Widely tunable, pulsed Tm:YAP laser based on Active / Passive Q-switching and YAG etalons

A wide range of applications in the 2 μm spectral regime require a variety of laser system specifications such as pulse energy, pulse durations, peck power and repetition rate. Wavelength tunabilty may be advantageous in some laser systems but in others it is essential. While there are many reports of tunable CW lasers, options for pulsed mode lasers are very limited and generally display low performance. Two configurations of pulsed, tunable, Q-switched, Tm:Yap lasers developed in our lab are presented. In both cases, the tunability was achieved utilizing one or two Yttrium aluminum garnet (YAG) etalons in the laser cavity. The first design utilized an acousto-optic modulator (AOM) as an active Q-switch, achieving a combination of high-pulsed energies up to 2.3 mJ and tunability between 1926 - 1961 nm, with a narrow bandwidth of 0.15 nm Full Width Half Maximum (FWHM) and a pulse duration of 30 ns at 1 kHz repetition rate. The second design demonstrates for the first time wide tunabilty using a passive Q-switch element in the cavity. In this setup wavelength tunability ranging from 1911 - 1952 nm was achieved, with maximal energy per pulse of 1.42 mJ, pulse durations of 26-36 ns at a maximal repetition rate of 3 kHz. The simultaneous combination of these laser features in the same cavity; tunability range, narrow bandwidth, output power, pulse durations and repetition rate make these lasers a promising tool in the biomedical field, for sensing, and material processing applications.