Konstantin V. Mitin

Crystal growth and characterization of new quaternary chalcogenide nonlinear crystals for the mid-IR: BaGa 2 GeS 6 and BaGa 2 GeSe 6

Non-centrosymmetric crystals of BaGa2GeS6 and BaGa2GeSe6 were grown in large sizes with good optical quality, which enabled the characterization of their linear (transmission, dispersion, and birefringence) and nonlinear (second order susceptibility) properties for the first time.

Frequency conversion of multi-line carbon monoxide laser in PbIn 6 Te 10 crystal

Frequency conversion of carbon monoxide laser was for the first time obtained in PbIn6Te10 nonlinear crystal. Laser-induced damage threshold, sum and different frequency generation efficiency under multi-line CO laser pumping were measured.

Optical parametric oscillator on an Hg{sub 1-x}Cd{sub x}Ga{sub 2}S{sub 4} crystal

Lasing was obtained for the first time in an optical parametric oscillator (OPO) on an Hg1-xCdxGa2S4 crystal pumped by a nanosecond Nd:YAG laser. Due to the cadmium concentration gradient along the crystal axis, the OPO could be tuned under noncritical phase-matching conditions by a linear displacement of the crystal. The tuning range was 2.85–3.27 μm, with the maximum slope conversion efficiency equal to 6.6%.Lasing was obtained for the first time in an optical parametric oscillator (OPO) on an Hg{sub 1-x}Cd{sub x}Ga{sub 2}S{sub 4} crystal pumped by a nanosecond Nd:YAG laser. Due to the cadmium concentration gradient along the crystal axis, the OPO could be tuned under noncritical phase-matching conditions by a linear displacement of the crystal. The tuning range was 2.85-3.27 {mu}m, with the maximum slope conversion efficiency equal to 6.6%. (nonlinear optical phenomena)

Low threshold non-linear feedback in CO2 laser resonator

It is shown theoretically, that observed in experiments the strong low threshold feedback in the resonator with a high pressure gas (Xe) cell of the CO2 laser, in which the frequency interval between axial modes is equal to frequency Stokes shift at Stimulated Brillouin Scattering (SBS) in Xe, can arise owing to nondegenerate four-wave mixing in a gas cell on generated as at SBS running phase gratings.

A HgGa{sub 2}S{sub 4} optical parametric oscillator

Parametric generation in a HgGa{sub 2}S{sub 4} crystal pumped by a nanosecond Nd:YAG laser is obtained and investigated for the first time. The experimental results demonstrate the outlook for using HgGa{sub 2}S{sub 4} crystals for the development of efficient optical parametric oscillators in the mid-IR range. (nonlinear optical phenomena and devices)

Nonlinear optical properties of active medium at intracavity phase conjugation of long pulse CO2 laser radiation

Phase conjugation process at intracavity degenerate four wave mixing of a long pulse CO 2 laser radiation in its active medium has been studied experimentally. Dependencies of energetic and temporal characteristics of the phase conjugation signal upon specific energy stored into electric discharge, Q-factor of laser resonator, laser mixture composition and pressure, interaction angle, optical delay between probe and co-propagating waves, intensity ratio for these waves J 3 /J 1 , a degree of inear polarization, and laser spectrum are analyzed. Reflectivity of the phase conjugation signal is shown to increase with specific input energy rise and a decrease of the ratio J 3 /J 1 , being up to 7.5%. An increase of nitrogen content and a decrease of helium content in the laser mixture results in reflectivity rise and peculiar laser pulse profile with two maximums being due to amplitude and phase nonlinearities of the active medium. Specific input energy rise and an increase of Q-factor leads to a decrease of response time for the phase conjugation signal. Nonlinear properties of degenerate four wave mixing on amplitude gain and phase thermal diffraction gratings in the active medium of a long pulse CO 2 laser are analyzed theoretically. An interconnection of nonlinear parameters of the amplifying media with the temporal behavior of phase conjugation reflectivity is determined. A comparison of the theoretical calculations and the experimental data has been done.

Transient four-wave mixing of pulsed CO2 laser radiation in semiconductors

A temporal behavior of a phase conjugation reflectivity R at degenerate four-wave mixing (DFWM) in InSb for a pulsed carbon-dioxide laser radiation is theoretically investigated. It is shown, that R at a transient DFWM is determined by a response time of a nonlinear medium, which depends on intensity of a radiation, and can be some times higher than a reflectivity for non-transient condition.

Degenerate four-wave mixing and phase conjugation of pulsed CO2 laser radiation on transient gratings inside its own inverted medium

Degenerate four-wave mixing (DFWM) and phase conjugation (PC) of pulsed carbon-dioxide laser radiation on transient gratings inside its own laser medium have been studied both experimentally and theoretically. The operational mode of the e-beam controlled discharge carbon-dioxide laser has been chosen in such a way (CO2:N2:He equals 1:2:4, p equals 0.28 atm, tin equals 30 microseconds) that the laser pulse length (tauout approximately 10 - 20 microseconds) is comparable with an effective relaxation time of the upper laser level (taurel approximately 15 - 30 microseconds). The time-history of the carbon-dioxide laser and pc signal pulses, and pc reflectivity have been thoroughly investigated for different cavity Q factors and specific electrical energy inputs. It has been shown, that the formation of the PC signal under the intracavity DFWM on gain (amplitude) and thermal (phase) gratings is characterized by a complicated time history that reflects the main relaxation processes taking place inside the inverted medium. A feature of the transient pc process inside the laser active medium is the dependence of the effective relaxation time of the upper laser level on the intensity of pumping waves. Pc reflectivity has been obtained by numerical calculations. A comparison of the theoretical and experimental data confirms the contribution of two different mechanisms of grating formation under DFWM inside the active medium of the carbon-dioxide laser.

Degenerate four-wave mixing and phase conjugation of pulsed 10-μm laser radiation on transient gratings inside an inverted CO 2 medium

Degenerate four-wave mixing (DFWM) and phase conjugation (PC) of pulsed carbon-dioxide laser radiation on transient gratings inside its own laser medium have been studied both experimentally and theoretically. The operational mode of the e-beam controlled discharge carbon-dioxide laser has been chosen in such a way (CO2:N2:He equals 1:2:4, p equals 0.28 atm, tin equals 30 microseconds) that the laser pulse length ((tau) out approximately equals 10 - 20 microseconds) is comparable with an effective relaxation time of the upper laser level ((tau) rel approximately 15 - 30 microseconds). The time-history of the carbon-dioxide laser and PC signal pulses, and PC reflectivity have been thoroughly investigated for different cavity Q factors and specific electrical energy inputs. It has been shown, that the formation of the PC signal under the intracavity DFWM on gain (amplitude) and thermal (phase) gratings is characterized by a complicated time history that reflects the main relaxation processes taking place inside the inverted medium. A feature of the transient PC process inside the laser active medium is the dependence of the effective relaxation time of the upper laser level on the intensity of pumping waves. PC reflectivity has been obtained by numerical calculations. A comparison of the theoretical and experimental data confirms the contribution of two different mechanisms of grating formation under DFWM inside the active medium of the carbon-dioxide laser.