Micro-Temperature Sensor based on Optical Whispering Gallery Mode of Fiber Taper-Microsphere Coupling System
نویسندگان
چکیده
Miniaturized Whispering Gallery Mode (WGM) temperature sensor has great potentials of high resolution and great on-chip integration capability. This study focuses on the development of this kind of sensor based on the shifting wavelength of the optical resonance due to thermal expansion and thermo-optic effects of a silica microsphere. Excellent linear dependence of the wavelength shift versus temperature rise is observed for three sizes of microspheres (D=90μm, 145μm and 313μm) in small temperature ranges (≤17K) at very low temperatures (113±1K to 173K). By comparing this observation with the results of similar sizes of microspheres of our previous study in near room temperature as well as with a theoretical analysis, a conclusion is drawn that thermal expansion and thermal optic coefficients need to be further studied for microscale silica materials. Ultra high resolution sensing capability as well as potentials of integrated & miniaturized applications of the WGM temperature sensor is discussed. A method is designed to initially characterize the WGM temperature measurement noise level due to self-heating effect of the WGM resonance.
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