Planar CO- and CO2-lasers with an unstable cavity and additional feedback

The radiation of planar RF-excited CO- and CO
2
-lasers with an unstable resonator and one coupling element is spatially superimposed. The divergence and emission spectrum are investigated. It is shown that in CO- and CO
2
-lasers it is possible, by acting on the peripheral part of the composite resonator, to increase the output power and lower the lasing threshold.