Design of Silicon Photonic microring resonators with complex waveguide cross-sections and minimal non-linearity

Abstract

We present a model and a rigorous method to calculate the transmission coefficient of silicon micro-rings with complex waveguide cross-section including non-linear effects and self-heating, with very short simulation times. The method is applied to the design of MRRs in the SISCAP platform with high Q and reduced non-linearity, namely due to two photon absorption and free carrier absorption. We demonstrate that the free carrier diffusion in rib waveguides and Shockely-Read-Hall recombination play a fundamental role in reducing the impact of non-linearities in the ring.

Figures (15)

• Figure 1: Sketch of the different nonlinear effects in silicon, involving transitions between the conduction and valence bands.
• Figure 2: Silicon and polysilicon waveguide cross sections considered in this work according to the geometries available in the SISCAP platform.
• Figure 3: The SRH recombination consists of four processes: $r_{ec}$ is the capture of the electron from the conductive band to the trap level, and $g_{ee}$ is the emission of the electron from the trap level to the conductive band. Similarly $r_{hc}$ and $g_{he}$ are respectively the capture and emission of a hole between the trap level and valence band.
• Figure 4: Bend losses as a function of radius for four type of MRRs with different cross-section. Exponential fits of the numerical results are reported with a solid line.
• Figure 5: Example of FC generation rate due to TPA ($G_{ph}(x,y)$) with circulating power equal to $100$ mW in the case of the Si/PolySi 3 wings Rib waveguide.