Research on strain sensing based on passively mode-locked fiber laser using saturable absorber

Based on a passively mode-locked fiber laser, we proposed a new method of strain sensing. The laser cavity optical length variation, mainly caused by strain and temperature, is corresponded with the repetition frequency change which can be easily measured by spectrum analyzer. Theoretical calculation shows that the device can measured nano-strain in the optical fiber. Experimental result shows that the sensing signal is very sensitive to the environmental change.