Effect of vertical mode matching on defect resonances in one-dimensional photonic crystal slabs

In photonic crystal (PC) slabs, a major source of attenuation results from out-of-plane scattering due to the lack of vertical confinement of light within the holes. Here, we study single and multiple defect resonances in one-dimensional (1-D) slab PC structures that establish waveguiding within the holes as a means to reduce this attenuation mechanism. Two-dimensional (2-D) cross section simulations of light propagation show that, by closely matching the vertical mode profiles in the slab and the holes, the scattering loss can be significantly reduced. Even with simplified structures where the mode matching is imperfect, significant reduction in scattering loss can still be obtained, resulting in greater transmission and quality factor than the structures without confinement in the holes