Low-power and high-speed thermo-optic switch using hybrid silica/polymer waveguide structure: design,fabrication and measurement

Response speed and power consumption are improved for a Mach–Zehnder interferometer (MZI) thermo-optic (TO) switch, by using a hybrid silica/polymer waveguide structure and optimizing both the thickness of the silica under cladding and that of the PMMA-GMA upper cladding. Fabrication techniques, including chemical vapor deposition (CVD), spin-coating and wet-etching, are adopted to develop the switch sample. Under 1550?nm wavelength, the driving powers under ON and OFF states are measured to be 0 and 13?mW, respectively, indicating a switching power of 13?mW. The fiber-to-fiber insertion loss under the ON state is 15?dB, the extinction ratio between the ON state and the OFF state is 18.3?dB, and the rise time and fall time are 73.5 and 96.5?µs, respectively. Compared with the TO switches based on Si/SiO₂ or all-polymer waveguide structure, the proposed device possesses both low power consumption and fast response speed, by virtue of the large TO coefficient of the polymer core, thin upper/under claddings and the large thermal conductivity of silica.