Passively Q switched dual channel Tm:YLF laser by intracavity spectral beam combination with volume Bragg gratings

A novel dual channel Tm:YLF laser system was developed where two degenerate laser cavities were coupled by spectrally beam combining their emission and by implementing a common output coupler. Under continuous wave running conditions, each channel's slope efficiency was greater than 45% and the maximum combined output power was 11 W. Passive Q-switching was achieved using an 80%, Cr:ZnSe saturable absorber. The output pulses had a maximum energy of 5.8 mJ and duration of 90 ns (65 kW of peak power) at 5.7 W of absorbed pump power. Each channel showed less than 1 mn of spectral width with central wavelengths around 1880 nm and 1908 nm correspondingly. The system had adjustable spectral difference between the channels ranging from 5 to 20 mn which corresponds to 0.4 - 1.7 THz if the system is used for nonlinear difference frequency generation. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement