It is shown theoretically that selective perturbation by electrorefractive effect of the even-order modes in III-V semiconductor multimode interference couplers gives rise to high-performance optical switching. The calculated performance of the proposed switch is 3.4 GHz/Vmm, compared to 0.85 GHz/Vmm for an equivalent Mach-Zehnder interferometer (MZI) switch. The effects of electroabsorption and dimension variations are analyzed to demonstrate the feasibility of the proposed device.
M. P. Earnshaw and D. W. E. Allsopp, "Semiconductor Space Switches Based on Multimode Interference Couplers," J. Lightwave Technol. 20, 643- (2002)