Linear and Nonlinear Intersubband Optical Absorptions and Refractive Index Changes in InGaN Strained Single Quantum Wells: Strong Built-in

Considering the strong built-in electric field (BEF) effects due to the spontaneous and piezoelectric polarizations, the intersubband optical absorptions and refractive index changes for an In_xGa_1-xN/Al_yGa_1-yN strained single quantum well are studied theoretically within the framework of the density matrix method and effective-mass approximation. The linear, third-order nonlinear and total absorption coefficients and refractive index
changes are calculated as a function of the incident optical intensity and photon energy. Our results show that both the incident optical intensity and the strong BEF have great influence on the total absorptions and refractive index changes. The results are significant for designing some important photodetectors and the photonic crystal devices with adjustable photonic band structures.