Abstract

We propose and demonstrate a multi-point, self-adaptive fiber ultrasonic sensor based on fiber Bragg gratings (FBGs). The sensor is constructed from matched FBG pairs (FBGPs) and a tunable optical filter in a fiber ring laser. FBGPs with different Bragg wavelengths are used as both the comb filter to produce potential lasing lines and the ultrasonic sensing elements. The ultrasonic signal is directly detected by monitoring the intensity response at each laser channel to the cold-cavity loss modulation from the spectral shift of matched FBGPs. The laser channel between the FBGPs is actively switched using the tunable optical filter, thereby achieving multi-point and switchable detection yet avoiding mode competition in the lasers. Meanwhile, to achieve self-adaptability, the two FBGs of the FBGP are fixed side by side at the same location of the structure such that both FBGs respond similarly to static strain and temperature variation. The multi-point system is promising for the robustness in the practical applications because it is insensitive to static strain ranging over 1400 με and temperature variation from 20 °C to 50 °C, respectively.

© 2018 IEEE

Adaptive ultrasonic sensor using a fiber ring laser with tandem fiber Bragg gratings

Tongqing Liu, Lingling Hu, and Ming Han
Opt. Lett. 39(15) 4462-4465 (2014)

Multiplexed fiber-ring laser sensors for ultrasonic detection

Tongqing Liu, Lingling Hu, and Ming Han
Opt. Express 21(25) 30474-30480 (2013)

Fiber Bragg grating dynamic strain sensor using an adaptive reflective semiconductor optical amplifier source

Heming Wei, Chuanyi Tao, Yinian Zhu, and Sridhar Krishnaswamy
Appl. Opt. 55(10) 2752-2759 (2016)

Waveform reconstruction for an ultrasonic fiber Bragg grating sensor demodulated by an erbium fiber laser

Qi Wu and Yoji Okabe
Appl. Opt. 54(4) 694-698 (2015)

Intensity-demodulated fiber-ring laser sensor system for acoustic emission detection

Ming Han, Tongqing Liu, Lingling Hu, and Qi Zhang
Opt. Express 21(24) 29269-29276 (2013)