Electro-optic active Q-switched Tm:YLF laser based on polarization modulation

An electro-optic active Q -switched Tm:YLF laser (1880 nm) employing a novel, to the best of our knowledge, switching scheme is presented. The switching is done by a potassium lithium tantalate niobate (KLTN) crystal operated slightly above the ferroelectric phase transition, cut in a trapezoidal shape for reducing acousto-optic oscillations. The novel switching scheme exploits the emission cross section difference between the π and σ polarizations in the Tm:YLF and overcomes the residual oscillation effects even at high repetition rates. The laser exhibited stable operation yielding pulses of 0.81 mJ and pulse duration of 30 ns at 5 kHz, and pulses of 1.25 mJ and pulse duration of 19 ns at 500 Hz.