Abstract: Silicon photonics has been considered as the most promising platform for on-chip optoelectronic integration. However, it is still a great challenge presently for the study of silicon-based active devices such as silicon-based light source, detectors and modulators. Therefore, an asymmetric Ge/SiGe coupled quantum wells which can be used to realize intensity modulation is proposed and simulated. Firstly, the band structure and wave functions of the asymmetric Ge/SiGe coupled quantum wells is calculated using the 8 band k·p theory model. And then, the absorption spectrums of the asymmetric coupled quantum wells for both TE and TM polarization transmission light are simulated in detail under the electric fields from 0 kV/cm to 60 kV/cm. The simulation results show that for TE polarization, the first absorption edge of the asymmetric coupled quantum wells is about 1449 nm without external electric field. While under the applied electric field of 30 kV/cm, the first absorption edge of the asymmetric coupled quantum wells shifts about 22 nm towards long wavelength direction, which is more remarkable than that of traditional uncoupled quantum wells under the same electric field. Therefore, the proposed asymmetric Ge/SiGe coupled quantum wells is a promising structure for siliconbased intensity modulators to achieve lower operating voltage, higher speed and lower power consumption.

Key words: optoelectronics, intensity modulation, quantum-confined Stark effect, Ge/SiGe quantum wells, asymmetric coupled quantum wells