A. P. Pogoda

All-solid-state Nd: YAG lasers with self-pumped multiwave-mixing phase conjugate cavities

Several configurations of the laser self-pumped phase-conjugate cavities with multiwave mixing directly in the laser medium based on a single Nd:YAG laser element pumped by multikilowatt laser diode 2D stacks are experimentally studied and compared. In the laser configurations with six- and eight-wave mixing there are generated a high-intensive self-Q-switched 200-ns laser pulse followed by low-intensive free-running lasing. An increase of the number of waves taking part in multiwave mixing from six to eight leads to increase in the laser maximum output energy and optical-to-optical efficiency from 0.55 up to 1.1 J and from 8.3 up to 18% respectively. In the laser configuration with ten-wave mixing the energy characteristic is similar to the same in the laser configuration with eight-wave mixing, but the temporal and spectral characteristics are different from the same in the laser configurations with six- and eight-wave mixing. In last laser configuration not only the first pulse, but also all the train of pulses is generated in high-intensive TEM00 diffraction-limited (M2 = 1.3–1.5) single-frequency self-Q-switched mode via writing and erasing the gain gratings by the intracavity radiation.

High power Nd:YAG laser with self-pumped phase-conjugate loop cavity and repetitive pulsed diode-matrix side-pumping

The joule-range high-beam-quality Nd3+:YAG laser oscillation in the multiloop self-pumped phase-conjugate cavity without an output coupling mirror at four-wave mixing of intracavity beams directly in the 110-mm long Nd3+:YAG rod with 12.6 kW diode side-pumping is developed and studied. The oscillation efficiency of up to 18 % and average power of up to 22 W were achieved in the optimized geometry of the laser cavity at the 13.9 kW pumping with repetition rate of up to 20 Hz and pulse duration of up to 475 μs. The laser generated a single high-intensive 200-ns giant laser pulse (or series of such pulses with microsecond period at increased pumping) oscillated at self-Q-switch on gain gratings with relatively narrow linewidth of about 2 GHz followed by low-intensive free-running wideband lasing. We also realized a passive Q-switch by the F2-:LiF and Cr4+:YAG crystals with oscillation of pulse trains and also 30-ns single-pulse oscillation with an individual pulse energy of up to 60 mJ and peak power of up to 4 MW at narrowed laser spectra down to 1.7 GHz.

Generation regimes of a pulsed Nd:YAG laser with transverse LED pumping and multiloop self-pumped phase-conjugate cavity

The generation regimes in a pulsed Nd:YAG laser with transverse LED pumping and multiloop self-pumped phase-conjugate cavity on the gain gratings are studied. The differential efficiency of laser is 27% in the free-running regime at a pulse energy of up to 1 J and quality parameter M2 of no greater than 1.5. The pulse energy under passive Q-switching is no less than 60% of the pulse energy in the free-running regime at the same beam quality. The generation of the narrow-band radiation is demonstrated. A generation band of no greater than 1.2 GHz corresponds to the primary single-frequency high-power laser pulse in the free-running mode under conditions for self-Q-switching on the gain gratings. When additional elements (F2−:LiF and Cr4+:YAG crystals) are introduced in the optical scheme of the phase-conjugate cavity, similar narrowband single-mode generation is observed in the passive Q-switching regime as a pulse train or monopulse. The laser pulse power is up to 2 MW at a pulse duration of 20 ns.

The passive Q-switching regime in a solid state laser with a multiloop cavity

A compact, pulsed-periodic YAG: Nd3+ laser with self-pumped phase-conjugate multiloop cavity and passive Q-switching by YAG: Cr4+ and GSGG: Cr4+ crystals has been studied. It is established that the energy and temporal parameters of radiation in separate pulses of a periodic train can be controlled almost without changing the pulse train energy. A regime of generating modulated radiation pulses with a peak power of up to 30 MW and a spatial brightness of 1.7 × 1015 W/(cm2 sr) at a radiation beam quality parameter of M2 < 1.2 has been realized in experiment.

Holographic self-Q-switching of Nd:YAG all-solid-state lasers with Cr:YAG saturable absorber

The study of the generation characteristics of Nd:YAG lasers with multiloop self-organizing phase conjugate cavities using a passive Q-switch based on a Cr:YAG crystal is carried out. It is shown that Q-switching of the phase conjugate cavity is caused not only by absorption saturation of the passive Q-switch, but also by modulation of diffraction efficiency of holographic saturable gain gratings in the Nd:YAG active laser medium.

All-solid-state laser system with coherent combining of independent channels via common laser beam

The multichannel laser system with coherent combining as a result of fourwave mixing in active laser media is proposed.

Principles of influence on the spectral properties of solid-state laser with loop cavity

Principles of spectral narrowing of radiation of laser with loop cavity due to phase conjugation phenomenon are discussed. The gain gratings in active media results in competition in longitudinal modes and spectral selectivity.

High-energy compact-size diode-pumped Nd:YAG laser with self-pumped phase-conjugate dynamic cavity

Compact-size, multiloop, self-phase-conjugated Nd:YAG laser pumped by 4D diode stacks was studied. The use of a passive LiF:F2-Q-switch resulted in pulse train oscillation depending on the passive Q-switch position and length of diffractive feedback in the cavity. The laser energy of up to 2.55 J in trains of 13 pulses with 11-ns duration was obtained.

Compact transversely diode-pumped Nd:YAG laser with a self-pumped phase-conjugate multiloop cavity

A compact high-power repetitively pulsed Nd :YAG laser with transverse diode pumping and a multiloop self-pumped phase-conjugate cavity is presented. The obtained pulse trains have an energy of with beam quality , a divergence of , and a spatial brightness of . The peak power of single-frequency pulses exceeds at a pulse energy of . The laser bandwidth is .