Experimental and Theoretical Demonstration of Resonant Leaky-Mode in Grating Waveguide Structure with A Flattened Passband

Abstract

In this study, the first experimental demonstration of the strongly modulated refractive index of gratings with two distinct filling factors within one period is carried out for broadband guided mode resonance (GMR) filters. The proposed filters are realized by utilizing a single-layer poly-silicon film deposited on a quartz substrate. In order to clarify the unique features of strongly modulated gratings caused by subwavelength profiles with two filling factors in the lateral direction, dispersion relations and spectral responses are analyzed. A flattened bandstop spectral response of 85 nm with a transmittance of lower than -20 dB at a central wavelength of 1.22 µm and a high immunity to the angular deviation of incident wave up to 20° are experimentally obtained. Compared with the strongly modulated gratings achieved using longitudinal cascaded GMR filters, the proposed two-filling-factor gratings have a more compact design and are more suitable for further integration with other optoelectronic components.