Optical switch fabric design for large fabrication tolerance

Optical cross-connect switches (OXC) are key components in advanced WDM networks. Integrated optical switches have been reported using several mechanisms and materials. We have demonstrated waveguide-type thermo-optic switches which employ silica-based planar lightwave circuits. The crosstalk of OXC, due to a number of reasons, is an important parameter which influences the system performance. One of the reasons is the coupling ratio (CR) of a 3 dB coupler in a switch unit. Due to fabrication limitations, it is hard to obtain the exact CR as designed. We propose a scheme to achieve low crosstalk even with variation of CR. The design of our optical switch fabric is a strictly non-blocking matrix switch using dilated double-layer architecture.