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As a novel optical responsive material, photonic crystal is a promising sensing material in the recognition and detection of small molecules. Herein, a label-free composite sensor for aflatoxin B1 (AFB1) based on aptamer-functionalized photonic crystal arrays was successfully developed. Three-dimensional photonic crystals (3D PhCs) with a controllable number of layers were produced by a layer-by-layer (LBL) approach, and the introduction of gold nanoparticles (AuNPs) facilitated the immobilization procedure of recognition element aptamers, thus creating the AFB1 sensing detection system (AFB1-Apt 3D PhCs). The sensing system AFB1-Apt 3D PhCs exhibited a good linearity in the wide range of 1 pg mL−1-100 ng mL−1 AFB1 with a limit of detection (LOD) of 0.28 pg mL−1. Furthermore AFB1-Apt 3D PhC was successfully applied in the determination of AFB1 in the millet and beer samples with good recovery. The sensing system performed ultrasensitive and label-free detection to the target, which could be further applied in the fields of food safety, clinical diagnosis or environmental monitoring, establishing an efficient and rapid universal detection platform. [Display omitted] • A 3D photonic crystals (PhCs) aptamer sensing for ultrasensitive label-free detection of AFB1. • 3D PhCs with a controllable number of layers were produced by a layer-by-layer approach. • The introduction of Au NPs into PhCs increase the optical signal response. • The AFB1-Apt 3D PhCs exhibited extreme LOD (0.28 pg mL−1) for AFB1. • High selectivity and anti-interference ability in AFB1 detection in beer and millet. [ABSTRACT FROM AUTHOR]

In order to achieve compatible stealth via VO 2 in visible and near-infrared bands, the SiO 2 -VO 2 films with desired structural colors and thermochromic properties were successfully prepared based on three-dimensional photonic crystal (3DPC) structure of SiO 2 templates. It is found that with the varying diameters of SiO 2 spheres, the SiO 2 -VO 2 films appear beautiful red, green, and blue color, respectively. The SiO 2 -VO 2 films keep the same structural color with SiO 2 3DPC templates and the good thermochromic properties of VO 2. In addition, the reflectivity of the SiO 2 -VO 2 films increased obviously and possessed thermochromic properties in near infrared region when the temperature ranged from 30 °C to 80 °C. The calculation and preparation methods used in this work may provide both theoretical and practical supports for the feasible preparation of SiO 2 -VO 2 films with required colors and thermochromic properties. • The SiO 2 -VO 2 films enrich the color of VO 2 -based materials by varying the particle size of the SiO 2 spheres. • The mechanism and feasibility of enriching the structural color were studied by the theoretical simulation and experiments. • The SiO 2 -VO 2 films with desired structural color possess the good thermochromic properties of VO 2 in near infrared region. [ABSTRACT FROM AUTHOR]

The creation of large-area, unintentional-defect-free three-dimensional (3D) photonic crystals in the optical regime is a key challenge toward the realization of the arbitrary 3D manipulation of photons. In this article, we discuss an advanced fabrication method of 3D silicon photonic crystals based on the highly accurate alignment and wafer bonding of silicon-on-insulator (SOI) wafers. We introduce an advanced alignment system, in which the alignment process is automated by image recognition and feed-back control of stages, and show that it achieves an alignment accuracy better than ~50 nm. The bonding of SOI wafers is also investigated to obtain 3D crystals composed of highly pure crystalline silicon. We show the fabrication results of large-area 3D photonic crystals based on such considerations and demonstrate the successful introduction of artificial defects as functional components, such as coupled waveguide pairs or waveguides/nanocavities. We expect that these will be pioneering results toward the arbitrary 3D control of photons using 3D photonic crystals.

Three-dimensional photonic crystals (3D PhCs) are a fascinating platform for manipulating photons and controlling their interactions with matter. One widely investigated structure is the layer-by-layer woodpile structure, which possesses a complete photonic bandgap. On the other hand, other types of 3D PhC structures also offer various possibilities for controlling light by utilizing the three dimensional nature of structures. In this article, we discuss our recent research into novel types of layer-by-layer structures, including the experimental demonstration of a 3D PhC nanocavity formed in a -layered diamond structure and the realization of artificial optical activity in rotationally stacked woodpile structures.

We report a simple design of high quality-factor ( Q) three-dimensional woodpile photonic crystal (PC) nanocavity with vertically mirror-symmetric structure, which can be realized by changing the stacking order of layers above the cavity layer from ordinary woodpile structures. A Q of 1.7×105 in the mirror-symmetric structure was obtained with a relatively small PC size. This is ∼3.6 times as high as the maximum Q of the same nanocavity embedded in an ordinary woodpile structure of the same PC volume. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: We report experimental and numerical studies of a polarization conversion by a three-dimensional photonic crystal. The (001) surface of a photonic crystal with a diamond structure has been shown to act as a mirror-type polarization convertor under normal incidence. When the direction of the incident wave polarization is along [010], the direction of the reflected wave polarization is converted to [100]. This has been found to be due to approximately a half-wave phase shift between the eigenpolarizations of [110] and upon reflection. This result has been discussed in relation with a polarization-dependent Goos–Haenchen effect. [Copyright &y& Elsevier]

Abstract: A novel hybrid organic–inorganic photocurable sol–gel material based on tantalum ethoxide and 3-trimethoxysilylpropylmethacrylate has been developed, characterised and used in the fabrication of optical waveguides and three-dimensional woodpile structures employing the single and two-photon polymerisation techniques, respectively. Single mode waveguides operating at 1310 and 1550nm have been fabricated, optically characterised and their performances correlated to the material formulation. Three-dimensional woodpile structures exhibiting negligible shrinkage have been developed and their remarkable mechanical stability correlated to the molecular structure of the hybrid material. The overall fabrication process of these devices is described and it is shown that the refractive indices of the materials can be tailored by a precise control of the material composition allowing the successful fabrication of performing single mode waveguides. [ABSTRACT FROM AUTHOR]

An effective tool for accurate analysis and design of a wide range of optical devices involving three-dimensional (3-D) photonic crystals is provided. The advantages of using transverse resonance in conjunction with full-wave numerical solvers in order to characterize this kind of structures are highlighted. This paper focuses on the study of a practical example of an asymmetric crystal slab and shows the features of the proposed method in terms of accuracy and flexibility. The concept of Floquet modes of a periodic crystal is applied, and a multimode transverse equivalent network is developed in the aim of obtaining the resonant 3-D modes of the slab containing the photonic crystal [ABSTRACT FROM PUBLISHER]

This work investigated the phenomena and cause of photonic band gap (PBG) shift under an open environment at −10 °C ∼ 20 °C for the three-dimensional (3D) photonic crystals (PCs). The 3D PCs were composed of polystyrene spheres using the self-assembly method. The reflective gloss of 3D PC sample underwent non-monotonous color change within the temperature region. PBG of PCs first red-shifted during the cooling from room temperature. Later, the PBG blue-shifted when the temperature decreased from about 0 °C. The average transmittance through the PC sample within the visible range also increased first and then decreased with ambient temperature reduction. Influences from structure dimension, optical constants of involved materials, condensation and its phase change on PBG were all quantitatively investigated. • Optical responses of 3D photonic crystals near the freezing point were investigated. • Reflective gloss of samples varied significantly within an open environment. • The bandgap experienced two-stage shifts as the temperature reduced. • Transparency variation was addressed via near-field electromagnetic analysis. • Repeatability of two-stage changes in optical responses was confirmed. [ABSTRACT FROM AUTHOR]