Generation of widely wavelength tunable Q-switched pulses in an ytterbium doped all-fiber laser

We report an all-fiber, broadband wavelength-tunable, acousto-optic Q-switched ytterbium-doped fiber laser. The tunable lasing operation was achieved by fiber-based acousto-optic tunable filter with a wavelength range spanning to more than 70 nm from 1008.6–1080.3 nm. Pulse shortening is achieved by spectral filtering and reducing the duty cycle of the acousto-optic modulator (AOM) used for Q-switching. At a 345 mW pump power and 1030 nm laser operation, the duration of Q-switched pulses is reduced from 110 ns (without spectral filtering) to 65 ns with 2.2 μJ pulse energy at a 10 kHz repetition rate and 10% duty cycle of AOM. The Q-switched pulse duration is further shortened to ∼10 ns by reducing the duty cycle of AOM to 0.12%. We believe that this all-fiber integrated Q-switched laser system with wide wavelength tunability and shorter duration pulses will be useful in many scientific applications. (paper)