Modulation doped SiGe-Si MQW for low-voltage high-speed modulators at 1.3 μm

We propose a new type of light modulator at 1.3 and 1.55 /spl mu/m using a /spl delta/-modulation-doped SiGe-Si multiple-quantum-well quantum-well structure (/spl delta/-MDMQW) integrated in a low-loss silicon-on-insulator (SOI) waveguide, The structure is embedded in the intrinsic region of a vertical p-i-n diode realized on SOI substrate. We present theoretical calculation of the effective index modulation determined by the variation of the confined hole concentration with an applied external field. A practical device is proposed and a calculation of optical modulation efficiency is presented. Estimation of on-off switching time based on evaluation of characteristic time of emission from localized levels in quantum wells and RC characteristics of the device are presented. This device presents the advantage of a broad optical bandwidth in comparison to the modulators based on quantum-defined Stark effect, low insertion loss, high-speed (above 1 GHz), and full compatibility with silicon technology.