Fiber Bragg grating based linear cavity fibre laser temperature sensor with enhanced optical signal-to-noise ratio

摘要

An optical temperature sensor based on linear cavity erbium-doped fiber laser is proposed in this work. A fiber Bragg grating is utilized in the laser cavity as the sensor head for temperature detection. Experimental results suggest that the laser wavelength has linear relationship with temperature. As the temperature increases from 25 C to 55 C, the laser wavelength shifts linearly from 1550.168?nm to 1550.524?nm with the recorded sensitivity of 11.7 pm C-?1. The laser is also found to be stable with fluctuation of less than 0.42 dB and it has 3 dB linewidth of 0.024?nm. Moreover, the laser has high optical signal-to-noise ratio (OSNR) of 55 dB and this arises from the use of linear cavity in this design. Resulting from the signal amplification that happens twice in the linear cavity for a round trip, the laser gets high power and this enhances the laser OSNR. The high OSNR of the laser is beneficial to improve the sensor detection limit.