Figure 1

(a) 3D schematic of the on-chip WDM filters consisting of four cascaded tunable Si-MRRs with different radii. Inset: zoom-in view of microring waveguide with ITiO/HfO₂/Si MOS capacitor. (b) Simulated mode profiles in the active region with waveguide widths of 300 and 400 nm, respectively. (c) Simulated Q-factor (blue) and tunability (orange) versus waveguide widths by assuming that the gate material has a carrier concentration of 3 × 10¹⁹ cm⁻³ and mobility of 25 cm²V⁻¹ s⁻¹ in the simulation. (d) Simulated Q-factor as a function of mobility with different waveguide widths, assuming that the bent Si waveguide has a radius of 8 μm and a height of 250 nm with a 50 nm slab in the simulation.