Whispering gallery modes in a single silica microparticle attached to an optical microfiber and their application for highly sensitive displacement sensing

A compact and relatively stable structure is experimentally demonstrated to excite whispering gallery modes (WGMs) in a single chemically fabricated silica microparticles with a diameter of around 10.6 mu m attached to an optical microfiber. The resonance dip with an extinction ratio of 14 dB and Q factor of around 300 has been achieved. Based on the WGMs in this structure, an in-line fiber-optic displacement sensor is presented with a high sensitivity of 33 dB/mm and a measurement range of over 400 mu m. The measurement resolution of this displacement sensor can reach to similar to 10 mu m. The good reversibility and repeatability are also verified. This work offers a scheme to observe the WGMs in a single silica microparticles and demonstrates their application for in-line highly-sensitive displacement sensing. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement