Fano resonance and step-like transmission via guide-mode resonance structure

A two-layer guide-mode resonance structure made of shallow gratings deposited on the Kerr active guiding layer is used to realize high-quality Fano resonance and step-like transmission. The step-like transmission is designed to work between the perfect transmission peak and the dip of the asymmetrical Fano spectrum. It is demonstrated that the steep transition in the transmission should be attributed to the strong field localization in cases of both high and low transmission states.