High-energy single-longitudinal-mode Q-switched double-cladding fiber laser based on the injection seeding technique

This paper demonstrates a high-energy, single-longitudinal-mode (SLM), actively Q-switched fiber laser based on the injection seeding technique. The large-mode-area double-cladding fiber is used as the gain medium to improve energy storage. Simultaneously, by using the linear electro-optic effect of the negative uniaxial crystal (β-B a B ₂ O ₄, BBO), a matching frequency-shift-free Q-switch with high damage threshold and high extinction-ratio is designed. Before reaching the stimulated Brillouin scattering threshold, the SLM Q-switched pulses can be achieved with energy higher than 15 µJ over a wide range of repetition rates from 10 to 80 kHz, and the maximum output power reaches 1.2 W at the repetition rate of 80 kHz, which may be the highest output pulse energy for such a SLM Q-switched fiber laser so far, to our best knowledge.