Polymer/glass hybrid DC-MZI thermal optical switch for 3D-integrated chips

A directional coupler (DC) Mach–Zehnder interferometer (MZI) thermal optical switch based on a polymer and glass waveguide hybrid for three-dimensional (3D)-integrated chips is demonstrated. The proposed thermal optical switch consists of a polymer waveguide and glass waveguide prepared using an ion-exchange technique. The two waveguide cores can achieve coupling in the vertical direction, improving the integration level on 3D-integrated chips, realizing the complementary advantages of polymer and glass materials. Because of the opposite thermal optical coefficients of polymer and glass materials, and the good stability, low transmission loss and large thermal conductivity of glass material, the device with a low power consumption, small dimensions, fast response time and high extinction ratio can be easily obtained. The optical field coupling between the graded refractive index and step refractive index in 3D directions was simulated. The optimized coupling efficiency is 99.82% with an open-window dimension (w) of 3 μm. The refractive index difference between the diffusion surface center and cladding (Δn) is 0.022. The properties of the DC-MZI thermal optical switch were optimized, achieving a switch power consumption of 5.16 mW, a rising time of 128.8 μs, a falling time of 249.5 μs without an air trench structure, and a switch power consumption of 3.74 mW, a rising time of 140.7 μs, a falling time of 256.3 μs after the etching of an air trench structure with a heating electrode width of 8 μm.