Comparison of compact lasers Nd:YAG/V:YAG and Nd:YAP/V:YAG generating in the 1.3μm spectral region

Abstract

The aim of this work was to design a compact Q-switched laser generating radiation in the 1.3 μm spectral region. Two active materials, Nd:YAG and Nd:YAP, were used to construct such a compact laser with stable nanosecond pulses which could be used as a laser source of LIDAR for autonomous vehicle control. A constructed laser was pumped longitudinally by a fiber-coupled laser diode (core diameter 400 μm, numerical aperture 0.22) in a pulse regime at a wavelength of around 805nm in the range of repetition frequencies of 10 − 500 Hz. A V:YAG saturable absorber with an initial transmission of 85% was used to achieve the Q-switched regime. The pumping resonator dielectric mirror had a high transmission for pumping radiation and high reflectivity for generated 1.3 μm radiation. The output resonator dielectric mirror reflectivity was 90% @ 1.3 μm. The Nd:YAG/V:YAG laser provided radiation at a wavelength of 1318nm with pulse energy up to 162 μJ, pulse length ∼ 13.5 ns, and pulse peak power up to 12.3 kW. With the Nd:YAP/V:YAG compact laser generating at a wavelength of 1342 nm, a pulse energy of up to 193 μJ, pulse length ∼ 11.8 ns, and pulse peak power up to 16.2 kW, was achieved. Generated pulse energy and peak power decay with increasing pumping frequency was steeper in the case of Nd:YAP/V:YAG laser due to poorer thermal conductivity of Nd:YAP crystal compared to Nd:YAG crystal. On the other hand, the Nd:YAP/V:YAG laser showed better stability of the wavelength and polarization of the output radiation. In the case of both lasers, linearly polarized radiation with TEM00 single-mode spatial profile was generated.