Threshold behavior of defect modes in one-dimensional active photonic crystal

Based on a model of coupling Maxwell's equations with the rate equations of electronic population, the spatial-distribution and spectrum-characteristics as well as amplified properties of defect modes such as lasing threshold, saturated output in a single-defect active photonic crystal are investigated through finite-difference time-domain method. Influences of the number of crystal periods and spatial profile on amplified feature are also analyzed. The results show that the lasing threshold and saturated output depend directly on the number of crystal periods and the spatial profile of defect modes; the defect mode with lower mode area has a low-threshold. Furthermore, the lasing threshold can be further reduced as the saturated output increases if the number of crystal periods increase. Such a feature is important for understanding of the interaction between optical gain and defect modes.