Silicon-on-Insulator Slot Waveguides: Theory and Applications in Electro-Optics and Optical Sensing

Abstract

This chapter deals with the basic concept of silicon-on-insulator (SOI) slot waveguides, including slot waveguide theory, fabrication steps, and applications. First, in the theory section, a modal field expression and the characteristic equation is derived, which is also valid for higher-order modes. SOI slot waveguide structures are simulated and characteristic values like the effective refractive indices and the field confinement factors are determined. The fabrication section describes typical SOI fabrication steps and the limits of current fabrication techniques. Additionally, developments regarding loss reduction in SOI slot waveguides are given from the fabrication point of view. This is followed by the theory and practice of slot waveguide based electro-optical modulators. Here, the SOI slot waveguide is embedded in an organic nonlinear optical material in order to achieve record-low voltage-length products. In the field of optical sensors, it is shown that slot waveguides enable remarkable waveguide sensitivity for both refractive index sensing and surface sensing.

On-Chip Dispersion Measurement of the Quadratic Electro-Optic Effect in Nonlinear Optical Polymers Using a Photonic Integrated Circuit Technology

“…A more comprehensive description of such CMOS-compatible slot waveguide design can be found in Refs. [26], [27]. In particular, a simulation study of slot waveguides comprising the same EO polymer as in the present work can be found in Ref.…”

Optical Biosensors Based on Silicon-On-Insulator Ring Resonators: A Review

“…The most important component of all integrated photonic biosensors is the silicon waveguide. During the last decade, many effort has been undertaken to improve waveguide geometries for optical sensing by simulation studies [38,39,40]. In principle, there are three types of widely used waveguides, namely strip waveguide, rib waveguide and slot waveguide, as illustrated in Figure 2.…”

Comparative Study of Nano-Slot Silicon Waveguides Covered by Dye Doped and Undoped Polymer Cladding

“…The performance of those devices is achieved by the introduction of SOI slot-waveguides with polymer-clad. Within a narrow, low-index gap region, slot-waveguides offer a high optical field confinement [7], which can be exploited to efficiently modulate the guided mode. The large optical and electrical field overlap in SOI slot-waveguides allows for ultra-efficient EO modulation.…”