Generation of two identical ns laser pulses spaced by a single µs time interval by means of sequential switching of the output mirror transmittance in a diode-pumped Nd:YAG laser is reported, to our knowledge, for the first time. The theoretical study of the process of transmission losses switching is developed. This analysis confirms the possibility of generation of two identical Q-switched laser pulses with 100% efficiency with respect to the referenced single pulse energy. The detailed characterization of the laser in free-running, single and double Q-switching regimes is presented. The laser can be applied in different branches of metrology as PIV, LIBS or holographic interferometry.

We demonstrate MW-level, single resonance optical parametric oscillator, based on KTP Type-II crystal with noncritical phase-matching. The OPO is pumped by electro-optically Q-switched Nd:YAG slab laser providing 55 mJ of pulse energy. At the output, we achieved 28 mJ of signal pulse energy at 1.57 μm with 51% conversion efficiency, corresponding to 1.4 MW of peak power.

An efficient operation of a Ho:YLF laser pumped by a Tm-doped fibre laser is reported. The research in a continuous-wave (CW) operation was done for two crystals of the same 0.5 at.%Ho dopant concentration and with different lengths (3×3×30 mm³ and 3×3×50 mm³). For an output coupling transmission of 20% and a crystal length of 50 mm, the maximum CWoutput power of 38.9 W for 81.4 W of incident pump power, corresponding to the slope efficiency of 52.3% and optical-to-optical conversion efficiency of 47.8% (determined with respect to the incident pump power) was achieved. The highest opti- cal-to-optical conversion efficiency of 70.2% with respect to the absorbed pump power was obtained. The influence of a heat-sink cooling water temperature on theCWlaser performance was studied. For a Q-switched operation the pulse repe- tition frequency (PRF) was changed from 2 to 10 kHz. The maximum average output power of 34.1 W at the PRF of 10 kHz was obtained for a 50 mm holmium crystal length. For 2 kHz PRF and 71.9 W of incident pump power, pulse energies of 13.7 mJ with a 21 ns FWHM pulse width corresponding to 652 kW peak power were recorded.