Directional lasing oscillation of two-dimensional organic photonic crystal lasers at several photonic band gaps

We fabricated a series of two-dimensional (2D) hexagonal organic photonic-crystal lasers whose lattice constant varies from 0.18 to 0.44 mum, and observed clear lasing oscillation at the four lowest band gap frequencies (M-1, K-2, M-2, and Gamma (1)). We used in-plane beam propagation analysis to clarify the 2D feedback mechanism at each gap frequency, which differs for different gaps. The observed K-1 lasing oscillation is due to coupling of three nonparallel diffracted waves, which has a purely 2D character. This shows that photonic crystal lasers can operate with various feedback essentially different from that of conventional 1D distributed feedback lasers. (C) 2001 American Institute of Physics.