title: Ultra-sensitive all-fibre photothermal spectroscopy with large dynamic range.
abstract: Photothermal interferometry is an ultra-sensitive spectroscopic means for trace chemical detection in gas- and liquid-phase materials. Previous photothermal interferometry systems used free-space optics and have limitations in efficiency of light-matter interaction, size and optical alignment, and integration into photonic circuits. Here we exploit photothermal-induced phase change in a gas-filled hollow-core photonic bandgap fibre, and demonstrate an all-fibre acetylene gas sensor with a noise equivalent concentration of 2 p.p.b. (2.3 × 10(-9) cm(-1) in absorption coefficient) and an unprecedented dynamic range of nearly six orders of magnitude. The realization of photothermal interferometry with low-cost near infrared semiconductor lasers and fibre-based technology allows a class of optical sensors with compact size, ultra sensitivity and selectivity, applicability to harsh environment, and capability for remote and multiplexed multi-point detection and distributed sensing.
authors: Department of Electrical Engineering and Photonics Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.|Photonic Sensors Research Center, The Hong Kong Polytechnic University Shenzhen Research Institute, No. 18 Yuexing 1st Road, Nanshan District, Shenzhen 518057, China.
authors: Wei
authors: W
authors: Jin
authors: Department of Electrical Engineering and Photonics Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.|Photonic Sensors Research Center, The Hong Kong Polytechnic University Shenzhen Research Institute, No. 18 Yuexing 1st Road, Nanshan District, Shenzhen 518057, China.
authors: Yingchun
authors: Y
authors: Cao
authors: Department of Electrical Engineering and Photonics Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.|Photonic Sensors Research Center, The Hong Kong Polytechnic University Shenzhen Research Institute, No. 18 Yuexing 1st Road, Nanshan District, Shenzhen 518057, China.
authors: Fan
authors: F
authors: Yang
authors: Department of Electrical Engineering and Photonics Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.|Photonic Sensors Research Center, The Hong Kong Polytechnic University Shenzhen Research Institute, No. 18 Yuexing 1st Road, Nanshan District, Shenzhen 518057, China.
authors: Hoi Lut
authors: HL
authors: Ho