Three-dimensional photonic crystal structures achieved with self-organization of colloidal particles

Three-dimensional polystyrene/air photonic crystal structure with different particle diameters: 200, 270 and 340 nm was achieved. Strong photonic band gap effect reflected with transmission minimum down to –16 dB was observed. The central wavelengths of the valleys of spectra were well fitted with theoretical calculation. The augmentation of band gap effect versus particle diameter was attributed to an improved self-assembling of particles. An analysis of transmission spectra is also presented. The agreement between the results of experiment and numerical analysis is good.     

Fabrication and characterization of direct-written 3D TiO_2 woodpile electromagnetic bandgap structures

Three groups of three-dimensional(3D) TiO2 woodpile electromagnetic gap materials with tailed rheological properties were developed for direct-written fabrication. Appropriate amount of polyethyleneimine(PEI) dispersants allow the preparation of TiO2 inks with a high solid content of 42 vol.%, which enables them to flow through the nozzles easily.The inks exhibit pseudoplastic behavior. The measured microwave characteristics of the results agree well with simulations based on plane wave expansion(PWE).     

Local imaging of photonic structures: image contrast from impedance mismatch

Photonic structures made from square arrays of air holes in Si(3)N(x) membranes are locally imaged by near-field optical microscopy in illumination mode. Holes with diameters smaller than and larger than the wavelength of light are investigated. Counterintuitively, the holes appear dark and the film is bright in transmission images for both hole sizes. Modeling shows that the dominant contrast mechanism is enhanced light emission from the tip when the tip is above the film. Tip emission is enhanced because the tip-air impedance mismatch is reduced when the tip is above the high-index film.     

Tetragonal photonic woodpile structures

The photonic properties of dielectric woodpile structures with face-centered-tetragonal (fct) and body-centered-tetragonal (bct) lattice symmetries are theoretically studied. Computational calculation of the photonic band structure reveals a photonic band gap between the second and third photonic band in both symmetries. A complete photonic band gap is not found in the bct structure due to a band gap shift with variable direction of lightflow. When the degree of layer disorder in fct woodpiles is increased, the stop bands slightly narrow and the attenuation of the optical transmission is reduced. Even so, layer-to-layer misalignment in dielectric woodpile structures may be tolerable up to 20–30% in most applications. The complete photonic band gap in fct woodpiles remains open with planar layer-to-layer disorder up to 60–70%.     

Photospin-orbit coupling in photonic structures

We show that the inclusion of nonlocality in the constitutive relations in photonic structures has important repercussions in their eigenmode configuration and distribution. In the case of optical activity, the primary manifestation of nonlocality, these features are traced to a photospin-orbit interaction analogous to the electron spin-orbit interaction in asymmetric semiconducting compounds; its impact can be assimilated to that of a magnetic field whose magnitude and direction follow that of the photon quasimomentum, with implications in photospin transport and photospintronics.     

Optimized structures for photonic quasicrystals

A photonic quasicrystal consists of two or more dielectric materials arranged in a quasiperiodic pattern with noncrystallographic symmetry that has a photonic band gap. We use a novel method to find the pattern with the widest TM-polarized gap for two-component materials. Patterns are obtained by computing a finite sum of density waves, assigning regions where the sum exceeds a threshold to a material with one dielectric constant, epsilon1, and all other regions to another, epsilon0. Compared to optimized crystals, optimized quasicrystals have larger gaps at low constrasts epsilon1/epsilon0 and have gaps that are much more isotropic for all contrasts. For high contrasts, optimized hexagonal crystals have the largest gaps.     

Three-dimensional photonic component for multichannel coherence measurements

We present the experimental results of a three-dimensional integrated photonic component designed for the simultaneous determination of mutual coherence properties of three light channels. Potential applications to astronomical optical interferometry are proposed and discussed.     

Three-dimensional mid-infrared photonic circuits in chalcogenide glass

We report the fabrication of single-mode buried channel waveguides for the whole mid-IR transparency range of chalcogenide sulphide glasses (λ ≤ 11 μm), by means of direct laser writing. We have explored the potential of this technology by fabricating a prototype three-dimensional three-beam combiner for future application in stellar interferometry that delivers a monochromatic interference visibility of 99.89% at 10.6 μm and an ultrahigh bandwidth (3-11 μm) interference visibility of 21.3%. These results demonstrate that it is possible to harness the whole transparency range offered by chalcogenide glasses on a single on-chip instrument by means of direct laser writing, a finding that may be of key significance in future technologies such as astrophotonics and biochemical sensing.     

Twist defect in chiral photonic structures

We demonstrate that twisting one part of a chiral photonic structure about its helical axis produces a single circularly polarized localized mode that gives rise to an anomalous crossover in propagation. Up to a crossover thickness, this defect results in a peak in transmission and exponential scaling of the linewidth for a circularly polarized wave with the same handedness as structure. Above the crossover, however, the linewidth saturates and the defect mode can be excited only by the oppositely polarized wave, resulting in a peak in reflection instead of transmission.     

Three-dimensional photonic quasicrystal with a complete band gap

The band structure of three-dimensional cubic approximants of a photonic quasicrystal has been determined by numerical calculation. The approximants of different orders appear to have large, almost isotropic, band gaps in a wide range of relative permittivity values. The existence of the complete band gap in the photonic quasicrystal with the six-dimensional bcc lattice is shown.     

光子人工微结构材料中的若干类量子现象

类量子现象又称为量子现象的经典对应(quantum-classical analogies),它是利用经典波动行为与量子波动行为的相似性来模拟和研究量子现象.近年来,光子人工微结构材料中类量子现象研究很活跃,文章对这方面的有关研究进展做了简要介绍.内容主要包括光子晶体和超构材料(metamaterials)中的类凝聚态系统量子现象和类原子系统量子现象,如类石墨烯量子现象、类拓扑绝缘体量子现象、类量子动力学现象、类Rabi振荡现象、类电磁感应透明现象、类Fano共振现象等.     

Three-dimensional photonic crystals as a cage for light

We review recent developments in three-dimensional photonic crystals. State of the art fabrication methods, such as layer-by-layer micromachining, self-assembly and various etching, lithographic and holographic techniques are discussed. We present an overview of optical studies of photonic band gap formation, such as reflectivity, transmission and time-resolved pulse propagation experiments. The fundamental issues associated with disorder and absorption are also considered. Progress towards the ultimate goal of full spontaneous emission control is reviewed. Finally, remaining open questions are summarized. To cite this article: A.F. Koenderink et al., C. R. Physique 3 (2002) 67–77     

Tomographic imaging of photonic crystal fibers

The tomographic reconstruction of the refractive index distribution in a large-mode-area photonic fiber is presented. The results of the diffraction tomographic algorithm and classical filtered backprojection method are compared. Additionally, the application of the synthetic aperture technique to tomographic interferometry, as a tool for resolution enhancement, is presented and discussed.     

Three-dimensional polarimetric integral imaging

A three-dimensional (3D) polarimetric image sensing and display technique based on integral imaging is proposed. Three-dimensional polarization distribution of reflected light from a 3D object can be measured as elemental image arrays by a rotating linear polarizer. After the measurement of the polarization of the 3D object, the 3D polarimetric object can be reconstructed optically by displaying the polarization-selected elemental images in spatial light modulators with two quarter-wave plates. Experimental demonstration of 3D polarimetric imaging of a 3D object attached to two orthogonal linear polarizers is presented. To the best of our knowledge, this is the first report on 3D polarimetric sensing imaging and 3D optical reconstruction by integral imaging.     

Three-dimensional spectrally encoded imaging

A method for three-dimensional surface measurements with phase-sensitive spectrally encoded imaging is demonstrated. Both transverse and depth information is transmitted through a single-mode optical fiber, allowing this scheme to be incorporated into a miniature probe. This approach is demonstrated by measurement of the profile of a lens surface and by three-dimensional imaging of the face of a small doll.     

Three-dimensional integral imaging of micro-objects

We propose a method for displaying micro-objects in space that is based on three-dimensional (3D) integral imaging, in which elemental images are calculated from a two-dimensional sampling of the optical field along different depths by use of confocal scanning microscopy. Experimental results are presented to demonstrate that a uniformly magnified 3D biological specimen can be displayed in space, and thus integral imaging can be used for 3D display of confocal microscopy. To the best of our knowledge, this is the first report of 3D integral imaging of (semitransparent) micro-objects.     

Band structures in nonlinear photonic crystal slabs

The finite-difference time-domain method was used to analyze band structures in two-dimensional Kerr-nonlinear photonic crystal slabs. A triangular lattice of circular air rods was considered. Results show red-shifting of the band structure due to the nonlinearity and the incident intensity. The red-shift of the band gap between the first and the second bands is maximal when the air rod radius is in the range 0.2a to 0.25a, where a is the period.     

Interference grating structures in photonic crystal circuits

Photonic Crystal Circuits have been widely investigated for various optoelectronics device applications. And the gratings in photonics devices are indispensable tool, which is very common for light manipulation. In this study, an interference grating structure formed by Gaussian beam interferences in photonic crystal waveguide such that having Kerr type nonlinearity is proposed and its transmission characteristics are investigated. Finite-Difference Time-Domain method is used to analyze the device characteristics. According to simulation results, the interference grating has shown special transmission characteristics that can bring tunability for photonic crystal devices. This can be an effective method for controlling optical signals in the photonic crystal for all optical switching/routing applications as a part of add/drop multiplexing.     

Optically controllable photonic structures with zero absorption

We show the possibility to periodically modulate the refractive index in a homogeneous resonant atomic medium in space or/and time while simultaneously keeping vanishing absorption or gain. Such modulation is based on periodic resonant enhancement of the refractive index, controlled by an external optical field, and opens the way to produce coherently controllable photonic structures. We suggest the possible implementation of the proposed scheme in rare-earth doped crystals with excited state absorption.     

Spectral self-similarity in fractal one-dimensional photonic structures

Transmission spectra of one-dimensional fractal multilayer structures are found to exhibit self-similar properties. Self-similarity manifests itself in the shape of a transmission envelope (map of transmission dips) rather than in the map of resonance transmission peaks, as is commonly the case with spectra of quasiperiodic systems. To observe the self-similarity, one needs to apply a power transformation to the transmittance in addition to the usual frequency scaling. The values of this power as well as the scaling factor have been calculated analytically and found to depend on the geometrical parameters of the structure.