Negative Refraction Angular Characterization in One-Dimensional Photonic Crystals

Background: Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity developed here. We also analytically derived the negative refraction correctness condition that gives the angular region where negative refraction occurs. Methodology/Principal Findings: By using standard photonic techniques we experimentally determined the relationship between incidence and negative refraction angles and found the negative refraction range by applying the correctness condition. In order to compare both theories with experimental results an output refraction correction was utilized. The correction uses Snell’s law and an effective refractive index based on two effective dielectric constants. We found good agreement between experiment and both theories in the negative refraction zone. Conclusions/Significance: Since both theories and the experimental observations agreed well in the negative refraction region, we can use both negative refraction theories plus the output correction to predict negative refraction angles. This can be very useful from a practical point of view for space filtering applications such as a photonic demultiplexer or fo

Bound modes of two-dimensional photonic crystal waveguides

It is now widely recognised that a volume of dielectric material with an appropriately designed periodic microstructure — a photonic crystal — will support a full three-dimensional photonic band gap (PBG). Over the frequency range spanned by the PBG, all electromagnetic modes are suppressed within the volume, allowing a single resonance (or photonic state) to be introduced by means of a structural point defect. This unique ability to tamper strongly with the electromagnetic mode density enables the channelling of spontaneous emission into one or a few electromagnetic modes, and is attractive for enhancing the emission rate from light emitting diodes, and in achieving low threshold highly efficient operation in micro-cavity lasers.Although photonic crystals with full PBGs at optical frequencies seem set to have a revolutionary impact in optoelectronics, they are not yet available, largely because the technological demands on nanofabrication challenge the current limits of the state-of-the-art. As several groups have realised, however, it is less demanding to produce two-dimensional periodic patterns in thin film form (see Figure I), and thus — perhaps — to achieve a full PBG in two dimensions. One important potential application of such photonic crystal waveguides is in the suppression of lateral emission in arrays of closely spaced vertical cavity emitting lasers

Stimulated Brillouin scattering from multi-GHz-guided acoustic phonons in nanostructured photonic crystal fibres

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