978 nm Single Frequency Actively $Q$ -Switched All Fiber Laser

A single-frequency actively Q-switched all-fiber laser at 978 nm was developed using a 2-cm-long commercial ytterbium-doped silica fiber and a pair of silica-fiber-based Bragg gratings. The Q-switching is enabled by the stress-induced polarization modulation in the short linear fiber laser cavity. The laser generates actively Q-switched single-frequency laser pulses with a pulse repetition rate ranging from tens of kilohertz to hundreds of kilohertz. The pulse duration and the average/peak power have been characterized. This is, to the best of our knowledge, the first demonstration of a single-frequency all-fiber Q-switched laser below 1 μm using commercial highly ytterbium-doped silica fiber.