光学微球谐振腔由于其具有超高的Q值及极小的模式体积等优点,在高灵敏度传感和光通信等方面得到了广泛的研究。测试了未封装和封装后微球腔谐振波长随温度的变化,实验结果表明随温度增大,谐振波长线性红移,且线性度高。二者温度系数不同,未封装时为25.6 pm/℃,封装后为4.4 pm/℃,主要原因为紫外胶的负热光系数所致。理论分析了紫外胶的热光效应,通过控制紫外胶厚度可以改变光在紫外胶中的比例,从而调节温度系数。当光在紫外胶中比例为0.1135时,温度系数变为0,可以抑制温度漂移,实现了温度补偿;该比例继续增大,温度灵敏度提高。低温漂、高灵敏度、微型化拓宽了回音壁模式(WGM)传感器的应用潜力。
Optical microsphere resonant cavity has been widely researched in the field of high sensitivity sensor and optical communication because of its high Q value and minimal model volume. Optical resonance wavelength shifts are measured with temperature changes for unpackaged and encapsulated microsphere. Linear dependence of red shift against temperature rise with high linearity is observed. The temperature cofficient is 25.6 pm/℃ for unpackaged microsphere, whereas is 4.4 pm/℃ for encapsulated one, which mostly results from ultraviolet(UV)glue′s negative thermo-optic coefficient. The thermo-optic effect is analyzed based on UV glue. The fraction of light in UV glue can be changed by the thickness of glue, and then, temperature coefficient is also changed. The temperature coefficient decreases to zero when the fraction is 0.1135, which means the depression of temperature drift as well as the realization of thermal compensation. Sensitivity of temperature is improved as fraction increases.Suppressed temperature drift, improved sensitivity, and miniaturization enables broad application potentials of whispering-gallery mode(WGM)-based sensors.