Compact 1 × N thermo-optic switches based on silicon photonic wire waveguides

Using silicon photonic wire waveguides, we constructed compact 1 x 1, 1 x 2, and 1 x 4 Mach-Zehnder interferometer type optical switches on a silicon-on-insulator substrate and demonstrated their switching operations through the thermo-optic effect. These switches were smaller than 140 x 65, 85 x 30, and 190 x 75 mum, respectively. At a 1550-nm wavelength, we obtained an extinction ratio larger than 30 dB, a switching power as low as 90 mW, and a switching response time of less than 100 mus. Furthermore, switching operations were successfully demonstrated for the 1 x 4 switch.