V. Pacradouni

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.

Linear and nonlinear optical properties of planar photonic crystals

We have subsequently developed planar photonic crystals (PPCs) specifically for nonlinear optical conversion studies. In particular we designed and realized a square-lattice PPC that has bands that exhibit almost no dispersion along the entire /spl Gamma/-X direction of the square Brillouin zone. These flat bands offer tuning flexibility and conversion efficiency advantages when considering PPCs as hosts for 2 nd harmonic generation. We have recently extended our self-consistent scattering model to include 2 nd order polarization terms. This allows us to estimate the absolute external second harmonic generation efficiency in specular reflection when exciting the PPC from the top half space.

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.

Contribution of single InGaAs quantum wells to the guided mode dispersion of InGaAs/GaAs/AlGaAs waveguides: Model and experimental results

High resolution Fabry–Perot fringe spacing measurements are used to determine the group index dispersion of TE and TM polarized modes in single quantum well InGaAs/AlGaAs/GaAs graded index separate confinement heterostructure waveguides. The TE mode data, over a ∼175 nm range below the quantum well band gap, is compared with model calculations of guided mode dispersion using existing empirical formulas for the index dispersion of AlxGa1−xAs and GaAs, and different phenomenological expressions for the TE index dispersion of the InGaAs quantum well. A satisfactory fit is obtained when the quantum well is modeled as a two‐dimensional set of equal strength oscillators with a constant density of states, plus a single 1S excitonic level.