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In this paper, we present the main results of the numerical calculation of the bound states in the continuum (BICs) application in the refractive index (RI) sensing. We consider two types of one-dimensional rectangular photonic structure at subwavelength regime and study the Fano resonance shift for off-Γ BIC. The results obtained will make it possible to create photonic structures for biosensing, for which a high-Q resonance is observed at nonzero incidence angles. [ABSTRACT FROM AUTHOR]

In addition to vital functions, more subsidiary functions are being expected from wearable devices. The wearable technology thus far has achieved the ability to maintain homeostasis by continuously monitoring physiological signals. The quality of life improves if, through further developments of wearable devices to detect, announce, and even control unperceptive or noxious signals from the environment. Soft materials based on photonic engineering can fulfil the abovementioned functions. Due to the flexibility and zero-power operation of such materials, they can be applied to conventional wearables without affecting existing functions. The achievements to freely tailoring a broad range of electromagnetic waves have encouraged the development of wearable systems for independent recognition/manipulation of light, pollution, chemicals, viruses and heat. Herein, the role that photonic engineering on a flexible platform plays in detecting or reacting to environmental changes is reviewed in terms of material selection, structural design, and regulation mechanisms from the ultraviolet to infrared spectral regions. Moreover, issues emerging with the evolution of the wearable technology, such as Joule heating, battery durability, and user privacy, and the potential solution strategies are discussed. This article provides a systematic review of current progress in wearable devices based on photonic structures as well as an overview of possible ubiquitous advances and their applications, providing diachronic perspectives and future outlook on the rapidly growing research field of wearable technology. [ABSTRACT FROM AUTHOR]

We present the results of investigation of conditions leading to optimization of an optical recording medium based on photosensitive urethane–acrylate nanocomposites containing silicone oxide nanoparticles that is used for efficient recording of Bragg gratings by means of multiple-beam interference. It is demonstrated that the choice of most efficient monomers and their concentration in the nanocomposite depending on their structure and the rate of polymerization, followed by finding optimal intensity of recording radiation for given composition, allows regulating the conditions for component diffusion thereby optimizing their redistribution in the recording medium and formation of regions with different values of refractive index. The results of the study can be used for creation of complex 2D and 3D photonic structures based on purposeful modification of light-sensitive polymer nanocomposites exhibiting various properties (luminescent, nonlinear-optical, etc.) [ABSTRACT FROM AUTHOR]

Undesired reflection caused by impedance mismatch can lead to significant power loss and other unwanted effects. In the terahertz regime, anti-reflection method has evolved from simple quarter-wave antireflection coating to sophisticated metamaterial device and photonic structures. In this paper, we examined and compared the theories and techniques of several antireflection implementations for terahertz waves, with emphasis on gradient index photonic structures. A comprehensive study is presented on the design, fabrication and evaluation of this new approach. [ABSTRACT FROM AUTHOR]

The wide band gap of complex oxides is one of the major obstacles limiting their use in photovoltaic cells. To tune the bandgap of complex oxides, nano-sized bismuth titanate-based powders were synthesized by conventional solid reaction method. X-ray diffraction patterns confirmed that all powders were crystallized in an orthorhombic structure. The photoluminescence signal shows that there was no contribution to the optical bandgap from unwanted oxygen vacancy. The UV-vis absorption spectra of LaCo-BiT powder showed that the optical bandgap drastically decreased from 3.1eV to 2.5eV, while those of of BiT and La-BiT showed change in the optical bandgap. From these observations, we could experimentally confirm that cobalt atoms were responsible for the modification of the electronic structure in BiT-based oxides. This approach to controlling the bandgap could be applied to other complex oxides materials, such as other types of Aurivillius phase materials for use in emerging oxide optoelectronic and energy applications. [ABSTRACT FROM AUTHOR]

By incorporating Mg and Y into SrSiON:Eu phosphor, we intended to improve the relatively high thermal quenching and poor efficiency of emission in conventionalSrSiON:Eu phosphors. MSiON:Eu (M = Sr, Mg, Y) compounds were synthesized by ahigh-temperature solid-state reactionand were characterized using X-ray power diffraction as well as excitation and emission spectroscopy. As compared to the pure SrSiON:Eu, the emission intensity of the new MSiON:Eu (M = Sr, Mg, Y) compound was increased by 65 %. Meanwhile, it was also possible to improve the ratio of thermal quenching up to 88 % by substituting the Sr with Mg and/or Y in the SrSiON:Eu crystal structure. This improvement was mainly due to the intrinsic electronic negativity and size effect of Y, which leads to the shrinkage of the O/N ratioand the relaxation of local strain around the Eu ion in the (SrMgY)SiON:Eu structure. Consequently, the (SrMg)SiON:Eu phosphor is expected to be useful as a novel conversion phosphor with high thermal stability for white-light LEDs. [ABSTRACT FROM AUTHOR]