Linewidth narrowing and frequency stabilization of a coin-sized laser module

Abstract

We demonstrate linewidth narrowing and frequency stabilization of a coin-sized laser module using both a short imbalance path length Michelson fiber interferometer and Doppler-free spectroscopy of molecular iodine. The linewidth of the coin-sized laser is reduced from 2 MHz to 6 kHz, which is now narrower than the Doppler-free spectral linewidth (670 kHz) of molecular iodine. Laser frequency stabilization based on the Doppler-free iodine signal is carried out by directly controlling the imbalance path length of the fiber interferometer. The frequency stability of the hybrid-locked coin-sized laser is 9.8 × 10−13 at 1-s averaging time and reaches 6.8 × 10−14 at 400 s. The hybrid-locked coin-sized laser with linewidth narrowing and frequency stabilization has a long coherence time and known absolute frequency and can be used for precision measurements in either fundamental science or industrial applications.