High-Speed and Low-Power 2 x 2 Thermo-Optic Switch Based on Dual Silicon Topological Nanobeam Cavities

A 2 x 2 thermo-optic (TO) switch using dual topological photonic crystal nanobeam (PCN) cavities on the silicon-on-insulator (SOI) platform is proposed and experimentally demonstrated. A Fano resonance is observed due to the interference between the topological interface state of the 1D topological PCN cavity and the Fabry-Perot (F-P) cavity mode formed between the two facets of the finitely long nanobeam waveguide. Thanks to the sharp rising edge of the spectral response of the Fano resonance and the high confinement of light in the topological PCN cavities, a 2 x 2 TO switch is realized with short switching time and low power consumption. The measured switching power is only 1.55 mW, and the rising time and the falling time are 3 and 5.6 mu s, respectively in the on-off switching experiments. To the best of the knowledge, this is the first time that a dual topological PCN structure is utilized to realize a high-speed and low-power TO switch, revealing the possibility of designing high-performance reconfigurable optical devices and networks using topological photonics.