Active and Passive Q-Switched Tunable mJ Level Tm Laser

Tunable and milli-Joule level pulsed Tm based laser, are demonstrated in this paper. The spectral bandwidth was narrowed down to 0.15 nm FWHM. For the Actively Q-switched Tm:YLF laser, we achieved 33 nm of tunability range between 1873 nm and 1906 nm, using a pair of YAG Etalons. Using the same tunability technic for the Passively Q-switched Tm:YAP laser, we achieved 11 nm of tunability between 1930-1941 nm. The Tm:YLF laser was actively Q-switched using an acousto-optic modulator, while achieving mJ level pulse energy along the whole tuning range at a repetition rate of 1 kHz. Up to 1.97 mJ of energy per pulse was achieved at a pulse duration of 37 ns at a wavelength of 1879 nm, corresponding to a peak-power of 53.2 kW and at a slope efficiency of 36 %. The Tm:YAP laser was Passively Q-switched using Cr:ZnS saturable absorber (SA) as modulator, achieving mJ level pulse energy along the whole tuning range. Up to 1.2 mJ of energy per pulse was achieved at a pulse duration of 24 ns at a wavelength of 1935 nm, corresponding to a peak-power of 50 kW. The combination of both high energy pulsed lasing and spectral tunability, while maintaining narrow bandwidth across the whole tunability range, enhances the laser abilities, which could enable new applications in the sensing, medical and material processing fields. Which in the case of the of the Passively Q-switched Tm laser has a major advantage in terms of foot print.