A study was carried out by means of computer simulation of solar-to-laser-power conversion process using Monte-Carlo ray-tracing methods in solar concentrators with spot sizes exceeding the transverse dimensions of commonly used active media by several or more times. It is shown that, in such cases, the use of one active medium for pumping does not allow achieving high conversion efficiency, and in this connection, a new multi-rod system is proposed, which makes it possible to increase the efficiency by several times.

We investigated the luminescence intensity of a Nd 3+ :Y3Al 3 O 12 laser crystal excited by the radiation of a blue LED with λ » 454 нм, simulating the ultraviolet part of the solar spectrum, before and after using of a spectral converter based on the Ce 3+ : Y 3 Al 3 O 12 phosphor. It was found that while we used such a phosphor, the luminescence intensity of Nd 3+ : Y 3 Al 3 O 12 at λ » 1064 nm was approximately three times higher than without it. Thus, yttrium-aluminum garnet crystals doped with cerium ions are promising luminophores for the introduction in quanthrons of solar-pumped neodymium lasers for increasing their efficiency.

The luminescence intensity of a Nd3+:Y3Al5O12 laser crystal excited by light from a blue LED with λ ≈ 454 nm, simulating the ultraviolet part of the solar spectrum, is studied before and after use of a special converter based on Ce3+:Y3Al5O12 luminophore. It is found that when this type of luminophore was used, the intensity of the luminosity of the Nd3+:Y3Al5O12 at λ ≈ 1064 nm was ~3 times greater than without it. Thus, cerium–ion doped yttrium–aluminum garnet crystals offer promise as luminophores in the heads of solar-pumped neodymium lasers for raising their efficiency.

The study of the process of energy transfer in an active medium with a sensitizer based on Ce: Nd: YAG material under pumping by LED at a wavelength of 454 nm and by solar radiation is carried out. Based on the results of experimental studies of the energy transfer process with blue LED excitation, it was determined that the overall efficiency of energy transfer from Ce ions to active Nd ions in a Ce: Nd: YAG laser rod is similar to 76%. The conducted comparative studies of Nd: YAG and Ce: Nd: YAG luminescence with the excitation by solar radiation has shown 1.5 fold increase of Nd luminescence in Ce:Nd:YAG which means that the threshold power of Ce:Nd:YAG solar lasers can be reduced by 1.5 times. At the same time, the pumping efficiency is increased by the same factor compared to Nd:YAG solar laser. Thus, under the same pumping conditions, the output power of Ce:Nd:YAG solar laser can reach two fold increase compared to Nd:YAG solar laser. Our study confirms that Ce: Nd: YAG is one of the best alternatives to Nd: YAG in solar pumped lasers.

The effect of using external frequency converters on the luminescence intensity of an Nd:YAG crystal is studied. The crystal is illuminated by light-emitting diode (LED) with and without Y3Al5O12:Ce3+ material as an external converter. Obtained experimental results show that the luminescence intensity of Nd:YAG crystal increased by 1.5 times when Nd:YAG crystal is illuminated by LED together with color converter based on Y3Al5O12:Ce3+ demonstrating that external frequency converters can be a potential candidate for creating more efficient solar or LED pumped lasers.

Прозрачные керамические YAG-лазерные материалы с высоким содержанием неодима исследуются для применения в преобразовании солнечной энергии в энергию лазерного излучения с помощью метода имитации трассировки лучей Монте-Карло. Показано, что использование высоколегированных керамических Nd:YAG-лазерных материалов в дисковых лазерах с солнечной накачкой повышает эффективность преобразования солнечной энергии в лазерную по сравнению с обычно используемым 1% ат Nd:YAG.

Simple approach for achieving high efficiency of solar pumped laser performance on the base of alexandrite active medium is proposed. Performance analyses have been conducted by simulating solar pumped alexandrite laser with core-doped parabolic shape composite active medium, using ray-tracing Monte-Carlo techniques. It is shown that the overall efficiency of alexandrite laser can be about 15% which is much higher than that of existing solar pumped lasers.

The new multi-pass configuration of side-pumped Nd:YAG solar laser for enhancement of conversion efficiency is studied by computer simulation of the laser system. The active medium in the form of a slab providing effective heat dissipation during side pumping by concentrated solar radiation at the focus of a parabolic concentrator with a diameter of 1 m is considered. It is shown that multi-pass configuration doubles the output laser power.

The possibility of achieving high efficiency of converting solar energy into laser radiation energy on the basis of the active element Nd: Cr: GSGG in the form of a thin slab allowing providing an effective heat output during side pumping by concentrated solar radiation at the focus of a parabolic concentrator with a diameter of 1 m2 is considered. The study was carried out by computer simulation of the laser system.

On the basis of the active element of Ti3+:Al2O3, the possibility of converting solar energy into laser radiation energy is investigated. By the computer simulations, it was shown the possibility of reducing the threshold pump power by choosing the optimal geometry of the crystal parameters for end-pumping scheme of concentrated solar radiation.

A simulation model for a solar laser is designed using Ce:Nd:YAG as an active medium. A system of a parabolic concentrator, a glass light guide and a secondary concentrator is simulated to concentrate the solar radiation on to a laser head of the type Ce:Nd:YAG. The results show that adding Ce to the Nd:YAG increases the slope efficiency of this laser. Accordingly, an increase of the output laser power by a factor of about two is obtained.

The possibility of increase of Nd:YAG solar pumped lasers pumping efficiency with the use of Cr:LiCAF as a solar spectrum frequency-down-shifting element is studied by the simulation calculation method. Comparative analyses of side- and end-pumping schemes are conducted. The numerical experiments have been conducted for combinations of Nd:YAG active medium and Cr:LiCAF for both side- and end-pumping configurations. It is shown that the use of Cr:LiCAF frequency down-shifter significantly increases the pumping efficiency of Nd:YAG active medium in both cases. In addition the replacement of Nd:YAG with cerium co-doped Nd:YAG have shown possibility of further increase the efficiency.

A new approach based on the use of external frequency converters for Nd:YAG solar pumped lasers providing effective conversion of solar-to-laser power is proposed. The possibility of a more than four-fold increase in Nd:YAG solar pumped laser efficiency is shown by the simulation calculation method.

The new type of high efficiency solar pumped laser based on the active element of Nd:Cr:GSGG in the form of a thin slab with side pumping by concentrated solar radiation at the focus of parabolic concentrator with a diameter of 1 m2 is studied by computer simulation method. The solar pumped laser (SPL) is a device that converts the solar radiation energy into the laser light energy. The SPLs use different active mediums that absorb the solar light and transform it into the laser light. The main problem of SPLs today is low efficiency. The maximal efficiency achieved is 30W/m2 which is less than 5 % with the use of Nd: YAG (Neodymium doped Yttrium Aluminum Garnet, chemical formula Nd:Y3Al5O12). Therefore in this work we propose to use active element of Nd:Cr: GSGG (Neodymium and Chromium codoped Gallium Scandium Gadolinium Garnet ) to increase the efficiency.