Thin-film waveguide laser with a distributed feedback and gain modulation

Laser action was produced in a polymethylmethacrylate film activated with rhodamine 6F and deposited on a quartz substrate. The film was pumped with two converging second-harmonic neodymium laser beams, which formed an interference pattern. The rectangular edge of the quartz substrate acted also as a beam splitter of the pumping radiation. The output frequency of the film laser was tuned by altering the angle which the quartz plate made with the direction of the pumping radiation.