Patent ID: 7577178

Claim:
A narrow-linewidth injection seeded Q-switched fiber ring laser, comprising: a ring formed of a single-clad Er-doped optical fiber having a core, an acoustic layer, and a pure silica cladding, the core, the acoustic layer, and the pure silica cladding structured such that an L 01 acoustic mode of the optical fiber is removed as a dominant mode, the Er-doped optical fiber having a predetermined length and an effective Brillouin gain coefficient of less than 0.5×10 −11 m/W; two isolators operatively coupled to the optical fiber to effect unidirectional laser operation; a wavelength division multiplexer operatively coupled to the ring, the wavelength division multiplexer coupling pump light into the ring; a coupler operatively coupled to the ring, the coupler having a first arm that is a laser output, the coupler forming part of the ring, and a second input arm into which seed power is launched; and a Q-switch operatively coupled to the ring.