kW pulsed nanosecond TDFL with direct modulation

We present a kW level pulsed laser based on a master oscillator power amplifier (MOPA) configuration. The directly modulated single frequency laser at 1952 nm was pulsed in the nanosecond regime with a repetition rate frequency from 10 kHz to 2 MHz. The MOPA topology was based on a two stage amplifier using single clad Thulium-doped fiber: it consisted of a pre-amplifier stage followed by a booster stage. We investigated the performance of this pulsed laser for two different TDFs with different saturating energies in the booster stage. The direct modulation allowed us to demonstrate more than 1 kW of output peak power over pulse repetition frequencies from 10 kHz to 500 kHz. For a pulse duration of 21 ns, we measured output energy of 13 µJ and 29 µJ for booster fiber saturating energies of 15 µJ and 30 µJ, respectively.