Semiconductor space switches based on multimode interference couplers

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.

I. Introduction

Optical switches are of growing importance for routing and other functions in fiber networks. Performance requirements for switches are inevitably system dependent, but include low levels of crosstalk and insertion loss and, often, polarization independent operation. Switch arrays, up to 16 × 16, exploiting the thermooptic effect in silica-on-silicon material can achieve these requirements [1]. However, the switching speed of these devices is limited to a few milliseconds and power consumption is excessive (50 W). Although relatively slow channel allocation times are acceptable for some applications, switching matrices must be reconfigurable in nanoseconds, or faster, for packet-switching applications in advanced optical systems.