Morphology-dependent transmission through photonic crystals (original) (raw)
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Experimental studies of wave propagation in three-dimensional photonic crystals
2002
EXPERIMENTAL STUDIES OF WAVE PROPAGATION IN THREEDIMENSIONAL PHOTONIC CRYSTALS by John M. Tobias Photonic crystals were proposed fifteen years ago. Propagation is selectively prevented through these crystals resulting in a photonic band gap, that is, a frequency region where light cannot propagate. These frequency bands are analogous to electronic band gaps in solid-state crystals. The optical properties of the photonic crystal in regions near the band gap remain relatively unexplored. Yet, there is significant evidence to suggest that this avenue of investigation can provide useful optical and microwave applications. Numerical studies have predicted that the effective permittivity near the photonic band gap approaches zero and becomes negative. Self-collimation of the propagating beam and ultrarefraction, where radiation is redirected through large angles in the crystal, are predicted. Although not considered as the ideal structure, the face centered cubic (fcc) opaline photonic is...
Microwave Applications of Photonic Crystals
Progress in Electromagnetics Research-pier, 2003
We have demonstrated guiding and bending of electromagnetic (EM) waves in planar and coupled-cavity waveguides built around three-dimensional layer-by-layer photonic crystals. We observed full transmission of the EM waves through these waveguide structures. The dispersion relations obtained from the experiments were in good agreement with the predictions of our waveguide models. We also reported a resonant cavity enhanced (RCE) effect by placing microwave detectors in defect structures. A power enhancement factor of 3450 was measured for planar cavity structures. Similar defects were used to achieve highly directional patterns from monopole antennas.
Three-Dimensional Photonic Crystal for Spatial Filtering
2011
It is well known that photonic crystals exhibit frequency band gaps. The main application of that property is that one can utilize it for a frequency filtering. Recently it has been proposed that angular band gaps in two and three-dimension photonic crystals can be similarly applied for a spatial filtering of light beams [1]. The purpose of this paper is to experimentally demonstrate that photonic crystals can spatially filter the light.
2008
Photonic crystals (PhCs) possess unique dispersion properties that can be exploited to enable novel photonic applications. These properties can also be used to significantly improve the performance of existing photonic devices. Many applications of PhCs such as waveguides, PC fibers and photonic cavities have been explored by using the presence of a photonic bandgap over a desired frequency range with a defect incorporated in the structure to allow only a desired mode to propagate. This strategy often requires a large index contrast between materials to create the band gap in the first place, which limits the materials that can be used for the photonic devices. On the other hand, many phenomena such as negative refraction, superprism, super-resolution, and slow light have been demonstrated based on unique spatial and temporal dispersion properties of a PhC and they are often observable with materials having a low index contrast. In my research we investigate self-collimation, another dispersion-related phenomenon of PhCs, that is manifested to some degree in all PhCs. In free space or homogeneous materials propagating electromagnetic waves spread due to diffraction effects, but a PhC in the region of self-collimation has essentially no diffraction and input beams spread over a range of input angles are collimated into a single direction. The phenomenon of beam-like propagation without divergence is important for many applications, including optical interconnects in an integrated circuit. Self-collimation provides a solution to beam control that does not require additional fabrication steps and can be used in conjunction with additional effects to further tailor the application needs. We develop a process to investigate the range of input angles and the degree of collimation of the beam inside the photonic crystal composed of anisotropic constituents. The optical properties of a photobleached 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST) crystal are used in our model to demonstrate the efficacy of the self-collimation features. In DAST we identified conditions where the divergence angle over a span of incident angles of 40 degrees can be less than 1 degree and the transmission remains high over the entire span of angles.
Experimental evidences of light beam filtering by three-dimensional photonic crystal
2010
We report first experimental evidences of spatial filtering of light beam in three-dimensional photonic crystals. The photonic crystals were fabricated in a glass bulk, where the refraction index was modified by applying femtosecond laser pulses. We observe the modification of the angular spectra (the far field) in the central maximum of the transmitted radiation in accordance with the theory of spatial filtering.
Radial Photonic Crystal for detection of frequency and position of radiation sources
2012
Based on the concepts of artificially microstructured materials, i.e. metamaterials, we present here the first practical realization of a radial wave crystal. This type of device was introduced as a theoretical proposal in the field of acoustics, and can be briefly defined as a structured medium with radial symmetry, where the constitutive parameters are invariant under radial geometrical translations. Our practical demonstration is realized in the electromagnetic microwave spectrum, because of the equivalence between the wave problems in both fields. A device has been designed, fabricated and experimentally characterized. It is able to perform beam shaping of punctual wave sources, and also to sense position and frequency of external radiators. Owing to the flexibility offered by the design concept, other possible applications are discussed.
Effect of spatial-time dispersion on the propagation of electromagnetic waves in photonic crystals
We study the influence of the space and time dispersion on the frequency dependence of the wave vectors of electromagnetic waves propagating in three-dimensional photonic crystals. Two types of structures are considered: media with weak periodic modulation of the permittivity, and photonic crystals composed of the periodically arranged identical resonant dielectric particles. It is shown that in these systems, in contrast to electrons in solid crystals, different types of excitations exist. For example, a peculiar kind of polaritons arises in the photonic crystals due to the interaction of the electromagnetic field, eigenoscillations of the dielectric medium, and Debye resonance. The widths of the transparency zones and of the band gaps have been calculated as functions of the frequency and of the parameters of the media. It is shown that in the photonic crystals with dispersion, the number of transparency bands is larger than in nondispersive systems, and the width of the gaps in the frequency spectrum of photons depends on the wave vector. The interaction of different types of waves deforms the Brillouin zone, so that it may not have a plane boundary (for example, a sphere), in which case the classical Bragg condition does not hold.
Guiding waves with photonic crystals
Optics Communications, 1999
We study a finite doped photonic crystal using a rigorous theory of diffraction. We exhibit a structure allowing to guide two bands of wavelengths in two different regions of the crystal. Rigorous numerical results are given showing the localization of the electromagnetic energy inside the crystal. Such a device could be of great use for the realization of filters. q
Photonic crystals as host material for a new generation of microwave components
Advances in Radio Science, 2006
In order to verify simulations of a concave lens based upon a photonic crystal, it was scaled and built for the application in the microwave range. Its field distribution was measured between 5.5 and 12 GHz. Due to the effective refractive index smaller than 1, focusing points were found in spite of the concave shape. The survey of the field