Simultaneous measurement of refractive index and temperature using multimode microfiber-based dual Mach–Zehnder interferometer

Abstract

A multimode microfiber (MMMF)-based dual Mach-Zehnder interferometer (MZI) is proposed and demonstrated for simultaneous measurement of refractive index (RI) and temperature. By inserting a section of MMMF supporting a few modes in the sensing arm of the MZI setup, an inline interference between the fundamental mode and the high-order mode of MMMF, as well as the interference between the high-order mode of MMMF and the reference arm, i.e., the dual MZI, is realized. Due to different interference mechanisms, the former interferometer achieves RI sensitivity of 2576.584 nm/RIU and temperature sensitivity of -0.193 nm/°C, while the latter one achieves RI sensitivity of 1001.864 nm/RIU and temperature sensitivity of 0.239 nm/°C, demonstrating the ability to attain highly accurate multiparameter measurements.

Self-temperature-compensative refractometer based on singlemode–multimode–singlemode fiber structure

“…In Ref. [16], a so-called dual Mach-Zehnder interferometer was proposed, which has an SMS arm and an additional arm that has different sensitivities to surrounding RI and temperature. The two parameters can be demodulated from a sensitivity matrix.…”

Refractive index and temperature-sensing characteristics of a cladding-etched thin core fiber interferometer

“…22,23 Usually, the MZI, which is fabricated by mechanical pressing and heat stretching, is formed by changing the geometry of the fiber. The manufacturing cost is low, but the manufacturing process is complex, and because of the severe deformation of the optical fiber, the insertion loss will increase and the sensitivity will decrease.…”

Multi-Components Interferometer Based on Partially Filled Dual-Core Photonic Crystal Fiber for Temperature and Strain Sensing

“…Multi-parameter sensors usually consist of one or more sensing elements that have different responses to all measurands, which could be achieved by cascading several fiber devices [16], [17] or utilizing different optical modes in a single fiber structure [18]. Many techniques have been proposed to achieve multiparameter sensing, such as dual-pass interferometers for multiparameter sensing [19], [20], fiber gratings combined with PCFs [21], [22], multimode-fiber-based interferometers [23]- [25], and selectively infiltrated PCFs with wavelength-or mode-dependent sensitivities [26]- [28]. However, dual-pass interferometers require extra optical delay line and couplers and multimode fiber based interferometers exhibit relatively low sensitivities.…”