Ultralow power silicon photonics thermo-optic switch with suspended phase arms

In this letter, a 2 × 2 thermo-optic waveguide-based switch with ultralow power consumption is demonstrated and fabricated using a standard complementary metaloxidesemiconductor (CMOS) process. The phase arms are suspended by removing adjacent SiO₂ and 120 μm of the underlying Si, while leaving a few SiO₂ beams to support the suspended phase arms for the purpose of structural strength. As compared to the switch without isolation layer, a significant reduction of >98% in power consumption is achieved. It is realized by preventing the heat from leaking out of the phase arms due to the presence of the air isolation layer. Our device shows an extinction ratio of over 23 dB at 1550 nm for TE mode with an ultralow power consumption of 0.49 mW. The response time is 266 μs, including the raise time of 144 μs and the fall time of 122 μs.