Abstract:Abstract-A real-time seawater temperature measurementsystem based on a wavelength swept distributed feedback laser isdeveloped. The i phase shifted Fiber Bragg grating with a narrowbandwidth of 12 pm is used as the sensing probe. The wavelengthis swept by linearly and periodically modulating the driving currentof laser with a sawtooth wave signal. The absorption line of H13C14Ngas cell provides a standard wavelength to calibrate the sweptwavelength in real time to reduces the measurement error inducedby the noises or drifts of the laser. Resonance difference betweenthe meas urement and the referen ce in time domain is obtained via aseries of digital signal processing such as normalization,derivation,lowpass filtering and cross-correlation operation.Experimental results show that, the sensitivity of the sensor is16.22 pm/C, the dynamic range is about 55 C, the resolution is ashigh as 0.002 °C, and the thermal response time is -50 ms. The sensor system is compact,simplc,tem perature monitoring.