High energy, high repetition rate, tunable Er-Yb-codoped Q-switched fibre laser

Summary form only given. High energy, Q-switched pulses with high average power and low M/sup 2/ value at eye-safe wavelength (1.55 /spl mu/m) are of particular interest for many technological applications e.g. nonlinear frequency conversion, LIDAR. The maximum extractable energy from a single mode fibre is, however limited to /spl sim/10 /spl mu/J due to small cross-sectional area of standard single-mode cores. In this paper we described a high energy, ytterbium sensitised erbium doped, Q-switched, double-clad (DC) fibre laser. The laser is tunable from 1537 nm to 1570 nm with a M/sup 2/ value of <1.05. More than 95% of the total output power was preferentially polarised in one transverse direction and about 65 /spl mu/J of energy per pulse can be extracted from this laser at a repetition rate of 10 kHz.