Influence of surface curvature on mode and sensing characteristics of quartz capillary microbottles

In order to design micro-bottles with best sensing characteristics, such as high Q value and low mode volume, mode characteristics and refractive index sensing characteristics of quartz capillary micro-bottles were studied by means of finite element numerical analysis. The influence of different surface curvatures on mode characteristics of echo wall of hollow core and liquid core micro-bottles, including quality factor and percentage of core energy, was calculated and analyzed. The variation of resonance wave length with surface curvature in refractive index sensing application was also discussed. The results show that the 2nd tangential order mode is more affected by curvature of inner wall. Q value is up to 10⁸ when curvature square of inner wall Δk₂²=0.008. The smaller the inner wall surface curvature is, the greater the energy of core percentage is. High sensitivity refractive index can be realized by the smaller curvature of inner wall. This study provides an effective basis for further development and application of high Q value microbottles in sensing field. It has certain theoretical reference value.