Abstract
Abstract
We developed a compact thermo-optic Mach–Zehnder interferometer switch with a direct heating heater using multimode interference and achieved a sufficiently low thermal crosstalk performance. Large-scale switch systems, such as optical neural networks, require thermo-optical switches with low power consumption, fast switching speed, compact size, and low thermal crosstalk. This switch is equipped with a heater that directly heats the Si core waveguide, which is a structure that connects non-doped Si wires between phase shifters and a heatsink. As a result, a significant miniaturization with a phase shifter length of approximately 7 μm, low π-phase shift power consumption of less than 20 mW, and fast switching in sub-microseconds were achieved. The improved phase shifter showed a very small figure of merit of 8.89 mW∙μs. Simultaneously, transmission spectrum measurements of nearby ring resonators show that the thermal crosstalk is significantly reduced even at a distance of only 30 μm. This device can contribute to the overall circuit performance and footprint reduction in large-scale optical integrated circuits and optical neural network configurations.