Wavelength Lock-in Technique to improve Fiber Interferometer Performance for Geophysics Applications

An automatic wavelength lock-in technique is proposed to improve fiber interferometer performance for geophysics application. The proposed approach locks the laser wavelength to the absorption lines of hydrogen fluoride gas. The lock-in scheme directly benefits from the dithering signal driving the laser to obtain the required quadrature phase shift for displacement reconstruction and thus does not affect the sensor operation.