Abstract
We propose and experimentally demonstrate a highly sensitive gas pressure sensor based on a near-balanced Mach-Zehnder interferometer (MZI) and constructed by hollow-core photonic bandgap fiber (HC-PBF) in this paper. The MZI is simply constructed by fusion splicing two HC-PBFs, which are of slightly different lengths, between two 3-dB couplers. The two output ends of each coupler are approximately equal in length, to ensure that the optical path variations of the MZI only result from the differences in the lengths between the two HC-PBFs. To apply the MZI for gas pressure sensing, a femtosecond laser is employed to drill a micro-channel in one of the two HC-PBF arms. The experiment result shows that the proposed MZI based gas pressure sensor achieves an ultrahigh sensitivity, up to 2.39 nm/kPa, which is two orders of magnitude higher than that of the previously reported MZI-based gas pressure sensors. Additionally, the effects resulting from the absolute length and relative length of the two HC-PBFs on gas pressure sensing performance are also investigated experimentally and theoretically, respectively. The ultra-high sensitivity and ease of fabrication make this device suitable for gas pressure sensing in the field of industrial and environmental safety monitoring.
Highlights
Gas pressure sensors are one of the most widely used sensors for industrial and environmental monitoring
long-period fiber gratings (LPFGs) inscribed in single-mode fiber (SMF) [1], photonic crystal fiber [2,3,4], polymer micro-structured fiber [5], boron co-doped optical fiber [6] and fiber Bragg gratings (FBGs) inscribed in single-mode fiber [7,8], side-hole fiber [9], air-hole micro-structured fiber [10,11], have been used as gas pressure sensors, respectively
We propose a highly sensitive Mach-Zehnder interferometer (MZI) based gas pressure sensor, which is formed by fusion splicing two hollow-core photonic bandgap fibers (HC-PBFs) with different lengths between the equal-length output ports of two 3 dB couplers, respectively
Summary
Gas pressure sensors are one of the most widely used sensors for industrial and environmental monitoring. The fiber interferometers based gas pressure sensors, by contrast, are attractive due to their high sensitivity. The fiber in-line MZIs based on an inner air-cavity with open micro-channel [25] and twin-core fiber [26] have been demonstrated for gas pressure sensing with the sensitivity of 8.239 pm/kPa and −9.6 pm/kPa, respectively. We propose a highly sensitive MZI based gas pressure sensor, which is formed by fusion splicing two hollow-core photonic bandgap fibers (HC-PBFs) with different lengths between the equal-length output ports of two 3 dB couplers, respectively. The effects resulting from the absolute length and relative length of the two HC-PBFs on gas pressure sensing performance are investigated experimentally and theoretically, respectively. The high sensitivity and ease of fabrication make this device suitable for gas pressure sensing in the field of industrial and environmental safety monitoring
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