Compact high-energy Q-switched cladding-pumped fiber laser with a tuning range over 40 nm

We describe a compact Q-switched diode pumped double-clad ytterbium-doped f iber laser. The fiber laser was bidirectionally pumped by two laser diodes (2 W of output power each) via:two side-injecting pump-couplers. We used a large multimode core of 15 mu m diameter to increase the laser gain volume and thus to achieve higher pulse energy. Experimentally this laser produced pulses with energy up to 170 mu J with a peak power of 2 kW (at a low repe tition rate of 500 Hz) and was tunable from 1060 to 1100 nm.