Waveguide CO2 laser with a selector utilizing a lens and tunable in a frequency band exceeding the resonator intermode spacing

Theoretical and experimental investigations were made of waveguide CO₂ laser resonators in which different variants of a reflecting interferometer with a diffraction selector were used. A reflecting interferometer, combining a diffraction selector and a diffraction grating, was proposed and realized. Its use provided not only line selection in the waveguide CO₂ laser, but also selection of a required longitudinal resonator mode within the gain profile of a given line. More than 30 lines due to the 00⁰1–[10⁰0, 02⁰0] transitions were selected. Waveguide laser operation was obtained for the first time for sequence transitions, in the P-branch lines of the 00⁰2–10⁰1 transition. Continuous tuning was realized in a frequency range exceeding c / 2L = 390 MHz. The tuning band, bounded by the part of the gain profile above the threshold level, was ~ 800 MHz. A power density of 500 W/cm² incident on the selector did not change its characteristics. The proposed configuration was shown to have advantages over the known resonator schemes. These are an increased selectivity, smaller overall dimensions, and simplicity of realizing power-optimized decoupling.