Compact three segmented multimode fibre modal interferometer for high sensitivity refractive-index measurement

Abstract

We experimentally demonstrate a new compact surrounding refractive-index sensor using a MMF-CSF-MMF (MCM) structure. The evanescent waves in the coreless silica fibre (CSF) region can directly interact with the surrounding medium. Due to its distinctive resonant spectral feature, the MCM sensor showed a high sensitivity of 4.37 × 10 −4 for a refractive index range of 1.30 to 1.44, suggesting that the proposed device may be suitable for a wide range of biomedical and chemical sensor applications.

Fiber-optic refractive-index sensors based on transmissive and reflective thin-core fiber modal interferometers

“…The sensor structure based on coreless silica fiber (CSF) reported by Jung et al [16] can be regarded as an extreme case of the TCFMI. The existence of fiber core in TCFMI can make the reference core mode more insensitive to environment.…”

Highly Sensitive Sensors Based on Photonic Crystal Fiber Modal Interferometers

“…In addition, the infiltration of the acetone vapor into the microscopic voids of the PCF is a diffusion process which is typically slow. We would like to point out that the combination of different fibers to form interferometers has been investigated during many years [58][59][60][61]. In these cases the splicing is critical since it determines the splitting and/or recombination of the interfering beams or mores.…”

Multimode-interference-structure optical-fiber temperature sensor with high sensitivity

“…MMI is generated by a simple structure consisting of a multimode fiber (MMF) sandwiched between single-mode fibers (SMF) at both ends. The MMI optical signal is highly sensitive to the refractive-index (RI) change of the medium surrounding the MMF; hence, it has been used in some RI sensor applications [3,4,5,6]. The influence of the coreless MMF diameter on the external RI variation of a liquid has been examined, and ultra-high sensitivity of the device to the variation in temperature in a high-RI liquid has been attained [7].…”