Single-Mode Operation with no Mode-Hops of a 110m Long Brillouin Fiber Laser with Non-Resonant Pumping

Stimulated Brillouin scattering (SBS) has received much attention for decades for its numerous applications in sensors, optical amplification or design of narrow-linewidth lasers. In particular, optical fibers present Brillouin gain with a narrow bandwidth of a few tens of MHz. This permits to realize Brillouin fiber lasers (BFL) emitting Stokes lines with potential ultra-narrow linewidths [1]. Standard architectures are based on the use of a long fiber loop in order to provide sufficient gain. The loop is then resonant for the pump requiring servo-control to lock the pump frequency to the loop resonance. Furthermore, the whole pump power may not be injected in the cavity, as the pump spectrum may be broader than the cavity resonance. Conversely, non-resonant pumping enables to fully exploit the pump power. However, as the pump-resonator detuning may drift, it suffers from mode-hopping of the Stokes wave.