TY - JOUR
T1 - Phase-Modulation-Amplifying Hollow-Core Fiber Photothermal Interferometry for Ultrasensitive Gas Sensing
AU - Bao, Haihong
AU - Jin, Wei
AU - Hong, Yingzhen
AU - Ho, Hoi Lut
AU - Gao, Shoufei
AU - Wang Yingying, null
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China under Grant 61827820, in part by the Hong Kong SAR Government GRF under Grant PolyU 152206/17E, in part by the Local Innovative and Research Teams Project of Guangdong Pear River Talents Program under Grant 2019BT02X105, and in part by the Hong Kong Polytechnic University under Grant W151, YW4C.
Publisher Copyright:
© 1983-2012 IEEE.
PY - 2022/1/1
Y1 - 2022/1/1
N2 - Photothermal interferometry (PTI) with hollow core fibers (HCFs) have enabled highly sensitive spectroscopic gas sensors in an all-fiber format. Here we report remarkable improvement in the limit of detection of HCF-PTI, in terms of noise equivalent concentration (NEC), by exploiting the optical-phase-modulation amplifying (OPMA) effect of an HCF resonating cavity. By locking the wavelength of a 1550 nm probe laser to the resonance of a 10-cm-long HCF Fabry-Pérot cavity with a finesse of ∼700, OPMA of more than two orders of magnitude is achieved, which enables ultra-sensitive gas detection with large dynamic range. With 1654 nm, 1532 nm, and 761 nm pump lasers, we demonstrate detection of methane, acetylene, and oxygen with noise-equivalent-concentration of 15 parts-per-trillion (ppt), 2.7 ppt, and 0.56 parts-per-million (ppm), respectively. Further improvement in NEC is possible by use of a higher finesse cavity with a longer length of HCF. Extension of the technique to other gases, other types of phase or dispersion modulation-based sensors, and other optical resonating cavities is straightforward.
AB - Photothermal interferometry (PTI) with hollow core fibers (HCFs) have enabled highly sensitive spectroscopic gas sensors in an all-fiber format. Here we report remarkable improvement in the limit of detection of HCF-PTI, in terms of noise equivalent concentration (NEC), by exploiting the optical-phase-modulation amplifying (OPMA) effect of an HCF resonating cavity. By locking the wavelength of a 1550 nm probe laser to the resonance of a 10-cm-long HCF Fabry-Pérot cavity with a finesse of ∼700, OPMA of more than two orders of magnitude is achieved, which enables ultra-sensitive gas detection with large dynamic range. With 1654 nm, 1532 nm, and 761 nm pump lasers, we demonstrate detection of methane, acetylene, and oxygen with noise-equivalent-concentration of 15 parts-per-trillion (ppt), 2.7 ppt, and 0.56 parts-per-million (ppm), respectively. Further improvement in NEC is possible by use of a higher finesse cavity with a longer length of HCF. Extension of the technique to other gases, other types of phase or dispersion modulation-based sensors, and other optical resonating cavities is straightforward.
KW - Fiber optics
KW - hollow-core fiber
KW - optical cavity
KW - optical fiber sensors
KW - photothermal effects
UR - http://www.scopus.com/inward/record.url?scp=85117847509&partnerID=8YFLogxK
U2 - 10.1109/JLT.2021.3120559
DO - 10.1109/JLT.2021.3120559
M3 - Journal article
SN - 0733-8724
VL - 40
SP - 313
EP - 322
JO - Journal of Lightwave Technology
JF - Journal of Lightwave Technology
IS - 1
M1 - 9576604
ER -