The influence of a phase shift in a channel coupling two unstable-resonator CO2 lasers on the band width of stable phase locking of the laser fields was studied experimentally for the first time. The fraction of the radiation affecting the optical coupling was determined experimentally and found to vary in the range 10-3 - 10-2 for different coupling apertures. The maximum mismatch of the resonator lengths which did not disrupt the coherence amounted to (Delta) L approximately equals (lambda) /20. A method developed for calculating the diffraction made it possible to determine numerically the stable phase locking range of the output radiation from two lasers with unstable resonators. The calculated and experimental parametric dependencies of the phase-locking band width were in qualitative agreement.

The new method of surface acoustic waves generation by moving laser beam is described. The maximum amplitude of the acoustic impulse 2000 nm was reached. 1 .© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The emission spectrum of an atmospheric-pressure electron-beam-controlled CO2 laser with a cryogenically cooled active medium was investigated experimentally and theoretically. Systematic experimental data were obtained on the dynamics of the lasing spectrum of such a laser when the initial temperature of the active mixture was in the range 190–290 K. A theoretical model ensured a satisfactory agreement with the experimental results. The finite rotational relaxation time had to be taken into account to provide a correct description of the dynamics of the emission spectrum of such lasers.

Experiments were carried out demonstrating the possibility of generation of high-power CO2 laser pulses of 40 μs duration emitted as a single rotational line by a system of coupled selective and nonselective resonators. When the laser emitted one rotational line the laser efficiency and divergence were practically the same as for many rotational lines. An anisotropy of the radiation divergence was noted in the presence of high-velocity flow of the active medium.

The influence of a phase shift in a channel coupling two unstable-resonator CO2 lasers on the band width of stable phase locking of the laser fields was studied experimentally for the first time. The fraction of the radiation effecting the optical coupling was determined experimentally and found to vary in the range 10 − 3–10 − 2 for different coupling apertures. The maximum mismatch of the resonator lengths which did not disrupt the coherence amounted to ΔL≈λ / 20. A method developed for calculating the diffraction made it possible to determine numerically the stable phase locking range of the output radiation from two lasers with unstable resonators. The calculated and experimental parametric dependences of the phase-locking band width were in qualitative agreement.

Phase locking of waveguide CO2 lasers as a result of a four-wave interaction of lightbeams in an absorbing liquidA. V. Bondarenko, A. F. Glova, F. V. Lebedev, V. V. Likhanskii, A. P. Napartovich,V. D. Pis'mennyi, and V. P. YartsevI. V. Kurchatov Institute of Atomic Energy, Moscow(Submitted January 15, 1988)Kvantovaya Elektron. (Moscow) 15, 877-878 (May 1988)Radiation from two quasi-cw waveguide CO2 lasers was phase-locked by a four-wave mirror. Thecoefficient of coupling between the lasers was determined.

Efficient (49 ± 5%) second harmonic generation was demonstrated for the first time in the infrared. The frequency of CO2 laser radiation with a pulse duration of ~2 nsec and an intensity of up to 1GW/cm2 was doubled in an unbleached ZnGeP2 crystal. The internal energy efficiency was ∼80%.

This communication is the first report of the simultaneous measurement and quantitative theoretical investigation of gains in vibration-rotation transitions of CO and CO/sub 2/ molecules with pumping by an externally sustained discharge. The experiments were carried out on an uncooled atmospheric-pressure electroionization laser. An analysis of the experimental conditions described above and the characteristic times for the establishment of quasi-equilibrium vibrational distribution functions in the modes of CO/sub 2/ showed that it is sufficient to use the harmonic oscillator model to describe CO/sub 2/ molecules. Measurements and calculations of the lasing characteristics were carried out. It was discovered that an addition of carbon dioxide can lower the efficiency to lasing in a CO transition by several fold, while the reverse influence is insignificant.

Experimental and theoretical investigations were made of the processes of drilling and deep melting of metals by pulsed and pulse-periodic laser radiation. Direct photography of the surface revealed molten metal splashing due to interaction with single CO2 laser pulses. A proposed thermohydrodynamic model was used to account for the experimental results and to calculate the optimal parameters of pulse-periodic radiation needed for deep melting. The melt splashing processes were simulated numerically.