P. Paddon

Observation of leaky slab modes in an air-bridged semiconductor waveguide with a two-dimensional photonic lattice

An air-bridged, 120-nm-thick semiconductor slab with a two-dimensional (2D) square array of through holes on a 480 nm pitch (Λ) was fabricated using selective wet etching techniques. The second order photonic resonances of the structure were studied by comparing broadband optical scattering data with numerical solutions of Maxwell’s equations. Features observed in these spectra over a 1200 cm−1 range, near 9500 cm−1, indicate that the 2D texture splits the energy degeneracy of slab modes with propagation constants {±2π/Λ,0} and {0,±2π/Λ} by as much as 14%.

Resonant scattering and mode coupling in two-dimensional textured planar waveguides

A heuristic formalism is developed for efficiently determining the specular reflectivity spectrum of two-dimensionally textured planar waveguides. The formalism is based on a Greens function approach wherein the electric fields are assumed to vary little over the thickness of the textured part of the waveguide. Its accuracy, when the thickness of the textured region is much smaller than the wavelength of relevant radiation, is verified by comparison with a much less efficient, exact finite difference solution of Maxwells equations. In addition to its numerical efficiency, the formalism provides an intuitive explanation of Fano-like features evident in the specular reflectivity spectrum when the incident radiation is phase matched to excite leaky electromagnetic modes attached to the waveguide. By associating various Fourier components of the scattered field with bare slab modes, the dispersion, unique polarization properties, and lifetimes of these Fano-like features are explained in terms of photonic eigenmodes that reveal the renormalization of the slab modes due to interaction with the two-dimensional grating. An application of the formalism, in the analysis of polarization-insensitive notch filters, is also discussed.

Near-infrared refractive index of thick, laterally oxidized AlGaAs cladding layers

The optical transmission in the range 900-1600 nm was measured through thick (/spl sim/1 /spl mu/m) layers of Al/sub 0.98/Ga/sub 0.02/As wet-oxidized at 375/spl deg/C on GaAs. The spectra are fit well by neglecting absorption, and using 1.61 for the refractive index.

SIMPLE APPROACH TO COUPLING IN TEXTURED PLANAR WAVEGUIDES

We develop a self-consistent Greens function technique to calculate the full photonic band structure for guided modes in slab waveguides that have been textured in one dimension with a thin surface grating. The technique is conceptually simple and can easily be reduced to an eigenvalue problem by use of approximations similar to those used in conventional coupled-mode theories. We show that this approach yields the correct TM-TM coupling coefficient at oblique incidence and provides a transparent interpretation for its vanishing at a critical angle.

Mode coupling in two-dimensionally textured planar waveguides

Summary form only given. We have developed a self-consistent Greens function formalism that quantitatively describes the dispersion and lifetimes of the photonic eigenstates of 2D textured waveguides. A 2D, vector coupled mode theory results by applying a simple approximation to our more general model.

Light scattering in free standing semiconductor slab waveguides exhibiting 2D photonic band structure

We have textured free-standing semiconductor slab waveguides with a 2D square lattice of through-holes.