Interdiffusion induced modification of surface-acoustic-waveAlGaAs-GaAs quantum-well modulators

摘要

A theoretical study of short period AlGaAs-GaAs diffusednquantum-well (QW) absorption modulators operated by using surfacenacoustic waves (SAWs) is carried out in this paper. The as-grown QWnstructure is optimized and interdiffusion is used to fine tune thenmodulation performance. The results show that a stack of QWs can bendeveloped at the top surface of the modulator to utilize the steepnpotential induced by SAWs. The optimized structure can also produce anlarge absorption change and thus a fast modulation speed for the samenmodulation depth. In comparison to previous results, the requirednsurface acoustic wave has a longer wavelength and a lower power so thatnthe fabrication of the interdigital transducer can be simplified. Innaddition, the use of interdiffusion can provide an useful finenadjustment to the operating wavelength, further enhancement of thenmodulation depth and an improvement in chirping with the only drawbacknof an increased absorption loss