Stimulated Raman Scattering in Nonlinear Silicon Nanophotonic Waveguides: Theory and Applications in Photonic Integrated Circuits

Photonics caught world attention since channel capacity limit of metallic interconnects approached due to research and design in high speed digital processors. Use of dielectrics, instead, suitable for light propagation was more attractive due to its extremely wide bandwidth. Many of the devices, both active and passive, have been demonstrated using these insulating materials. Due to its excellent optical characteristics, established fabrication history, and cheaper throughput, silicon found its place in photonics arena. However, due to its indirect band structure, efficient light sources are not possible using silicon as the base material. Nevertheless, techniques such as stimulated Raman scattering and third-harmonic generation have made it possible to avoid this natural hurdle in the path of silicon as a light source. This paper reviews basic theory of stimulated Raman scattering, its applications in the context of silicon based photonic integrated circuits and describes ways to improve this nonlinear effect. This paper also covers few of the most important demonstrations of stimulated Raman scattering published in literature from the last decade.

Confinement Specific Design of SOI Rib Waveguides with Submicron Dimensions and Single Mode Operation

Full-vectorial finite difference method with perfectly matched layers boundaries is used to identify the single mode operation region of submicron rib waveguides fabricated using sili-con-on-insulator material system. Achieving high mode power confinement factors is emphasized while maintaining the single mode operation. As opposed to the case of large cross-section rib waveguides, theoretical single mode conditions have been demonstrated to hold for sub-micron waveguides with accuracy approaching 100%. Both, the deeply and the shallowly etched rib waveguides have been considered and the single mode condition for entire sub-micrometer range is presented while adhering to design specific mode confinement requirements.

Self Phase Modulation and Cross Phase Modulation in Nonlinear Silicon Waveguides for On-Chip Optical Networks -- A Tutorial

Silicon is a nonlinear material and optics based on silicon makes use of these nonlinearities to realize various functionalities required for on-chip communications. This article describes foundations of these nonlinearities in silicon at length. Particularly, self phase modulation and cross phase modulation in the context of integrated on-board and on-chip communications are presented. Important published results and principles of working of these nonlinearities are presented in considerable detail for non-expert readers.

Full 3D Model of Modulation Efficiency of Complementary Metal Oxide Semiconductor (CMOS) Compatible, Submicron, Interleaved Junction Optical Phase Shifters

Performance optimization associated with optical modulators requires reasonably accurate predictive models for key figures of merit. Interleaved PN-junction topology offers the maximum mode/junction overlap and is the most efficient modulator in depletion-mode of operation. Due to its structure, the accurate modelling process must be fully three-dimensional, which is a nontrivial computational problem. This paper presents a rigorous 3D model for the modulation efficiency of silicon-on-insulator interleaved junction optical phase modulators with submicron dimensions. Solution of Drift-Diffusion and Poisson equations were carried out on 3D finite-element-mesh and Maxwell equations were solved using Finite-Difference-Time-Domain (FDTD) method on 3D Yee-cells. Whole of the modelling process has been detailed and all the coefficients required in the model are presented. Model validation suggests < 10% RMS error.