Very compact tunable solid-state laser utilizing a thin-film organic semiconductor

Optically pumped organic semiconductor lasers are fabricated by evaporation of a thin film of tris(8-hydroxyquinoline) aluminum (Alq(3)) molecularly doped with a laser dye on top of a polyester substrate with an embossed grating structure. We achieve low-threshold, longitudinally monomode distributed-feedback laser operation. By varying the film thickness of the organic semiconductor film, we can tune the wavelength of the surface-emitting laser over 44 nm. The low laser threshold allows the use of a very compact all-solid-state pump laser ( approximately 10 cm long). This concept opens up a way to obtain inexpensive lasers that are tunable over the whole visible range.