Radiation losses of waveguide-based two-dimensional photonic crystals: Positive role of the substrate

Abstract

Radiation losses occurring in photonic crystals etched into planar waveguides are analyzed using a first-order perturbation approximation. Assuming the incoherent scattering limit, the model indicates that losses diminish as the cladding index approaches the core index. A simple scheme is devised to include these losses into purely two-dimensional calculations by using an imaginary index. Such calculations are shown to agree with corresponding experimental transmission through near-infrared photonic crystals, reproducing the contrasting behavior of the “dielectric” and “air” band edges.

Modal behavior of single-line photonic crystal guiding structures on InP substrate

“…We include a phenomenological parameter ε im describing radiation loss in the third dimension, despite the 2D simulation model [19].…”

The smallest possible whispering-gallery-like mode in the square lattice photonic-crystal slab single-defect cavity

“…However, in the dipole mode of a normal triangular-lattice single defect, the is only several hundred [12], [13]. It has been pointed out that optical losses of the slab-type 2-D photonic-crystal cavity modes are dominated by the radiation loss out of the slab [12], [24], which implies that consideration of vertical coupling should be more important than that of in-plane mode confinement. Recently, Johnson et al proposed an idea that the vertical radiation loss is strongly dependent upon the mode shape [25].…”

Coupled nanopillar waveguides optical properties and applications

“…Due to the absence of a complete bandgap, the breaking of translational symmetry inevitably results in radiation losses of the resonator mode, which raises the need for optimizing the Q-factor of the resonator in 1D nanopillar waveguides. There have been some proposals to decrease the losses based on either mode delocalization [23] or on the effect of multipole cancellation [24]. A delocalized mode typically suffers from a decrease of the Q-factor.…”