Multimode microfiber interferometer for dual-parameters sensing assisted by Fresnel reflection

This work implements and demonstrates an interferometric transducer based on a trimodal optical waveguide concept. The readout signal is generated from the interference between the fundamental and second-order modes propagating on a straight polymer waveguide. Intuitively, the higher the mode order, the larger the fraction of power (evanescent field) propagating outside the waveguide core, hence the higher the sensitivity that can be achieved when interfering against the strongly confined fundamental mode. The device is fabricated using the polymer SU-8 over a SiO2 substrate and shows a free spectral range of 20.2 nm and signal visibility of 5.7 dB, reaching a sensitivity to temperature variations of 0.0586 dB/ ∘ C. The results indicate that the proposed interferometer is a promising candidate for highly sensitive, compact and low-cost photonic transducer for implementation in different types of sensing applications, among these, point-of-care.

Section: Resultsmentioning

confidence: 71%

Trimodal Waveguide Demonstration and Its Implementation as a High Order Mode Interferometer for Sensing Application

Ramirez

Gabrielli

Lechuga

et al. 2019

“…In 2014, Yao et al demonstrated a graphene-based microfiber multimode interferometer, as shown in Figure 10 a [ 46 ]. In this structure, the HE 21 mode is more sensitive to local refractive index alteration than the in-core HE 11 [ 90 ], hence its interference Free Spectrum Range (FSR) could be tuned by gas adsorption, resulting in a spectral resonance dip shift. In a sensing experiment, ~0.1 ppm for NH 3 gas detection and ~0.2 ppm for H 2 O vapor detection were achieved.…”

Section: Graphene Gas Sensors With Microfibersmentioning

confidence: 99%

Optical Graphene Gas Sensors Based on Microfibers: A Review

Yao

et al. 2018

Graphene has become a bridge across optoelectronics, mechanics, and bio-chemical sensing due to its unique photoelectric characteristics. Moreover, benefiting from its two-dimensional nature, this atomically thick film with full flexibility has been widely incorporated with optical waveguides such as fibers, realizing novel photonic devices including polarizers, lasers, and sensors. Among the graphene-based optical devices, sensor is one of the most important branch, especially for gas sensing, as rapid progress has been made in both sensing structures and devices in recent years. This article presents a comprehensive and systematic overview of graphene-based microfiber gas sensors regarding many aspects including sensing principles, properties, fabrication, interrogating and implementations.

“…Among them, Zhang [21] composed a SMF-no core fiber-SMF cascaded with two FBGs, the reported sensitivity are 199.6 dB/RIU (in the range of 1.33-1.37) and 355.5 dB/RIU (in the range of 1.37-1.40) by utilizing an intensity difference method. Moreover, tapering is a convenient technical means to improve the RI sensitivity since it can effectively increase the contact area between the in-fiber light power and the external liquid, an enhanced evanescent field as a medium for power exchange at the same time [24][25][26]. Kong [26] designed a hybrid multi-mode interferometer which consisting of a thin core fiber taper and an air bubble fabricated by the arc discharge technique, which exhibits a high RI sensitivity of 442.59 dB/RIU.…”

Section: Introductionmentioning

confidence: 99%

Up-down Taper Based In-Fiber Mach-Zehnder Interferometer for Liquid Refractive Index Sensing

Han

Liu

Jiang

et al. 2019

A novel in-fiber Mach-Zehnder interferometer based on cascaded up-down-taper (UDT) structure is proposed by sandwiching a piece of polarization maintaining fiber between two single-mode fibers (SMF) and by utilizing over-fusion splicing method. The dual up tapers respectively act as fiber splitter/combiner, the down taper acts as an optical attenuator. The structure parameters are analyzed and optimized. A larger interference fringe extinction ratio ~15 dB is obtained to achieve refractive index (RI) sensing based on intensity demodulation. The experimental results show that the RI sensitivity is −310.40 dB/RIU with the linearity is improved to 0.99 in the range of 1.3164–1.3444. The corresponding resolution can reach 3.22 × 10−5 RIU, which is 6.8 times higher than wavelength demodulation. The cross sensitivity which caused by temperature fluctuation is less than 1.4 × 10−4.