Photopumped Organic Solid-State Dye Laser with a Second-Order Distributed Feedback Cavity

We describe a photopumped distributed feedback (DFB) organic solid-state dye laser consisting of an active layer containing a low-threshold gain-narrowing dye and an SiO2 DFB cavity based on second-order diffraction. A second-order diffraction grating is easy to fabricate compared with a first-order one having the same Bragg wavelength. When 4,4'-bis(4-(ditolyamino)styryl)biphenyl was used as the laser material, the threshold of the laser was 0.8 kW/cm2, a low value despite using a low-coupling-coefficient cavity based on second-order diffraction. This was a result of using a low-threshold gain-narrowing dye. Laser-light emission from the surface was observed, indicating that an organic "transverse cavity" surface-emitting laser could be developed using a second-order diffraction grating and a low-threshold gain-narrowing dye.