The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Organic–inorganic hybrid materials do not represent only a creative alternative to design new materials and compounds for academic research, but their improved or unusual features allow the development of innovative industrial applications. Nowadays, most of the hybrid materials that have already entered the market are synthesised and processed by using conventional soft chemistry based routes developed in the eighties. These processes are based on: a) the copolymerisation of functional organosilanes, macromonomers, and metal alkoxides, b) the encapsulation of organic components within sol–gel derived silica or metallic oxides, c) the organic functionalisation of nanofillers, nanoclays or other compounds with lamellar structures, etc. The chemical strategies (self-assembly, nanobuilding block approaches, hybrid MOF (Metal Organic Frameworks), integrative synthesis, coupled processes, bio-inspired strategies, etc.) offered nowadays by academic research allow, through an intelligent tuned coding, the development of a new vectorial chemistry, able to direct the assembling of a large variety of structurally well defined nano-objects into complex hybrid architectures hierarchically organised in terms of structure and functions. Looking to the future, there is no doubt that these new generations of hybrid materials, born from the very fruitful activities in this research field, will open a land of promising applications in many areas: optics, electronics, ionics, mechanics, energy, environment, biology, medicine for example as membranes and separation devices, functional smart coatings, fuel and solar cells, catalysts, sensors, etc.

Applications of hybrid organic–inorganic nanocomposites

Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Investigations of two-photon polymerization of inorganic-organic hybrid materials initiated by femtosecond Ti:sapphire laser pulses are performed. First applications of this technique for the fabrication of three-dimensional microstructures and photonic crystals in inorganic-organic hybrid polymers with a structure size down to 200 nm and a periodicity of 450 nm are discussed.

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Femtosecond laser-induced two-photon polymerization of inorganic-organic hybrid materials for applications in photonics.

Sol-gel synthesis allows inorganic–organic hybrid polymer materials (ORMOCER®s) to be produced, which can be functionalized to tailor their physical and chemical properties such as refractive index or optical loss. A particular material system is discussed here, which is synthesized without addition of water and is applied in optical communications. As examples for 2D and 2.5D technology, planar waveguides, stacked waveguides, and microlenses are shown. Using two-photon polymerization initiated by femtosecond laser pulses, arbitrary 3D structures can be made in the submicrometer range. In particular, 3D photonic crystal structures are described and discussed.

Inorganic–Organic Hybrid Polymers for Information Technology: from Planar Technology to 3D Nanostructures

A flexible approach to producing optical interconnects on 6096 $ast ,$ 6096 mm large-area panels is demonstrated Stepwise projection patterning from 1016 $ast ,$ 1016 mm masks has generated optical waveguide patterns over the whole panel using large-area projection lithography equipment The waveguide routing design allows optical waveguides on different 1016 $ast ,$ 1016 mm tiles to be interconnected Four different waveguide connecting geometries in the border region between tiles have been fabricated and tested Multimode waveguides from inorganic-organic hybrid polymers (ORMOCER) (cross section: $le hbox 50~muhbox mast hbox 10~muhbox m$ ) with refractive index step between core and cladding $Delta n=hbox 001$ were produced The index step was adjusted by mixing two diffrent ORMOCER systems The materials show good adhesion to numerous substrates, such as glass and silicon Application concepts such as flexible manufacturing of optoelectrical hybrid backplanes with two-dimensional interconnect, a three-dimensional optical interconnect with optical vias, and a hybrid backplane with the optical interconnect in a strip-format on a separate plane right above the electrical plane are proposed Promising new technologies are presented along with preliminary demonstrativ viability

Polymer Optical Interconnects&#8212;A Scalable Large-Area Panel Processing Approach

Optical devices with micro- and nanooptical elements using polymers and, in particular nano-scaled organic–inorganic hybrid materials such as ORMOCER®s, will be beyond of the next generation of optical components. For the generation of photonic elements, 3D photonic bandgap materials have been proposed as the basis of many devices. In order to create complete 3D photonic bandgaps, materials enabling high refractive index contrast are needed. Combining suitable materials with highly sophisticated processing methods such as two-photon polymerization (2PP) using femtosecond lasers is a step towards novel photonic elements. The materials and the patterning process will be discussed with respect these applications. In order to demonstrate the potential of the 2PP method, different classes of materials are investigated. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Investigations on the generation of photonic crystals using two‐photon polymerization (2PP) of inorganic–organic hybrid polymers with ultra‐short laser pulses

Recent progress in three-dimensional microstructuring of photosensitive materials by femtosecond lasers has been reviewed. Due to the nonlinear nature of multiphoton laser-activated processing, application of ultrashort laser systems allows one to overcome the diffraction limit and to produce high-quality 3D microstructures with a subwavelength resolution. This is very powerful technology with many potential applications which have been briefly discussed in this chapter.

https://link.springer.com/content/pdf/10.1007%2F978-0-387-30453-3_6.pdf

Ruth Houbertz

Papers

Femtosecond laser-induced two-photon polymerization of inorganic-organic hybrid materials for applications in photonics.

Inorganic–Organic Hybrid Polymers for Information Technology: from Planar Technology to 3D Nanostructures

Polymer Optical Interconnects—A Scalable Large-Area Panel Processing Approach

Investigations on the generation of photonic crystals using two‐photon polymerization (2PP) of inorganic–organic hybrid polymers with ultra‐short laser pulses

Three Dimensional Material Processing with Femtosecond Lasers

Ruth Houbertz

Papers

Femtosecond laser-induced two-photon polymerization of inorganic-organic hybrid materials for applications in photonics.

Inorganic–Organic Hybrid Polymers for Information Technology: from Planar Technology to 3D Nanostructures

Polymer Optical Interconnects&#8212;A Scalable Large-Area Panel Processing Approach

Investigations on the generation of photonic crystals using two‐photon polymerization (2PP) of inorganic–organic hybrid polymers with ultra‐short laser pulses

Three Dimensional Material Processing with Femtosecond Lasers

Polymer Optical Interconnects—A Scalable Large-Area Panel Processing Approach