager with 10k average times demonstrated a detection limit of 3.3 p.p.m acetylene. Detection limit down to ppb or lower is expected with high peak power pump pulses.
Workshop on Specialty Optical Fibers and Their Applications (2015), paper WT4A.34 | 2015
Yuechuan Lin; Wei Jin; Jun Ma; Chao Wang; Fan Yang; Hoi Lut Ho
Stable operation of graphene-diaphragm based fiber-tip photoacoustic gas sensor is achieved by use of a modified Sagnac interferometer with a 3x3 coupler. A detection limit of 1.5 ppm of C2H2 balanced with 𝑁2 is demonstrated and the system stability is <0.4 dB over 6 hours.
Archive | 2017
Yp Miao; Wei Jin; Fan Yang; Yuechuan Lin; Yanzhen Tan; Hoi Lut Ho
Optics Letters | 2018
Yan Zhao; Wei Jin; Yuechuan Lin; Fan Yang; Hoi Lut Ho
conference on lasers and electro optics | 2016
Yuechuan Lin; Wei Jin; Fan Yang; Chao Wang