Abstract:

The mechanism of coupled evanescent wave temperature sensors is analyzed with the theory of strong coupling. A temperature detection system based on a micro-controller is designed. To eliminate circuit noise, hardware and software filters are introduced to improve stability of the temperature detection system. The optical spectrum of LD light sources will change with the ambient temperature. This will cause instability and poor precision of the detected temperature due to the relationship between wavelength and the coupling ratio. To deal with this problem, the microcontroller's embedded temperature sensor is proposed to use to compensate for the errors in the temperature detected by the optic fiber sensor. Experiments show that the temperature precision can reach ±1 ℃.

Key words:
software compensation, evanescent wave, wavelength shift, theory of strong coupling