Virtually all electronic and optoelectronic devices necessitate a challenging assembly of conducting, semiconducting and insulating materials into specific geometries with low-scattering interfaces and microscopic feature dimensions. A variety of wafer-based processing approaches have been developed to address these requirements, which although successful are at the same time inherently restricted by the wafer size, its planar geometry and the complexity associated with sequential high-precision processing steps. In contrast, optical-fibre drawing from a macroscopic preformed rod is simpler and yields extended lengths of uniform fibres. Recently, a new family of fibres composed of conductors, semiconductors and insulators has emerged. These fibres share the basic device attributes of their traditional electronic and optoelectronic counterparts, yet are fabricated using conventional preform-based fibre-processing methods, yielding kilometres of functional fibre devices. Two complementary approaches towards realizing sophisticated functions are explored: on the single-fibre level, the integration of a multiplicity of functional components into one fibre, and on the multiple-fibre level, the assembly of large-scale two- and three-dimensional geometric constructs made of many fibres. When applied together these two approaches pave the way to multifunctional fabric systems.
Conventional solid-core optical fibres require highly transparent materials. Such materials have been difficult to identify owing to the fundamental limitations associated with the propagation of light through solids, such as absorption, scattering and nonlinear effects. Hollow optical fibres offer the potential to minimize the dependence of light transmission on fibre material transparency. Here we report on the design and drawing of a hollow optical fibre lined with an interior omnidirectional dielectric mirror. Confinement of light in the hollow core is provided by the large photonic bandgaps established by the multiple alternating submicrometre-thick layers of a high-refractive-index glass and a low-refractive-index polymer. The fundamental and high-order transmission windows are determined by the layer dimensions and can be scaled from 0.75 to 10.6 micro m in wavelength. Tens of metres of hollow photonic bandgap fibres for transmission of carbon dioxide laser light at 10.6 micro m wavelength were drawn. The transmission losses are found to be less than 1.0 dB m(-1), orders of magnitude lower than those of the intrinsic fibre material, thus demonstrating that low attenuation can be achieved through structural design rather than high-transparency material selection.
We have experimentally observed the eigenmode splitting due to coupling of the evanescent defect modes in three-dimensional photonic crystals. The splitting was well explained with a theory based on the classical wave analog of the tight-binding ( TB) formalism in solid state physics. The experimental results were used to extract the TB parameters. A new type of waveguiding in a photonic crystal was demonstrated experimentally. A complete transmission was achieved throughout the entire waveguiding band. We have also obtained the dispersion relation for the waveguiding band of the coupled periodic defects from the transmission-phase measurements and from the TB calculations. PACS numbers: 42.70.Qs, 42.60.Da, 42.82.Et, 71.15.Fv The artificially created three-dimensional (3D) periodic structures inhibit the propagation of electromagnetic (EM) waves in a certain range of frequencies in all directions [1,2]. In analogy with electronic band gaps in semiconductors, these structures are called photonic band gap (PBG) materials or photonic crystals [3,4]. The initial interest in this area came from the proposal to use PBG crystals to control spontaneous emission in photonic devices [1]. However, the technological challenges restricted the experimental demonstrations and relevant applications of these crystals to millimeter wave and microwave frequencies [5][6][7]. Recently, Lin and Fleming reported a photonic crystal with a band gap at optical frequencies [8,9]. With this breakthrough, initially proposed applications like thresholdless semiconductor lasers [10] and single-mode light-emitting diodes [11,12] became feasible.By breaking the periodicity of the photonic crystal, it is possible to create highly localized defect modes within the photonic band gap, which are analogous to the localized impurity states in a semiconductor [13]. Photons hop from such a evanescent defect mode to the neighboring one due to overlapping of the tightly confined modes. This is exactly the classical wave analog of the tightbinding (TB) method in solid state physics [14,15]. The TB formulation has been proven to be very useful in studying electronic properties of solids [16,17]. Recently, the TB scheme was also successfully used for various photonic structures. Waveguiding along the impurity chains in photonic insulators [18], waveguiding through coupled resonators [19], and one-dimensional superstructure gratings [20] were theoretically investigated by using TB formalism. Lidorikis et al. tested the TB model by comparing the ab initio results of two-dimensional PBG structures with and without defects [21]. They obtained the TB parameters by an excellent fitting to ab initio results. Splitting of the coherent coupling of whispering gallery mode in quartz polystyrene spheres were reported and explained within the TB photon picture [22]. The optical modes in the micrometer-sized semiconductor coupled cavities were investigated by Bayer et al. [23].In this Letter, we investigated experimentally and theoretically the coupling between locali...
We report the design and fabrication of a multilayered macroscopic fiber preform and the subsequent drawing and optical characterization of extended lengths of omnidirectional dielectric mirror fibers with submicrometer layer thickness. A pair of glassy materials with substantially different indices of refraction, but with similar thermomechanical properties, was used to construct 21 layers of alternating refractive index surrounding a tough polymer core. Large directional photonic band gaps and high reflection efficiencies comparable to those of the best metallic reflectors were obtained. Potential applications of these fibers include woven fabrics for radiation barriers, spectral authentication of cloth, and filters for telecommunications.
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