Enhancement of evanescent field ratio in a silicon strip waveguide by incorporating a thin metal film

Abstract

In this work, we propose a metal-assisted silicon strip waveguide design to improve the evanescent field ratio, which can be used in highly sensitive sensor applications. To prove the dominance of our proposed design, we make a reasonable comparison with the conventional silicon strip waveguide of similar geometry. In the structure of the metal-assisted waveguide, a thin SiO2 layer is sandwiched between the gold and the silicon strip waveguide. The transmission spectrum and E-field distribution of these structures are simulated using the 3D-finite element method. We have demonstrated the enhancement of the evanescent field in the upper cladding region of a straight strip waveguide which makes it an ideal candidate as an evanescent field gas absorption sensor.