Package of hollow micro-bottle resonator and refractive index sensing properties

To improve the stability and portability of the sensor, a refractive index sensor based on hollow micro-bottle resonator was proposed to package the system and study its refractive index sensing properties. The optical field distribution of radial echo-wall mode of hollow micro-bottle resonator under different wall thicknesses was simulated and analyzed. The proportion of the optical field inside the micro-bottle increased with the decrease of wall thickness of device, which was beneficial to improve the sensing sensitivity. To reduce the wall thickness, the quartz capillary was etched by hydrofluoric acid, which was used to fabricate the thin-wall hollow micro-bottle resonator by fusion splicer. The coupling system was packaged and fixed on a slide by using UV adhesive, which enhanced the stability and portability of the sensor. Finally, the sensing characteristics of the packaged device under different refractive index matching fluids were studied and the sensing sensitivity was 26.50 nm/RIU. The proposed sensor has the advantages of high stability, high flexibility and low loss, which has great application potential in optofluidic refractive index detection.