Temperature sensing based on phase-to-intensity modulation conversion in fiber Bragg grating

In this paper, a method of temperature sensing based on microwave signal generation with fiber Bragg grating (FBG) as a frequency discriminator is proposed and experimentally demonstrated. According to the proposed approach, the optical carrier frequency is placed at the slope of the phase response of the FBG. The measure and to the phase of microwave signal generated by the frequency discriminator is mapped through an electrical spectrum analyzer. The proposal can describe the change in the flat area of the amplitude response, which improves the sensing resolution of the temperature near the center wavelength. Higher precision can be distinguished from the slope of the phase response. A result that the sensor responds to temperature with a sensitivity of 5.2dB/°C is achieved.