An effective mode selection method for square waveguides is proposed. One has to cut up the waveguide and turn the parts around optical axis. Nearly round fundamental mode is almost indifferent to such asymmetry while the minor modes suffer great losses. The "turn" losses evaluation through the mode overlap integral confirms the method effectiveness. Lasing experiments were performed for an RF-pumped CO2 laser with a folded U-type resonator. To introduce asymmetry, waveguide channels were shifted so that the waveguide end fold mirrors image is turned axially.The laser beam quality was tested with "ModeMaster" coherent beam propagation analyzer. M2 value equal to one within the device tolerance is measured.

No abstract

New method based on techniques of self-induced autodyne effect for diagnostics and control of laser-tissue evaporation b y r adiation o f h igh-frequency p umped w aveguide C 02 laser is developed. This method is used for creation of feed-back for smart CO2 laser surgical system of "Lancet" series. The results of medical testing of the smart laser surgical system are presented.