Single cut technique for adjustment of doubly resonant Brillouin laser cavities.

We report a simple technical solution for precise adjustment of short fiber cavities commonly used with Brillouin fiber lasers. The technique is based on recording the Brillouin response of the cavity to the frequency scanned laser radiation. The recorded traces are used to calculate the excess cavity length that needs to be removed from the original cavity to provide its precise adjustment to the Brillouin resonance at any preselected pump laser wavelength. The adjusted laser cavity is simultaneously resonant for pump and Stokes radiation. For demonstration of the approach, fine adjustment of a 4 m long ring cavity based on standard Corning SMF-28 fiber is performed.