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Cataloged from PDF version of article. Strongly asymmetric Fabry-Perot-type transmission arising at the two-way coupling has been studied in the case of normal incidence for slabs of two-dimensional photonic crystals (PCs) with one-sided corrugations that are made of linear isotropic materials. Comparing to the scenario of unidirectional transmission known for the structures with broken spatial inversion symmetry that requires zero order being uncoupled, in the studied mechanism zero order is either the sole order or one of the orders that may be coupled to a Floquet-Bloch mode. Contrary to the earlier studies of asymmetric transmission at the coupled zero order, structures with nondeep corrugations are considered, which allow one to combine Fabry-Perot-type total-transmission maxima with diffractions in a desired way. At a proper choice of PC lattice and corrugation parameters, higher orders can dominate in Fabry-Perot-type transmission at the noncorrugated-side illumination and also at the total-transmission maxima, whereas only zero order contributes to the transmission at the corrugated-side illumination. As a result, strong asymmetry can be obtained without uncoupling of zero order but it invokes the unidirectional contribution of higher orders. The presented results show that the entire structure can be approximately decomposed into the two independent, regular and grating (nonregular), parts whose contributions to the transmission are additive. Multiple asymmetric transmission maxima can coexist with a rather high equivalent group index of refraction. Possible applications of the studied transmission mechanism are discussed.

An electromagnetic nondiffractive Bessel-like beam from a subwavelength aperture is generated by placing a metallic circular gratinglike structure in front of the aperture. When the incident wave is linearly polarized, the beam is axially asymmetric. The beam possesses fluctuating, but approximately uniform, intensity distribution along its longitudinal axis. The full width at half maximum of the beam remains less than two wavelengths over nearly ten wavelengths. Our experimental results are in good agreement with the simulation results and analytical results. © 2009 The American Physical Society.

We report the spectral refraction analysis and focusing properties of a two-dimensional, dielectric photoniccrystal (PC) slab in freespace. A transverse electric polarized upper band of the crystal is used. The measuredrefraction spectra indicates that a highly isotropic negative index of refraction is present in the measuredfrequency range of the band. We demonstrate experimentally and numerically the focusing of the field emittedfrom an omnidirectional source placed in front of the crystal. Both the source and the focus pattern are awayfrom the PC interfaces of the order of several wavelengths. The focus pattern mimics the arbitrary lateral andlongitudinal shifts of the source, which is a manifestation of true flat lens behavior.DOI: 10.1103/PhysRevB.70.205125 PACS number(s): 42.25.2p, 78.20.Ci, 42.79.BhI. INTRODUCTION