RF-Excited Slab Waveguide CO2 Lasers Utilising Graded Phase Mirror Resonators

RF discharge excited slab-waveguide carbon dioxide lasers have been developed as relatively inexpensive sources of good beam quality, high power, far infrared radiation (10.6µm). They commonly incorporate a hybrid resonator design which involves waveguide propagation in the transverse direction and a confocal-unstable design in the lateral (wide) dimension. Such resonators offer excellent beam quality, adequate for most applications. However, they may exhibit variations in the beam shape when mirrors are tilted, and scaling the laser to high powers requires use of wide spherical mirrors, which causes increased sensitivity to unwanted spherical curvatures (bending and twisting) overlaid on the mirror shape during manufacturing and/or mounting, To remove this unwanted behaviour, alternative resonator geometries are under consideration.