Acousto-optic modulator using SAW-induced birefringence

Date of Completion

January 2003


Engineering, Electronics and Electrical




We have calculated Surface Acoustic Wave (SAW) induced absorption and refractive index changes in InGaAs-GaAs Multiple Quantum Well structures (MQWs) using a two-dimensional gaussian quadradure method. Our method solves strain-induced birefringence and electric field-induced Stark shift simultaneously. We have investigated the effect of the intrinsic strain and the quantum well width on the SAW induced birefringence. Quantum well enhances the birefringence by enhanced Coulomb effect. Intrinsic strain influences the extent of band mixing in MQWs by SAW induced strain therefore has important effect on birefringence in the acouto-optic modulator. The optimized acousto-optic modulator with properly designed intrinsic strain is almost an order improvement compared to our original device. Our method is generic to all the MQWs that can be described by envelope function method. The calculated results show enhancement of the refractive index change near the bandgap edge in MQWs which is useful in optical modulator and switching devices that utilize birefringence. Simulations are compared with experiment in the 980–1010 nm range. ^