RF-excited slab waveguide CO₂ lasers utilising graded phase mirror resonators

Two resonators have been designed, each having one aspheric mirror in combination with a plane output coupler. These designed produce a pseudo 8-channel beam which are either in phase (Resonator 1) or out-of-phase (Resonator 2). The output beam was chosen to be a mixture of a lowest order mode with about 30% of a high order mode added for improving the resonator robustness in the case of Resonator 1, and a pure high order mode in the case of Resonator 2. The designs have been verified using numerical simulation, and then manufactured using diamond milling technology. Experimental tests with a 20 mm wide slab waveguide laser show good agreement between theory, numerical simulation and experimental results. In particular, the resulting laser designs have slow sensitivity to tilting errors as predicted.