Hybrid materials for optics and photonics

The interest in organic-inorganic hybrids as materials for optics and photonics started more than 25 years ago and since then has known a continuous and strong growth. The high versatility of sol-gel processing offers a wide range of possibilities to design tailor-made materials in terms of structure, texture, functionality, properties and shape modelling. From the first hybrid material with optical functional properties that has been obtained by incorporation of an organic dye in a silica matrix, the research in the field has quickly evolved towards more sophisticated systems, such as multifunctional and/or multicomponent materials, nanoscale and self-assembled hybrids and devices for integrated optics. In the present critical review, we have focused our attention on three main research areas: passive and active optical hybrid sol-gel materials, and integrated optics. This is far from exhaustive but enough to give an overview of the huge potential of these materials in photonics and optics (254 references).     

Organometallic materials for nonlinear optics

Almost three decades ago, the field of nonlinear optics evolved with the discovery of lasers. In the beginning, nonlinear optical (NLO) phenomena were investigated in inorganic materials, leading to the development of traditional NLO materials such as lithium niobate, potassium titanyl phosphate, quartz and gallium arsenide. In the 1970s, the importance of organic materials was realized because of the promise of large NLO responses, high laser damage thresholds, fast optical responses, architectural flexibility and ease of fabrication. Following work with organic materials, the scrutiny of organometallics also began recently. In organometallics, the metal-ligand bonding is expected to display large molecular hyperpolarizability because of the transfer of electron density between the metal atom and the conjugated ligand system. In organometallics, the diversity of central metals, oxidation states and ligands fosters in optimization of the charge-transfer interactions. Keeping this in view, second- and third-order NLO properties of organometallics have been reviewed here, highlighting new materials that are emerging. Organometallics may have a wide range of applications in opto-electronics including integrated optics, optical switching, telecommunications, bistability and modulation.     

Organic Polymeric and Non-Polymeric Materials with Large Optical Nonlinearities

Nonlinear optical properties are a sensitive probe of the electronic and solid-state structure of organic compounds and as a consequence find various applications in many areas of optoelectronics including optical communications, laser scanning and control functions, and integrated optics technology. Because of their strongly delocalized π electronic systems, polymeric and non-polymeric aromatic compounds show highly nonlinear optical effects. Nowadays, polymer chemists are able to tailor specific materials properties for various applications. Some organic substances with π electronic systems exhibit the largest known nonlinear coefficients, often considerably larger than those of the more conventional inorganic dielectrics and semiconductors, and thus show promise for thin-film fabrication, allowing the enormous function and cost advantages of integrated electronic circuitry. The electronic origins of nonlinear optical effects in organic π electronic systems are reviewed, with special emphasis being given to second-order nonlinear optical effects. Methods for measuring nonlinear optical responses are outlined, and the critical relationships of the propagation characteristics of light to observed nonlinear optical effects and to solid-state structure are discussed. Finally, the synthesis and characterization of organic crystals and polymer films with large second-order optical nonlinearities are summarized.     

自愈合聚合物材料的研究进展Ⅱ.热塑性聚合物的自愈合机理

自愈合聚合物材料是受自我修复生物体系的触发而发展的,这是一个新兴迷人的研究领域,可以明显拓宽聚合物材料的工作寿命和广泛应用的安全性.文章是《自愈合聚合物材料的研究进展Ⅰ.传统修复方法及热固性自愈合材料的制备和表征》的续篇,进一步介绍可自我修复的热塑性高分子材料的愈合机理.     

稀土/L型沸石主-客体发光功能材料的研究进展

沸石微孔晶体材料作为客体功能物种的主体材料在主-客体组装化学中发挥着越来越重要的作用,在微型激光器、非线性光学、生物成像、光放大及光显示等高技术领域已显示出广阔、诱人的发展前景.本文介绍国内外,特别是河北工业大学在稀土/L型沸石主-客体杂化功能材料的组装、结构及其发光性能的研究工作,具体包括：稀土有机配合物在L沸石孔道内的组装、L型沸石-有机高分子透明杂化发光材料的制备及稀土有机配合物诱导控制的L型沸石自组装等.此外,本文对稀土/L型沸石主-客体杂化发光功能材料的研究进行了展望.     

自愈合聚合物材料的研究进展Ⅰ.传统修复方法及热固性自愈合材料的制备和表征

自愈合聚合物材料是受自我修复生物体系的触发而发展的,这是一个新兴迷人的研究领域,可以明显拓宽聚合物材料的工作寿命和广泛应用的安全性.参考近年来的文献资料,文章着重介绍了传统的修复聚合物材料的方法,以及各种热固性自愈合材料的制备和表征,其中最主要的制备方法是中空纤维法和微胶囊法.     

High-refractive index acrylate polymers for applications in nanoimprint lithography

The development of polymeric optical materials with a higher refractive index,transparency in the visible spectrum region and easier processability is increasingly desirable for advanced optical applications such as microlenses,image sensors,and organic light-emitting diodes.Most acrylates have a low refractive index(around 1.50)which does not meet the high perfo rmance requirements of advanced optical materials.In this research,three novel acrylates were synthesized via a facile one-step approach and used to fabricate optical transparent polymers.All of the polymers reveal good optical properties including high transparency(≥90%)in the visible spectrum region and high refractive index values(1.6363)at 550 nm.Moreover,nanostructures of these acrylate polymers with various feature sizes including nanogratings and photonic crystals were successfully fabricated using nanoimprint lithography.These results indicate that these acrylates can be used in a wide range of optical and optoelectronic devices where nanopatterned films with high refractive index and transparency are required.     

Real-time PCR in a plastic chip based on solid state FRET

We show a novel solid state optical detection platform, integrated in a plastic biochip, based on colloidal nanocrystal FRET donors. The approach exploits a "smart" polymeric layer with both optical and biorecognition properties that allows real-time monitoring of biomolecular interactions and quantitative analyses of real-time PCR. The proposed strategy, demonstrated here for DNA detection, may open interesting perspectives for a wide range of applications, such as for proteomic studies.     

Visible Light-Driven Molecular Switches and Motors: Recent Developments and Applications

Inspired by human vision, a diverse range of light-driven molecular switches and motors have been developed for fundamental understanding and application in material science and biology. Recently, the design and synthesis of visible light-driven molecular switches and motors have been actively pursued. This emerging trend is partly motivated to avoid the harmful effects of ultraviolet light, which was necessary to drive the classical molecular switches and motors at least in one direction, impeding their employment in biomedical and photopharmacology applications. Moreover, visible light-driven molecular switches and motors are demonstrated to enable benign optical materials for advanced photonic devices. Therefore, during the past several years, visible light-driven molecular switches based on azobenzene derivatives, diarylethenes, 1,2-dicyanodithienylethenes, hemithioindigo derivatives, iminothioindoxyls, donor-acceptor Stenhouse adducts, and overcrowded alkene based molecular motors have been judiciously designed, synthesized, and used in the development of functional materials and systems for a wide range of applications. In this Review, we present the recent developments toward the design of visible light-driven molecular switches and motors, with their applications in the fabrication of functional materials and systems in material science, bioscience, pharmacology, etc. The visible light-driven molecular switches and motors realized so far undoubtedly widen the scope of these interesting compounds for technological and biological applications. We hope this Review article could provide additional impetus and inspire further research interests for future exploration of visible light-driven advanced materials, systems, and devices.     

Sol–gel thin films for optics and photonics

Thin films have wide applications in the area of optics and photonics. Conventional thin film processing is usually followed for deposition, but the sol–gel route is unique as it can be applied very easily in a cost effective way on desired substrates of any shape for specific applications. In this review, the basic optical designs of antireflection, high reflection, different types of optical filters, coloured coatings, etc. have been discussed with some typical examples of sol–gel products. The importance of coloured coatings and low thermal emissivity coatings on window glass has also been highlighted. In addition, the use of sol–gel processing for different types of film formation which are effective for photonic applications such as non-linearity in optics, ferromagnetism in transparent dilute magnetic semiconductors (DMS), generation of quantum dots as phosphor, grating coupler waveguide in optical sensors are discussed. The basic characterizations of a few sol–gel products which may be used for photonic applications have also been highlighted.     

The good,the bad,and the tiny: a review of microflow cytometry

Recent developments in microflow cytometry have concentrated on advancing technology in four main areas: (1) focusing the particles to be analyzed in the microfluidic channel, (2) miniaturization of the fluid-handling components, (3) miniaturization of the optics, and (4) integration and applications development. Strategies for focusing particles in a narrow path as they pass through the detection region include the use of focusing fluids, nozzles, and dielectrophoresis. Strategies for optics range from the use of microscope objectives to polymer waveguides or optical fibers embedded on-chip. While most investigators use off-chip fluidic control, there are a few examples of integrated valves and pumps. To date, demonstrations of applications are primarily used to establish that the microflow systems provide data of the same quality as laboratory systems, but new capabilities-such as automated sample staining-are beginning to emerge. Each of these four areas is discussed in detail in terms of the progress of development, the continuing limitations, and potential future directions for microflow cytometers.     

Advances in Photonic Devices Based on Optical Phase-Change Materials

Phase-change materials (PCMs) are important photonic materials that have the advantages of a rapid and reversible phase change, a great difference in the optical properties between the crystalline and amorphous states, scalability, and nonvolatility. With the constant development in the PCM platform and integration of multiple material platforms, more and more reconfigurable photonic devices and their dynamic regulation have been theoretically proposed and experimentally demonstrated, showing the great potential of PCMs in integrated photonic chips. Here, we review the recent developments in PCMs and discuss their potential for photonic devices. A universal overview of the mechanism of the phase transition and models of PCMs is presented. PCMs have injected new life into on-chip photonic integrated circuits, which generally contain an optical switch, an optical logical gate, and an optical modulator. Photonic neural networks based on PCMs are another interesting application of PCMs. Finally, the future development prospects and problems that need to be solved are discussed. PCMs are likely to have wide applications in future intelligent photonic systems.     

非硅基介孔材料和介孔复合体的合成与特性

非硅基介孔材料和介孔复合体的合成与特性;介孔固体;介孔复合体;二氧化钛薄膜;液晶模板机理     

Thermo-optic coefficient of polyisobutylene ultrathin films measured with integrated photonic devices

The optical properties of polymeric materials, such as transmission loss and the thermo-optic coefficient, determine their utility in numerous applications, ranging from nanotechnology to the automotive and aerospace industries. However, because of the wide variation in the physical properties of polymers, many are unsuited for characterization using conventional techniques; consequently, their optical properties are unknown. One such polymer is polyisobutylene, which is viscous at room temperature and therefore is not compatible with conventional transmission loss and the thermo-optic coefficient characterization techniques because they rely on contact measurements. To overcome this, we have developed an integrated, microscale optical sensor that relies on an evanescent wave to study the material's optical behavior. Using this device, we successfully determined the refractive index, the transmission loss, and the thermo-optic coefficient of ultrathin films of polyisobutylene. The films are deposited on the sensor's silica surface using either spin coating or surface-initiated cationic polymerization, demonstrating the flexibility of this approach.     

稀土无机发光材料:电子结构、光学性能和生物应用

目前,稀土无机发光材料在激光、光通讯、平板显示、荧光生物标记和纳米光电子器件等领域具有广泛的应用前景.稀土离子(从Ce到Yb)是一类性能优异的结构和光谱探针,其在不同介质材料中的光学性能主要取决于其局域态的电子结构和激发态动力学.对稀土发光材料开展深入的光学和光电子学基础研究有助于发现新颖的光学性能或开辟新的应用领域.依托研制的低温高分辨激光光谱和上转换量子产率等仪器,本课题组致力于稀土无机发光材料电子结构与性能研究,近年来在发光材料的控制合成、电子结构、光学性能及生物应用等方面取得了系列重要结果.这些研究有望加快实现稀土无机发光材料在生物应用的突破,实现稀土资源的高值利用.     

Recent progress in conductive polymeric materials for biomedical applications

Advanced polymeric materials undoubtedly constitute one of the most promising classes of new materials due to their intriguing electronic, optical, and redox properties. The incredible progress in this area has been driven by the development of novel synthetic procedures owing to the emergence of nanotechnology and by the large array of applications. In particular, hybridization of polymeric materials with nanomaterials has allowed the production of promising functional materials with tailored properties and functionalities for targeted biomedical applications. Consequently, sufficient researchers have carried out imperative studies on these advanced polymeric materials over the last decade. Beyond scientific and fundamental interest, such advanced materials are conspicuous from technological perspectives as well. In this review, we accentuate the proliferation of advanced polymeric materials in diverse biomedical applications.     

Controlling polymer properties through dynamic metal-ligand interactions: supramolecular cruciforms made easy

A straightforward methodology towards the supramolecular synthesis of novel organometallic polymers with attractive optical properties is presented. By coordinating bifunctional fluorescent cruciform molecules through ditopic metalated pincer complexes (Pd or Pt), we have synthesized a new class of well-defined coordination polymers that have controllable and tunable physical and photophysical properties. The formation of these new materials by employing metal coordination was monitored by (1)H NMR spectroscopy, the association strength of the metal-ligand interaction was measured by isothermal titration calorimetry, the solution polymeric properties were evaluated by viscometry, and the optical properties were measured and observed by fluorescence spectroscopy. The fast and quantitative synthesis of a wide range of prefabricated monomeric cruciform and metalated-pincer-complex components will allow for the rapid generation, growth, and optimization of this new class of functional polymers, which have potential electronic and optical applications.     

硅酸镓镧族非线性光学晶体

中红外非线性光学晶体可以实现中红外激光频率转换、拓展激光波长,在民用和军用领域中有至关重要的应用价值。其中,硅酸镓镧族晶体具有透过范围宽、激光损伤阈值高、晶体质量好等优势,引起了国内外同行的广泛关注。在这篇综述中,我们基于现有的实验数据,研究和分析了三种重要的硅酸镓镧族晶体La_3Ga_5Si O_(14)(LGS)、La_3Ga_(5.5)Nb_(0.5)O_(14)(LGN)、La_3Ga_(5.5)Ta_(0.5)O_(14)(LGT)的综合性能,详细总结了它们在电光调Q开关和中红外光参量振荡以及差频激光输出方面的应用。最后,本文还讨论了今后硅酸镓镧族中红外非线性光学晶体的重点发展方向。     

Multidirectional Wrinkle Patterns Programmed by Sequential Uniaxial Strain with Conformal yet Nontraceable Masks

Surface wrinkling is a promising route to control the mechanical, electrical, and optical properties of materials in a wide range of applications. However, previous artificial wrinkles are restricted to single or random orientation and lacks selectivity. To address this challenge, this study presents multidirectional wrinkle patterns with high selectivity and orientation through sequential uniaxial strain with conformal polymeric shadow masks. The conformal but nontraceable polymeric stencil with microapertures are adhered to a flat substrate prior to oxidation, which forms discrete and parallel wrinkles in confined domains without any contamination. By fully investigating the process, this study displays compound topography of wrinkles consisting of wrinkle islands and surrounding secondary wrinkles on the same surface. With this topography, various diffusion properties are presented: from semi‐transparent yet diffusive films to multidirectional diffusive films, which will be available for new types of optical diffuser applications.