Characterization of low index Si waveguides

In recent years, silicon photonics has attracted attention as an emerging technology for optical telecommunications and for optical interconnects in microelectronics. The refractive index contrast plays a fundamental role in determining the characteristics of an optical dielectric waveguide and a higher index contrast permits to move towards larger scales of integration and to access new devices and functionalities. But high contrast waveguides are more difficult to realize and more critical but there are no serious impediments in their use. The aim of this contribution is to investigate the dependence of the waveguide characteristics with respect to the index contrast and explore the difficulties. In this paper, the impact of the index contrast on the characteristics of dielectric waveguides such as single mode regime, losses, fiber to waveguide coupling, technological constraints and available materials are investigated. The investigation shows that the dependence of the sensitivity in optical waveguide sensors on the polarization of guided modes is less in small refractive index difference waveguide compare than the silicon on silica waveguides but it provide flexibility to the design engineers.