Modal properties of a strip-loaded horizontal slot waveguide

Abstract

Background Channel waveguides have been developed for years to comply with the need for smaller footprint and better integration in photonics circuits. However, they are still suffering from fabrication complexity and optical losses. These two limitations can be addressed by combining two types of channel waveguides, namely strip-loaded and slot waveguide.

Methods We present a systematic study of the geometrical parameters of a strip-loaded horizontal slot waveguide and their influence on the characteristics of the device. Simulations and experiments are carried out to understand the behavior of the electromagnetic field inside such a waveguide. In particular, the influence of the high and low refractive index layers and the loading-strip on the key characteristics of the structure, i.e., the confinement factor and the effective index, are investigated theoretically and compared with experimental values.

Results The main properties of this waveguide platform are a low lateral index contrast, a high vertical field confinement, and low-propagation losses (1.4 dB/cm).

Conclusions Our results show that this platform is highly versatile, easy to fabricate and low-losses. We also show that the geometry of the mode can be tuned to suit the application.