Thin-film laser with a two-dimensional diffraction grating

Single-frequency stimulated emission (λ = 635 nm, line width 0.3 nm) was obtained from a laser utilizing a dye-activated single-mode planar waveguide. Distributed feedback was provided by a rectangular grating having a pitch of 0.433μ along both coordinates located on the waveguide surface. This grating was used to extract the radiation along the normal to the waveguide plane. Using this structure, it was possible to achieve extremely low radiation divergence (~20' × 20') since the total surface of the excited waveguide section emitted coherently (the area of the excited section was approximately 1 mm 2 ). The use of different types of two-dimensional gratings in similar structures is discussed.