High-sensitivity gas pressure sensor based on hollow-core photonic bandgap fiber Mach-Zehnder interferometer

Abstract

We propose and experimentally demonstrate a highly sensitive gas pressure sensor based on a near-balanced Mach-Zehnder interferometer (MZI) and constructed by hollowcore 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.

Realization of Low Confinement Loss Acetylene Gas Sensor by Using Hollow-core Photonic Bandgap Fiber 

“…In order to estimate the relative sensitivity of the proposed gas sensor, different values for the hollow-core radius were considered to obtain the most appropriate value. So, we calculated the relative sensitivity in a desired radial range, by accumulation the optical power located in the hollow-core, and dividing it by the total optical power carried by the fundamental mode [9], [28].…”

“…Since HC-PBF -based gas sensors that work with the optical power absorption mechanism are highly dependent on light intensity, their relative sensitivity is also expected to be highly dependent on changes in light intensity. Thus, eliminating the mode interference will increase the relative sensitivity [13], [28]. The first step is to pass light through a single-mode fiber before being directed into the photonic bandgap fiber, so mode mismatch at the junction of the two mentioned fibers can be suppressed.…”

Temperature-Independent Gas Pressure Sensor with High Birefringence Photonic Crystal Fiber-Based Reflective Lyot Filter

“…Hence, the research on the measurement of gas pressure has become a focus of attention in recent years, and a variety of gas pressure sensors have been proposed and developed by researchers in succession. With the characteristics of light weight, high temperature resistance, and anti-electromagnetic interference, fiber-based gas pressure sensors [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] have stood out from the numerous gas pressure sensors and are well suited for gas pressure measurement in various industrial equipment.…”

“…Nowadays, according to the working principle, the typical fiber-based gas pressure sensors can be mainly divided into two categories: Optical fiber grating-based gas pressure sensor [1,2,3] and optical fiber interferometer-based gas pressure sensor [4,5,6,7,8,9,10,11,12,13,14,15,16]. For the optical fiber grating-based gas pressure sensor, its sensor head is typically constituted by a fiber grating, such as the long-period grating (LPG) inscribed by periodically inflating photonic crystal fiber (PCF) [1] or hollow-core photonic bandgap fiber (HC-PBF) [2], and the fiber Bragg grating (FBG) written in a bare fiber [3].…”

“…Compared with the optical fiber grating-based gas pressure sensor, the optical fiber interferometer-based gas pressure sensor is more widely used due to its inherent characteristics of simple structure and high sensitivity. So far, the optical fiber interferometers used in the gas pressure sensors mainly contain Mach–Zehnder interferometers (MZI) [4,5,6,7] and Fabry–Perot interferometers (FPI) [8,9,10,11,12,13,14,15,16]. The MZIs constituted by twin-core fiber [4], inner air-cavity in single mode fiber (SMF) [5], dual side-hole fiber (DSHF) [6], and HC-PBF [7] have been applied in the field of gas pressure detection, and yet for the above MZI-based gas pressure sensors [4,5,6,7], it is essential to employ a femtosecond laser to drill micro-channel on the interferometer structure, which sharply increases the cost.…”