Abstract
A systematic comparison of fiber-based gas pressure sensors using different types of hollow-core photonic crystal fibers (PCFs) is conducted. The sensor was fabricated by splicing a segment of hollow-core silica capillary between a single mode fiber (SMF) and a hollow-core PCF. A Fabry-Perot (FP) cavity configuration is thus formed with the capillary tube as the sensing cavity, while the PCF acts as gas passage to the external environment. External pressure change would lead to the variation in the refractive index of air in the sensing cavity, resulting in a wavelength shift of the interference dips. The pressure sensitivity is measured to be around 4 nm/MPa, with a high linearity of 99.7% or above, regardless of the type of the PCFs we used as gas inlet. Among the four different PCFs, the large-mode-area (LMA) PCF shows the highest fringe contrast in the reflection spectrum. Modal analysis reveals that this is due to the high reflectivity caused by the solid core of LMA-PCF. Our experimental results also indicate that the length of the sensing cavity, as well as the offset fusion splice will influence the fringe contrast. The sensor has potential application in gas pressure sensing for advantages of high sensitivity, compact size and ease of fabrication.
Highlights
In recent years, photonic crystal fibers (PCF) have attracted much attention due to its unique microstructure with low transmission loss, characteristics of high birefringence, and highly flexible design
Our analysis show that the high contrast ratio is due to the high reflectivity from the second interface, where light is reflected at the solid core of LMA-PCF
Sensor Principle and Fabrication ncore − nair ncore + nair neff − nair 2 neff + nair where ncore and nair represent for the refractive index of silica core and air, respectively. neff denote for the effective refractive index of the PCF with air-hole, which is determined by the microstructure of the fiber
Summary
Photonic crystal fibers (PCF) have attracted much attention due to its unique microstructure with low transmission loss, characteristics of high birefringence, and highly flexible design. The first challenge is that if both the sensing cavity and gas inlet are PCFs in a cascaded FP cavity configuration, it is difficult to splice two PCFs together without causing high loss [17], [18] Another challenge is that the contrast ratio of the interference spectrum is small due to the low reflectivity of the second interface between the two PCFs [14]. We compare four fiber-based gas pressure sensors with Fabry-Perot cavity configuration utilizing different types of hollow-core PCFs. A silica capillary tube with 75 μm air hole in diameter forms the sensing cavity while four different types of PCFs serve as the gas inlet. We experimentally confirmed that two other parameters: the length of the sensing cavity and the offset for fusion splice the PCFs, can affect the contrast ratio of the spectrum
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
