Ultra-compact silicon photonics switch with high-density thermo-optic heaters

Miniaturization of silicon photonics switches is essential for both dense integration and low-loss operation. However, it has remained unclear how small the switches can be made while using thermo-optic (TO) element switches. In this paper, the minimum possible distance between adjacent TO phase shifter arms was first examined. Next, the architecture for a switch matrix for the high-density arrangement of TO switches that includes multi-layer electrical wirings for compact electrical wire-out was proposed and demonstrated. As a result, we achieved 1/23 miniaturization of an 8 × 8 silicon photonics switch for the PIC part when compared with our previous design.