Damage analyses between Q-switched Tm-doped yttrium aluminum garnet and yttrium aluminum perovskite lasers and the application in thermoplastics processing

In this paper, we demonstrate damage analyses between Q-switched Tm-doped yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP) lasers with identical resonator configuration and demonstrate application of the pulsed Tm laser for transparent polymer processing. In the AO Q-switched Tm:YAG laser, shortest pulse width of 41 ns is obtained at 1 kHz with a peak power of 165.7 kW. However, owing to the distorted lattice and the resulted self-pulsing, Tm:YAP crystal is apt to damage at room temperature during Q-switching with low repetition frequencies, where maximum pulse energy of 2.73 mJ is obtained at 5 kHz. The results indicate that Tm:YAG laser is prone to operate at low PRFs (< 5 kHz) for high pulse energy and Tm:YAP laser is more suitable to achieve high average power at high PRFs due to its high emission cross section. Finally, a material processing platform basing on the pulsed Tm laser is built, where the marking and welding of thermoplastic PMMAs are explored compared to a common CW Tm laser. The results show the advantage of Q-switched Tm lasers in material processing, especially for transparent thermoplastic marking, welding or sealing during the scenarios such as biochemical researches and medical surgeries.