Stabilized single-frequency sub-kHz linewidth Brillouin fiber laser cavity operating at 1 µm.

Abstract

We experimentally demonstrate a stabilized single-frequency Brillouin fiber laser operating at 1.06µm by means of a passive highly nonlinear fiber (HNLF) ring cavity combined with a phase-locking loop scheme. The stimulated Brillouin scattering efficiency is first investigated in distinct single-mode germanosilicate core fibers with increasing G e O 2 content. The most suitable fiber, namely, 21mol.% G e O 2 core fiber, is used as the Brillouin gain medium in the laser cavity made with a 15-m-long segment. A Stokes lasing threshold of 140mW is reported. We also show significant linewidth narrowing (below 1kHz) as well as frequency noise reduction compared to that of the initial pump in our mode-hop free Brillouin fiber laser.