The Study Of An In InGaAsP/InP 3×3 Multimode Interference Electro-optic Switch

As fiber-optic communication technology has developed rapidly, optical switches play important roles in data links of optical communication systems. In recent years, various approaches realizing optical switches have been proposed, including mechanical optical switch, MEMS-based optical switch, and optical waveguide switch. Waveguide based photonic switch shows the great promising in fast response speed, compact sizes, and performance stability. Different waveguide-based optical switches are proposed so far, such as optical directional coupler switch, multimode interference(MMI) type,and Mach-Zehnder interferometer(MZI) optical switch. Among them, MMI switches exhibit better performance with low insertion loss, broad bandwidth, and simple fabrication process.MMI photonic switch usually adopts electro-optic effect or thermal-optic effect. The switching speed of thermal-optic type is slow, generally in the μs level. Regarding electro-optic effect, the index modulation of carrier injection on III-V semiconductors is used here, its switching speed can be enhanced significantly. Recently MMI optical switch based on GaAs, InP, Ⅲ- Ⅴ semiconductor materials have attracted more attention due to high switching speed.In this thesis, an InGaAsP/InP 3×3 multimode interference electro-optic switch has been demonstrated. Firstly, the principle of self-imaging effect is analyzed theoretically. Towards optimizing the device parameters, single mode ridge waveguide with proper width and height, sizes of multimode waveguide region is designed using a FD-BPM simulation method. Secondly, the switching voltage to the index modulation region is determined by Silvaco software. The 9 switching states and their corresponding performance of the device can be achieved. The simulated results show that the device exhibits the low crosstalk less than-22 dB and the insertion loss as low as ~0.12 dB.The standard semiconductor processing steps are utilized to fabricate the optimized structure of the device. Because the device sizes should be made accurately,this increases the challenging of an operational device. Lastly the device is measured by using an end-fire coupling setup. The proposed 3×3 MMI electro-optic switch provides a potential application for on-chip optical interconnect, and the device may serve as a building block forming a future large-scale switch matrix.