Distributed feedback laser action in reflection geometry from a dye-doped polymer film

Abstract Rhodamine 6G doped poly(methyl methacrylate) thin films were prepared on glass substrates. Tuneable distributed feedback (DFB) lasing output in a reflection grating geometry was realized in the films. Pure gain coupling and an additional index coupling were created in the films by the two crossing pump beams. Under low pump energy, a permanent gain modulation caused by dye bleaching was generated. An index modulation of the medium caused by photodamage was induced at higher pump energy. Dual-peak DFB lasing emission indicative of the existence of the index grating was observed under these conditions.