Single transverse mode Yb-doped fiber laser generating up to 0.5mJ/11W with flexible pulse parameters

We demonstrate a single transverse mode Yb-doped fiber laser that can be operated in a wide range of pulse lengths and repetition rates. The pulsed 1064nm beam of a single mode diode laser is amplified by a three stage fiber amplifier. It consists of two stages that incorporate single-mode fibers and a third stage using LMA fiber. A monolithic setup is achieved by an adiabatic taper between the second and the third stage exciting only the fundamental mode in the LMA fiber. Variable pulse regimes were investigated in the range from 10kHz to 1MHz and CW. A maximum output energy of 0.5mJ and maximum peak power of 66kW were measured. Pulse trains consisting of four pulses with pulse spacing of 200, 500 and 1000ns and a pulse length of 10ns were also evaluated. The repetition rate of the train was set to 1kHz.