Effects of duty cycle on the characteristics of a composite surface-emitting organic distributed feedback laser

[[abstract]]Based on the coupled-wave theory, we model the periodic structure and analyze the influence on composite surface-emitting organic distributed feedback (DFB) lasers. Second-order DFB gratings with duty cycles of 0.3, 0.5, and 0.7 patterned by electron-beam lithography were fabricated. The composite active layer consisted of 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) and poly(N-vinylcarbazole) (PVK) spin-cast on a textured surface. Excited with 532 nm laser pulses, different lasing characteristics and threshold pumping fluences are exhibited. These are explained by the discrepancy in the coupling coefficients and the threshold gains calculated from the proposed model.[[fileno]]2010124010011[[department]]物理