Three-dimensional crystals of air spheres in titania (TiO 2 ) with radii between 120 and 1000 nanometers were made by filling the voids in artificial opals by precipitation from a liquid-phase chemical reaction and subsequently removing the original opal material by calcination. These macroporous materials are a new class of photonic band gap crystals for the optical spectrum. Scanning electron microscopy, Raman spectroscopy, and optical microscopy confirm the quality of the samples, and optical reflectivity demonstrates that the crystals are strongly photonic and near that needed to exhibit band gap behavior.

https://science.sciencemag.org/content/sci/281/5378/802.full.pdf

Preparation of photonic crystals made of air spheres in titania

This Review summarizes recent developments in the field of responsive photonic crystal structures, including principles for design and fabrication and many strategies for applications, for example as optical switches or chemical and biological sensors. A number of fabrication methods are now available to realize responsive photonic structures, the majority of which rely on self-assembly processes to achieve ordering. Compared with microfabrication techniques, self-assembly approaches have lower processing costs and higher production efficiency, however, major efforts are still needed to further develop such approaches. In fact, some emerging techniques such as spin coating, magnetic assembly, and flow-induced self-assembly have already shown great promise in overcoming current challenges. When designing new systems with improved performance, it is always helpful to bear in mind the lessons learnt from natural photonic structures.

Responsive photonic crystals.

This Review covers photonic crystals (PhCs) and their use for sensing mainly chemical and biochemical parameters, with a particular focus on the materials applied. Specific sections are devoted to a) a lead-in into natural and synthetic photonic nanoarchitectures, b) the various kinds of structures of PhCs, c) reflection and diffraction in PhCs, d) aspects of sensing based on mechanical, thermal, optical, electrical, magnetic, and purely chemical stimuli, e) aspects of biosensing based on biomolecules incorporated into PhCs, and f) current trends and limitations of such sensors.

Photonic Crystals for Chemical Sensing and Biosensing

Photonic crystals have proven their potential and are nowadays a familiar concept. They have been approached from many scientific and technological flanks. Among the many techniques devised to implement this technology self-assembly has always been one of great popularity surely due to its ease of access and the richness of results offered. Self-assembly is also probably the approach entailing more materials aspects owing to the fact that they lend themselves to be fabricated by a great many, very different methods on a vast variety of materials and to multiple purposes. To these well-known material systems a new sibling has been born (photonic glass) expanding the paradigm of optical materials inspired by solid state physics crystal concept. It is expected that they may become an important player in the near future not only because they complement the properties of photonic crystals but because they entice the researchers' curiosity. In this review a panorama is presented of the state of the art in this field with the view to serve a broad community concerned with materials aspects of photonic structures and more so those interested in self-assembly.

/pdf/self-assembled-photonic-structures-4qp8mc5drj.pdf

Self-assembled photonic structures.

http://nathan.instras.com/documentDB/paper-89.pdf

Photonic crystals in the optical regime — past, present and future

We report on the photonic band gap phenomenon in the visible range in a three-dimensional dielectric lattice formed by close-packed spherical silica clusters. The spectral position and the spectral width of the optical stop band depend on the direction of light propagation with respect to the crystal axes of opal, and on the relative cluster-to-cavity refraction index n. Manifestations of the photonic pseudogap have been established for both transmission and emission spectra. The stop band peak wavelength shows a linear dependence on n. Transmission characteristics of the lattice have been successfully simulated by numerical calculations within the framework of a quasicrystalline approximation. @S1063-651X~97!13805-3#

/pdf/photonic-band-gap-phenomenon-and-optical-properties-of-2qpuu2mbav.pdf

Photonic band gap phenomenon and optical properties of artificial opals

We report on the photonic band gap effect in the visible range in a three-dimensional dielectric lattice formed by closely packed silica spherical clusters and by interconnected cavities filled with various liquids. The spectral position and the spectral width of the optical "stop-band" depend on the lattice period and on the relative sphere/cavity refraction indexn. The stop band peak wavelength shows a linear dependence on n. Transmission characteristics of the lattice have been successfully simulated by numerical calculations within the framework of a quasicrystalline approximation.

Photonic band gap in the visible range in a three-dimensional solid state lattice

We report on the photonic band gap effect in the visible range in a three-dimensional dielectric lattice formed by closely packed silica spherical clusters and by intercon- nected cavities filled with various liquids. The spectral posi- tion and the spectral width of the optical "stop-band" depend on the lattice period and on the relative sphere/cavity refrac- tion index n. The stop band peak wavelength shows a linear dependence on n. Transmission characteristics of the lattice have been successfully simulated by numerical calculations within the framework of a quasicrystalline approximation.

/pdf/rapid-communication-photonic-band-gap-in-the-visible-range-qfdroyijgj.pdf

Rapid communication Photonic band gap in the visible range in a three-dimensional solid state lattice

THREE-DIMENSIONAL PHOTONIC BAND GAP STRUCTURES DOPED WITH Tb3+ IONS

Porous synthetic opal possessing a three-dimensional photonic band structure of semimetallic type was impregnated with polycrystalline CdS. The photonic stop band in (111) direction was examined by means of photoreflection technique. Under cw laser excitation of semiconductor inclusions the reflectance of the system changes indicating a modification of photonic band structure. A possible mechanism is discussed. Numerical simulations within the framework of quasicrystalline approximation are given. PACS numbers: 42.70.Qs, 42.70.Gi

/pdf/light-induced-modification-of-3d-photonic-band-structure-4p955h9klx.pdf

A. N. Ponyavina

Papers

Photonic band gap phenomenon and optical properties of artificial opals

Photonic band gap in the visible range in a three-dimensional solid state lattice

Rapid communication Photonic band gap in the visible range in a three-dimensional solid state lattice

THREE-DIMENSIONAL PHOTONIC BAND GAP STRUCTURES DOPED WITH Tb3+ IONS

Light-Induced Modification of 3D Photonic Band Structure Detected by Means of Photoreflection