Aaron Matthews

Band-gap properties of two-dimensional low-index photonic crystals

We study the band-gap properties of two-dimensional photonic crystals created by a lattice of rods or holes conformed in a symmetric or asymmetric triangular structure. Using numerical plane-wave method, we calculate a minimum value of the refractive-index contrast for opening both partial and full two-dimensional spectral gaps for both TM- and TE-polarized waves. We also analyze the effect of ellipticity of rods and holes and their orientation on the threshold value and the relative size of the band gaps.

Photonic bandgap properties of void-based body-centered-cubic photonic crystals in polymer

We report on the fabrication and characterization of void-based body-centered-cubic (bcc) photonic crystals in a solidified transparent polymer by the use of a femtosecond laser-driven microexplosion method. The change in the refractive index in the region surrounding the void dots that form the bcc structures is verified by presenting confocal microscope images, and the bandgap properties are characterized by using a Fourier transform infrared spectrometer. The effect of the angle of incidence on the photonic bandgaps is also studied. We observe multiple stop gaps with a suppression rate of the main gap of 47% for a bcc structure with a lattice constant of 2.77 microm, where the first and second stop gaps are located at 3.7 microm and 2.2 microm, respectively. We also present a theoretical approach to characterize the refractive index of the material for calculating the bandgap spectra, and confirm that the wavelengths of the observed bandgaps are in good correlation with the analytical predictions.

Experimental studies of the internal Goos-Hanchen shift for self-collimated beams in two-dimensional microwave photonic crystals

We study experimentally the Goos–Hanchen effect observed at the reflection of a self-collimated beam from the surface of a two-dimensional photonic crystal and describe a method for controlling the beam reflection through surface engineering. The microwave photonic crystal, fabricated from alumina rods, allows control of the output position of a reflected beam undergoing an internal Goos–Hanchen shift by changing the rod diameter at the reflection surface. The experimental data are in good agreement with the results of the finite-difference time-domain numerical calculations.

Experimental demonstration of self-collimation beaming and splitting in photonic crystals at microwave frequencies

I studied experimentally beam self-collimation and splitting in two-dimensional microwave photonic crystals. Using a microwave photonic crystal fabricated from alumina rods, I present an experimental proof of principle for an earlier theoretical proposal [A.F. Matthews, S.K. Morrison, Yu.S. Kivshar, Opt. Commun. 279 (2007) 313] of a photonic crystal beam splitter based on the self-collimation effect.

Self-collimation and beam splitting in chalcogenide glass and photopolymer photonic crystals

Utilizing the parameters of two-dimensional photonic crystals fabricated in chalcogenide-glass slab waveguides and photopolymers we study numerically the self-collimation effect in low-index photonic crystals and suggest a novel type of beam splitter based on the beam self-collimation.

Analysis of three-dimensional photonic crystals fabricated by the microexplosion method

Fabrication of three-dimensional photonic crystals by the microexplosion techniques has recently been demonstrated by a number of groups. However, simple models which are currently used for characterizing the void-based photonic structures do not produce adequate results. Here, we suggest a new theoretical approach for analyzing the properties of the three-dimensional photonic crystals which allow to improve the results of the theoretical modeling of the photonic crystals created by the microexplosion method. In particular, we study the bandgap spectrum of the three-dimensional photonic crystals introducing a shell of a high-index material surrounding an air void in the face-centered-cubic lattice. This allows us to suggest an effective theoretical model which correlates very well with the properties of the microexplosion polymer photonic crystals produced experimentally. We also discuss some interesting effects observed in the fabricated photonic crystals which until now have not been understood due to the inadequacies of simple models.