Schematic cross sections of MOS high-index-contrast SOI rib waveguides for 1.55 μm wavelength. Three doping schemes are shown: (a) for inversion, (b) for accumulation, and (c) for depletion operation.
Steady-state effective refractive index variation of the TE-like fundamental mode as a function of the absolute voltage of the gate voltage for inversion (squares), accumulation (circles), and depletion (triangles) operation modes for gate oxide thicknesses of (a) and (b) . The applied voltage is negative for the inversion and accumulation modes and positive for the depletion mode.
Steady-state carrier 2D distribution in the Si core waveguide for the depletion-mode operation. The gate voltage is and . Strong inversion condition is observed (electron inversion layer beneath the gate oxide).
Optical losses of the TE-like fundamental mode as a function of the absolute value of the gate voltage for inversion (squares), accumulation (circles), and depletion (triangles) operation modes for gate oxide thicknesses of and .
TE-like fundamental optical mode profile for (a) and (b) .
Effective refractive index variation of the TE-like fundamental mode as a function of the absolute value of the ON-state gate voltage for depletion mode under pulse (triangles) and dc (circles) operation and for the accumulation mode (squares). (b) Optical losses for the same configurations. Dashed lines indicate that the Si breakdown electric field has been exceeded. The gate oxide thickness is . The applied voltage is negative for the accumulation case and positive for the depletion mode.
High-index-contrast waveguide electro-optic modulator based on a microring resonator and a MOS diode. The complex refractive index of the resonant region is changed by applying a bias voltage to the gate electrode.
Spectral transmittance (out port) for the TE-like fundamental optical mode of the simulated electro-optic MOS Si microring modulator (accumulation configuration) for (OFF state) and (, ON state) for a ring radius of . The circles illustrate the modulation depth at .
Calculated modulation depth of the electro-optic MOS microring resonator for the accumulation (squares) and depletion (circles) modes. TE-like fundamental mode is considered. The dashed line indicates that the Si breakdown electric field has been exceeded. The probe wavelengths are 1550.014 nm and 1549.975 nm for the accumulation and depletion cases, respectively. The transmittivity in the OFF state at the corresponding probe wavelength was calculated to be 59% and 23% for the accumulation and depletion cases, respectively.
Main parameters used in the simulations at 300 K.
Switching times of the MOS waveguide under accumulation and depletion regimes for different gate voltages. is positive for depletion and negative for accumulation.
All-silicon electro-optic modulators recently proposed in the literature .
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