A Stabilized Fiber Laser for High-Resolution Low-Frequency Strain Sensing

We frequency stabilize a fiber laser for use in low-frequency sensing applications. Using a radio frequency locking technique, an Erbium-doped single longitudinal mode fiber laser is stabilized to a Mach–Zehnder interferometer. The low-frequency fiber laser noise was suppressed by more than 1.5 orders of magnitude at frequencies below 300 Hz reaching a minimum of 2 ${rm Hz}/sqrt {rm Hz}$ between 60 and 250 Hz. The corresponding strain sensitivities are 2 ${rm p}epsilon /sqrt {rm Hz}$ at 1 Hz and 15 ${rm f}epsilon /sqrt {rm Hz}$ from 60 to 250 Hz.