SOI (silicon-on-insulator) is a new material with a lot of important perform- ances such as large index difference, low transmission loss. Fabrication processes for SOI based optoelectronic devices are compatible with conventional IC processes. Having the potential of OEIC monolithic integration, SOI based optoelectronic devices have shown many good characteristics and become more and more attractive recently. In this paper, the recent progresses of SOI waveguide devices in our research group are presented. By highly effective numerical simulation, the single mode conditions for SOI rib waveguides with rectangular and trapezoidal cross-section were accurately investigated. Using both chemical anisotropic wet etching and plasma dry etching techniques, SOI single mode rib waveguide, MMI coupler, VOA (variable optical attenuator), 2×2 thermal-optical switch were successfully designed and fabricated. Based on these, 4×4 and 8×8 SOI optical waveguide integrated switch matrixes are demonstrated for the first time.
The hole subband structures and effective masses of tensile strained Si/Si1yGey quantum wells are calculated by using the 6×6 k·p method.The results show that when the tensile strain is induced in the quantum well,the light-hole state becomes the ground state,and the light hole effective masses in the growth direction are strongly reduced while the in-plane effective masses are considerable.Quantitative calculation of the valence intersubband transition between two light hole states in a 7nm tensile strained Si/Si0.55Ge0.45 quantum well grown on a relaxed Si0.5Ge0.5(100) substrates shows a large absorption coefficient of 8400 cm-1.
