Brillouin Assisted Optoelectronic Self-Narrowing of Laser Linewidth

Standard laser linewidths typically range from 10 kHz for solid-state lasers up to a few MHz for semiconductors. Several techniques have been developed in the past in order to reduce lasers linewidths to sub-kHz level. It can be achieved by servo-locking the mean laser frequency to a reference frequency provided by an atomic or molecular absorption line, leading to long-term frequency stabilization. However, it does not generally offer significant reduction of short-term phase-noise. Other techniques consist in using the resonances provided by ultra-stable cavities or km-imbalanced interferometers. These methods are accurate, but are very sensitive to environmental noise which degrades the laser linewidth. Injection locking provides alternative solutions for linewidth narrowing, but the problem is merely deferred as they rely on the use of stabilized low-noise optical seeders. Besides Brillouin fiber lasers (BFL) employing the stimulated Brillouin scattering (SBS) in fibers are known to present intrinsic narrow sub-kHz linewidths [1]. We show here how the benefits of using a solidstate laser, in terms of power, and SBS, in terms of spectral purity, can be easily combined.