Wide-aperture optical resonator with a periodic boundary

An experimental investigation was made of the angular distribution of the radiation emitted from an optical resonator with a periodic boundary. Single-mode lasing was achieved in the case of a wide-aperture He–Ne laser emitting at λ = 3.39 μm and utilizing a resonator with a periodic boundary. The width of this angular distribution was several times less than that obtained for the same laser, but with a resonator formed by two plane mirrors and the divergence was close to the diffraction limit.