Squeezing Light in Wires: Fundamental Optical Properties of Si Nanowire Waveguides

Single-mode Si-wire waveguides, fabricated in the Si-on-insulator platform, are the basis for a growing number of potential applications in linear and nonlinear integrated optical devices and systems. This paper reviews the fundamental optical physics and behavior of these waveguides and demonstrates how their reduced transverse dimensions and index contrast lead to a series of unique and distinct modal properties. These properties include readily tunable waveguide dispersion (including dispersion flattening), large longitudinal fields, a decrease in group velocity over those of the bulk materials, and anisotropic nonlinear optical properties. In turn, new devices and device structures are achievable as a result of these features and examples of new device structures are provided.