N.A. Ignatov - Employee, PJSC «NPO Almaz» (Moscow). E-mail: ignatovnicita@mail.ru M.A. Ogar - Employee, PJSC «NPO Almaz» (Moscow). E-mail: mogar@inbox.ru A.P. Mineev - Ph. D. (Phys.-Math.), Senior Research Scientist, Associate Professor, GPI RAS (Moscow). E-mail: mineev@kapella.gpi.ru S.M. Nefedov - Employee, GPI RAS (Moscow). E-mail: nefedov@kapella.gpi.ru

Radiation characteristics of planar waveguide operated in cw and pulse periodic mode carbon monoxide lasers excited by a large-aperture RF discharge at a frequency of 40 MHz without gas flow and diffusion cooling of the active medium have been studied [1−5]. Three new models of planar waveguide CO-laser discharged by low-temperature plasma with different dimensions of the active medium have been designed, constructed and studied. Model А ? (3×40×400mm); model В ? (2,7×38×485mm); model С ? (2,7×40×375 mm). The RF discharged electrodes were cooled with hladon from the self-contained cooling unit or the running water. We used stable and hybrid waveguide-unstable resonators, both positive and negative branches of the stability diagram. The dimen-sional, temporary and spectroscopic radiation characteristics and the gas-discharge parameters of the active medium of CO- lasers are investigated in detail. An average output power of 72 W with an efficiency of ~10% in the spectral range 5,3−6,0 μm at electrodes temperature −80°C has been achieved. It is established that the minimum duration of the CO-laser radiation impulses in the regime of free generation is 100 μs (model A). Is carried out the optimization of output characteristics of CO-lasers (models B and C) at the level of output power to 30 W in the continuous and pulse-periodic operating modes depending on: partial composition and the pressure of the working mixture of gases; the input power and the temperature of the electrode-waveguide structure of RF discharge; a selection of the type (stable and hybrid waveguide-unstable) of optical resonator and coefficient of the transmission of output mirror. It is experimentally determined: the op-timum content of Xe - 20% in the working mixture of gases CO:N2:He:Xe:O2 = 2:2:12:4:0,2; the optimum coefficient of the transmission of output mirror ~6%; the dependence of a change in the output power of a CO-laser on the temperature of the electrodes ~0,2−0,9 W/°C. An output power and conversion efficiency CO-laser has been studied for operation at room temperature of the cooling running water from +8 to +24°C. A cw output power of 18 W with an efficiency of ~ 4,5% at electrodes temperature +8°C has been achieved. The oscillation point of laser with an increase in the temperature of the cooling running water to +24°C is reached and the output laser power ~2 W with efficiency ~1% (model C) is obtained. The relative intensities of the spectral lines of the radiation of laser (maximum intensity to 5,43 μm) depending on composition and pressures of gas, repetition frequency and duration of the pulses of pumping are measured. The numerical simulation of the profile of intensity and value of the phase of the radiation of CO-laser with the hybrid waveguide-unstable resonator is carried out. For the optimization of output characteristics of laser the calculation of losses (waveguide, to the connection with the mirrors, to the transmission of output mirror) in the resonator is executed. The estimate of the magnitudes on the basis of obtained data by two methods [6, 7] is carried out: the unsaturated gain of the active medium of laser ~0,4−0,5 m−1 and of intensity of input power of ~250 W with the assigned input RF power density ~5 W/cm3 and the own losses of the waveguide resonator of ~0,3−0,5%.

 

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8. Mineev A.P., Nefedov S.M., Pashinin P.P. Vysokochastotnyjj planarnyjj SO2-lazer s polnostju metallicheskojj ehlektrodno-volnovodnojj strukturojj i neustojjchivym rezonatorom // Kvantovaja ehlektronika. 2006. T. 36. № 7. S. 656−663.