Highly Sensitive Axial Strain Fiber Laser Sensor Based on All-Fiber Acousto-Optic Tunable Filter

In this letter, we propose and demonstrate a highly sensitive axial strain fiber laser sensor based on all-fiber acousto-optic tunable filter (AOTF). In the laser sensing system, all-fiber AOTF acts as a band-rejection filter of the fiber laser sensor and the sensing head used for axial strain measurement. When the axial strain is loaded, the optical resonant wavelength of all-fiber AOTF moves to the long wavelength region, resulting in the increasing of the central wavelength of the fiber laser sensor. The proposed fiber laser sensor takes the advantages of high-optical signal-to-noise ratio and narrow bandwidth. Moreover, the fabrication of all-fiber AOTF is also very simple. Experimental results show that a good linearity is obtained between the axial strain and central wavelength of the proposed fiber laser sensor, and a high sensitivity of ~0.148 nm/με with the range of 0-160 με can be successfully achieved.