Dual-Core Fiber-Based Interferometer for Detection of Gas Refractive Index

Abstract

We demonstrate a dual-core fiber-based Mach–Zehnder interferometer that could be used for precise detection of variations in refractive indices of gaseous samples. The fiber used here have a solid germanium-doped silica core and an air core that allows gases to flow through. Coherent laser beams are coupled to the two cores, respectively, and thus excite guiding modes thereby. Interferogram would be produced as the light transmitted from the dual cores interferes. Variations in refractive index of the hollow core lead to variations in phase difference between the modes in the two cores, thus shifting the interference fringes. The fringe shifts can be then interrogated by a photodiode together with a narrow slit in front. The resolution of the sensor was found to be ~1 × 10−8 RIU, that is comparable to the highest resolution obtained by other fiber sensors reported in previous literatures. Other advantages of our sensor include very low cost, high sensitivity, straightforward sensing mechanism, and ease of fabrication.

THz sensor based on dual-core PCF with defect core in detecting adulteration of olive oil

“…Siddik et al has designed a dual-core PCF sensor for temperature measurement with two round pores of different diameters with a sensitivity of 2.25 nm/°C (Siddik et al 2020). Chen et al proposed a MZI based on dual-core fiber, in which two cores are designed as an eccentric germaniumdoped silica core and an air core allowing gas to pass through, and the sensor has a resolution of up to 1 × 10 −8 RIU (Chen et al 2020). Chu S et al designed a six-fold dual-core D-shaped PCF biosensor embedded with silver nanowires based on surface plasmon resonance, which can detect analytes with different refractive indices, with the highest sensitivity of 4000 nm / RIU (Chu et al 2021).…”