Side Polished Fiber: A Versatile Platform for Compact Fiber Devices and Sensors

Abstract

Side polished fiber (SPF) has a controllable average roughness and length of the side-polishing region, which becomes a versatile platform for integrating multiple materials to interact with the evanescent field to fabricate all-fiber devices and sensors. It has been widely used in couplers, filters, polarizers, optical attenuators, photodetectors, modulators, and sensors for temperature, humidity, strain, biological molecules, chemical gas, and vector magnetic monitoring. In this article, an overview of the development history, fabrication techniques, fiber types, transmission characteristics, and varied recent applications of SPFs are reviewed. Firstly, the fabrication techniques of SPFs are reviewed, including the V-groove assisted polishing technique and wheel polishing technique. Then, the different types of SPFs and their characteristics are discussed. Finally, various applications of SPFs are discussed and concluded theoretically and experimentally, including their principles and structures. When designing the device, the residual thickness and polishing lengths of the SPF need to be appropriately selected in order to obtain the best performance. Developing all-fiber devices and sensors is aimed at practical usability under harsh environments and allows to avoid the high coupling loss between optical fibers and on-chip integrated devices.

Silver-TiO2 coated D-shaped photonic crystal fiber based SPR sensor for ultrasensitive refractive index detection: design and FEM analysis

“…The unique D-shaped geometry of the PCF provides a larger evanescent field, which enabling stronger coupling between the analyte and the sensing region, resulting in a higher sensitivity. Additionally, the D-shaped PCF enables easier coupling with light sources and detectors, simplifying the device setup and reducing fabrication complexity [31]. Chen et al conducted a study on an RI detection sensor utilizing an SPR-based D-shaped PCF, where a plasmonic material, such as gold, was employed.…”

Core-mismatched SPR temperature sensor based on silver and PDMS films

“…However, it can be fragile and lead to a reduction in structural strength, and the polishing depth and sensing length also have an effect on the sensor characteristics [6] . Besides, the preparation of polished shaped probes requires precis instruments, and the fragile structure of the probe makes it unsuitable to use in harsh detection environments [7][8][9] .In 2017, Velazquez-Gonzalez, J.S. et al designed a sensing probe with MMF-SMF-MMF structure for temperature sensing by coating the sensing unit SMF with a gold film and PDMS.…”

Tuning bimetallic Au@Ag nanorods localized surface plasmon resonance on side-polished optical fiber sensing configurations at near-infrared wavelengths

“…Another set of optical fiber structures, called side-polished fibers (SPF), exist. These structures present several advantages over the previous structures: they do not fragilize fibers significantly, do not create an interferometric pattern transmission profile, and allow for easy and precise structural modifications that can modify the core-guided modes without exciting higher-order modes in the case of SMF, or change the modes substantially in a MMF, while allowing for efficient evanescent coupling to the polished surface [7][8][9]. This work focus on SPF structures, which are usually developed in SMF.…”