Single frequency Q-switch diode-pumped solid-state microchip laser

Summary form only given. The results of single frequency high repetition rate (up to 111 kHz) subnanosecond pulses generation investigated both theoretically and experimentally for solid-state diode-pumped microchip laser on YVO₄:Nd³⁺ with passive Q-switch on garnet doped by Cr⁴⁺ are presented. High value of laser transition cross section is the advantage of YVO₄:Nd³⁺ as an active medium. Thus short pulses should be received in monopulse operation mode. But it is difficult to lase these pulses due to low ratio of the corresponding cross sections of available Q-switch and active element. It is shown that poor relationship between saturation energies of the involved elements can be enhanced by suitable selection of pumping and cavity configuration parameters. The cavity Fresnel number is determined by the trade-off between high threshold for radiation dual pulses oscillation and maximal aspect ratio of beams apertures at the elements. The axial mode shaping occurs in dynamic conditions of "soft" pin-holes apertures fluctuating. These "soft" pin-holes are constituted by population inversion distribution in the active element and radiation transparency distribution of Q-switch. The mode shaping rate is determined by compliance of inversion volume and generated radiation volume in the active element. The single frequency generation process is discussed. The train of single frequency fundamental mode single pulses lasing with repetition rate up to 111 kHz, duration down to 0.6 nsec and peak power up to 1.6 kW in Q-switch YVO₄:Nd³⁺ microchip laser pumped by power of 0.85 W of laser diode was observed experimentally.