Fused Microknot Optical Resonators in Folded Photonic Tapers for in-Liquid Durable Sensing

Abstract

Optical microknot fibers (OMFs) serve as localized devices, where photonic resonances (PRs) enable self-interfering elements sensitive to their environment. However, typical fragility and drifting of the knot severely limit the performance and durability of microknots as sensors in aqueous settings. Herein we present the fabrication, electrical fusing, preparation, and persistent detection of volatile liquids in multiple wetting–dewetting cycles of volatile compounds and quantify the persistent phase shifts with a simple model relating to the ambient liquid, enabling durable in-liquid sensing employing OMF PRs.

Vapor Sensing with Polymer Coated Straight Optical Fiber Microtapers Based on Index Sensitive Interference Spectroscopy of Surface Stress Birefringence

“…Sensing using optical methods has been an active field of research in recent years [1][2][3], due to the inherently superior capabilities offered by complex photonic structures [4,5]. Specifically, microstructures incorporated within optical fiber tapers transmitting near-infrared (NIR) light have found comprehensive applications in a variety of sensing scenarios, including in liquid [6][7][8][9], gas [10,11], and other physical [12][13][14][15][16] and chemical [17,18] media. In particular, the chemically inert nature of silica fiber [19] and Si substrates [20] makes their combination a leading platform for integration with reactive layers for controllable chemically-sensitive response tailored to vapor specificity [21,22], and measuring additional quantities such as temperature together with the vapor content [23].…”