V. Yu. Khramov

Dynamics of the lasing spectrum of a 3-μm Er:YLF laser with semiconductor pumping

This paper discusses a theoretical and experimental study of lasing in an Er:YLF crystal at four wavelengths of the 3-μm transition with selective pumping by the 0.98-μm radiation of laser diodes. Analytical expressions are obtained that describe the variation of the lasing spectrum of the laser.

The dynamics of the emission spectrum of an Er: YLF laser in the pulsed-periodic operating regime

The lasing of an Er:YLF laser has been theoretically and experimentally investigated at wavelengths 2.66, 2.71, and 2.81μm in the pulsed-periodic regime under selective pumping by laser-diode radiation at 0.98μm. A substantial variation of the delays of the beginning of lasing at the individual wavelengths is observed, depending on the pump-pulse-repetition rate, along with loss of the lasing at wavelengths 2.66 and 2.71μm as the pulse-repetition rate increases.

Pulsed-periodic Ho:YLF lasers: optimization problems

This paper analyzes the prospects of creating high-efficiency, low-frequency (100–1000 Hz) holmium lasers as the pumping source of a parametric radiation converter in the 6–8-μm spectral region for precision surgery. It provides a basis for choosing the optical design of a Ho:YLF-laser prototype with the required radiation parameters: energy per pulse up to 80 mJ at a frequency of 100 Hz and 50 mJ at 1000 Hz, pulse width about 20 ns, and M2≈1.5. The experimental study of the dependence of the absorption and weak-signal gain within wide limits of the pump intensity at various Ho3+ concentrations made it possible to estimate how much the processes of ground-state depletion and reabsorption of Ho crystals contribute to the lasing parameters. Pulsed-periodic Ho:YLF lasers were modeled with intense pumping, for which the inversion varies along the active medium during lasing because of saturation of the pumping, as well as because of periodic population inversion of the lower laser level. Optimization is carried out, taking into account the limitation on the radiation strength of the Ho crystals.

Diode pumped Er:YLF laser with tunable lasing spectrum

This paper presents the results of theoretical and experimental investigations of Er:YLF lasing at wavelengths 2.66, 2.71, and 2.81 um for pulse-periodical diode pumping at wavelength 0.98 um. Considerable change of lasing spectrum with increasing of pulse repetition rate was observed. The new method of tuning lasing spectrum based on this effect was suggested.

Multiwave diode pumped Q-switch ErYLF-laser

The results of theoretical and experimental investigations of spectral and power parameters of diode pumped multiwave Q-switch Er:YLF-laser are presented. The series of giant pulses on 2.66, 2.71, 2.81um wavelengths at peak power up to 100kW and pulse duration 30ns were obtained. The theoretical optimization of laser resonator to improve of laser radiation brightness and beam quality was carried out.

Powerful compact Nd:YAG laser

A compact pulsed Nd:YAG laser with lamp pumping has been developed that generates trains of pulses at wavelengths of 1.064 and 0.532μm. The optical layout of the cavity and the parameters of the gradient output mirror have been optimized to achieve quasi-uniform transverse distribution of the output radiation. The pump regimes are optimized, making it possible to achieve a total energy of the laser radiation of about 1J in a train of four pulses at a repetition rate of 5Hz in the course of a single pump pulse. The small size of the laser (the volume of the laser radiator is about 150cm3) allows it to be successfully used in laser medicine.

Optimizing the action of laser radiation on soft biological tissues

The slow heating of human skin by laser radiation is mathematically modelled. It is shown that blood flow has an effect on the temperature variation of the skin tissues during heating. The wavelength of the laser radiation is optimized for uniform therapeutic heating of subcutaneous structures.

Modeling a solid-state laser with diode pumping and a parametric converter of the radiation frequency

A numerical model of a solid-state single-pulse laser with optical parametric generation has been developed that makes it possible to investigate the spatial and energy characteristics of the parametrically generated radiation, taking into account the diffraction effects of the pump radiation and of the signal and idle waves in the cavity of the optical parametric generator (OPG), as well as the interaction with the pump radiation in the volume of the nonlinear crystal of the OPG. Numerical studies of the spatial and energy characteristics of the radiation of an extracavity OPG excited by the radiation of a single-pulse Nd:YVO4 laser with diode pumping have been carried out. The results of a numerical optimization of the cavity configuration of the OPG that makes it possible to improve the radiance characteristics of the parametrically generated radiation at a wavelength of 1.57μm are presented. The energy characteristics of the parametrically generated radiation are compared for linear and ring structural layouts of the OPG cavities.