Comparative Study on Sensing Properties of Fiber-Coupled Microbottle Resonators With Polymer Materials

Abstract

Optical whispering gallery mode (WGM) microbottle resonators based on a variety of polymer materials (benzocyclobutene (BCB), UV88 (Relentless, China) and Loctite3525 (HenKel, Germany)) were fabricated and investigated experimentally. The polymer materials were spin-coated onto the fiber and cured by ultraviolet (UV) light followed by heating to form a microbottle structure of different shapes and diameters. The WGMs were excited by tapered fiber, and the spectral characteristics of all realized microbottle cavities were evaluated, such as quality factor (Q > 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ), free spectral range and polarization mode (TE and TM). The temperature and refractive index (RI) sensing performance are analyzed and Q-factor changes during the sensing process. In addition, a newly application of UV light intensity sensing for the polymer microbottle resonators was also demonstrated firstly. According to the experimental results that the microbottle resonator of BCB displays good UV light intensity sensitivity (0.0011 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nm</i> /( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mw/cm</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> )) and figure of merit (FOM) (0.0122/( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mw/cm</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> )). This sensor is a simple structure, low-cost material, robust performance, and possesses attractive application prospects in sensing and optical devices.