Temperature sensing characteristics of a microsphere resonator embedded in a capillary

The coupling mechanism and temperature sensing characteristics based on the micro-sphere resonant cavity coupled apparatus embedded in capillary were investigated. The micro-sphere support the high-order modes, which is easy to meet the phase matching condition with the modes in the quartz capillary, thus the mode of micro-sphere echo wall will be excited. The temperature sensing of a barium titanate micro-sphere was tested. A polymethylmethacrylate (PMMA) micro-sphere was adopted to carry out the temperature sensing experiment for further enhancing the sensing sensitivity. The experimental results show that the temperature sensing sensitivity of PMMA micro-sphere can reach to 83.9 pm/℃, about eight times of that by the barium titanate micro-sphere, which plays an important role for improving the temperature sensing sensitivity.