Surface sensing with integrated optical waveguides: a design guideline

Abstract

Waveguide-based biochemical sensors exploit detection of target molecules that bind specifically to a functionalized waveguide surface. For optimum sensitivity, the waveguide should be designed to mediate maximum influence of the surface layer on the effective refractive index of the guided mode. In this paper, we define a surface sensitivity metric which quantifies this impact and which allows to broadly compare different waveguide types and integration platforms. Focusing on silicon nitride and silicon-on-insulator (SOI) as the most common material systems, we systematically analyze and optimize a variety of waveguide types, comprising simple strips, slot and double slot structures, as well as sub-wavelength gratings (SWG). Comparing the highest achievable surface sensitivities, we provide universal design guidelines and physically interpret the observed trends and limitations. Our findings allow to select the appropriate WG platform and to optimize sensitivity for a given measurement task.

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

“…A comprehensive design guideline to choose the most appropriated waveguide type for a specific application can be found in Refs. [42,43]. To improve the sensor performance in terms of sensitivity, it is useful to distinguish between the waveguide sensitivity and the ring resonator sensitivity.…”

Advanced Optical Sensing of Phenolic Compounds for Environmental Applications

“…Usually, the different components can be chosen and assembled in accordance with the user's needs, or they are combined in a commercial spectrofluorometer, such as the one reported in Figure 4, in which two monochromators are used as wavelength selectors. As is evident from the literature, optical fibers and waveguide-based optical sensors have gained a large interest since they show enormous potential for applications in various fields [27][28][29][30][31]. In fact, fiber-optic sensors can have small size; are sensitive to multiple environmental parameters; allow remote sensing also into normally inaccessible areas; do not strictly require contact; are independent from radio frequency and electromagnetic interference; avoid contamination of their surrounding area; are characterized by high sensitivity, resolution, and dynamic range; and can be connected with data communication systems.…”

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

“…A comprehensive design guideline to choose the most appropriated waveguide type for a specific application can be found in Refs. [21,22]. The waveguide sensitivity is given by…”