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

In the real world, a realistic setting for computer vision or multimedia recognition problems is that we have some classes containing lots of training data and many classes contain a small amount of training data. Therefore, how to use frequent classes to help learning rare classes for which it is harder to collect the training data is an open question. Learning with Shared Information is an emerging topic in machine learning, computer vision and multimedia analysis. There are different level of components that can be shared during concept modeling and machine learning stages, such as sharing generic object parts, sharing attributes, sharing transformations, sharing regularization parameters and sharing training examples, etc. Regarding the specific methods, multi-task learning, transfer learning and deep learning can be seen as using different strategies to share information. These learning with shared information methods are very effective in solving real-world large-scale problems. This special issue aims at gathering the recent advances in learning with shared information methods and their applications in computer vision and multimedia analysis. Both state-of-the-art works, as well as literature reviews, are welcome for submission. Papers addressing interesting real-world computer vision and multimedia applications are especially encouraged. Topics of interest include, but are not limited to:  • Multi-task learning or transfer learning for large-scale computer vision and multimedia analysis • Deep learning for large-scale computer vision and multimedia analysis • Multi-modal approach for large-scale computer vision and multimedia analysis • Different sharing strategies, e.g., sharing generic object parts, sharing attributes, sharing transformations, sharing regularization parameters and sharing training examples, • Real-world computer vision and multimedia applications based on learning with shared information, e.g., event detection, object recognition, object detection, action recognition, human head pose estimation, object tracking, location-based services, semantic indexing. • New datasets and metrics to evaluate the benefit of the proposed sharing ability for the specific computer vision or multimedia problem. • Survey papers regarding the topic of learning with shared information.  Authors who are unsure whether their planned submission is in scope may contact the guest editors prior to the submission deadline with an abstract, in order to receive feedback.

IEEE transactions on pattern analysis and machine intelligence

Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201707035

Soft Robotic Grippers.

Finite element methods for Maxwell's equations.

Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials,...

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Circuit Modeling of Discontinuous Planar Waveguides at High Frequencies

This paper considers the application of the Generalized Telegraphers Equations (GTE) to the electromagnetic modelling and designing of integrated electro-optical devices. This approach allows to eliminate the restrictions introduced by others models, as: weakly guiding condition and isotropic unperturbed medium and to value the modulator time response for a generic modulating signal. The presence of small dielectric perturbations and the large difference between the optical and modulating signal frequencies are the hypotheses considered in deriving the model. The analysis has been applied to a GaAs phase modulator in order to validate the equations and to evidence the effects of the induced anisotropy on the time-domain response. The model can be extended to the analysis of multimode dielectric waveguides, such as independent polarization and directional coupler modulator. Keywords: Electro-optic modulation, anisotropic waveguide, Telegraphers Equations. 1. INTRODUCTION The development of high-speed digital transmission systems (high rates Time Domain Multiplexing systems) are stimulating a renewed demand for broad band optical devices [2], where electro-optic devices have a considerable role [2]. In this work we analyze, by means of a novel and rigorous approach, the effect induced by a microwave field on a propagating optical signal; the microwave field modulates the refractive index of the dielectric waveguide. The theory of electro-optic traveling wave modulator has been widely considered in the past. The theoretical approach of [1] is based on the fact that the modulating field induces coupling between the optical propagating modes; in order to obtain an analytical solution, a slowly varying envelope along the propagation direction and an isotropic medium in absence of modulating field, are assumed. The theory of the electro-optic modulation can also be derived by means of an improved coupled mode theory, as in [3], where the model is applied to an arbitrary anisotropic dielectric waveguide, under some constraints on the propagating constants and on the longitudinal optical field components. The model presented in this paper starts from Maxwells equations in order to derive the Generalized Telegraphers Equations for a time and space varying anisotropic media. Small dielectric variations on the permittivity tensor are assumed (

On the use of generalized telegrapher’s equations in the synthesis of electro-optic modulators

Reconfigurability in an antenna system is a desired characteristic that has attracted of attention in the past years. In this work, a novel class of nonconformal Fermat-like spiral multi-port microantennas for next-generation wireless communications and radar applications is presented. The device modeling is carried out by using a computationally enhanced locally conformal finite-difference time-domain full-wave procedure. In this way, the circuital characteristics and radiation properties of the antennas are investigated accurately. The structure reconfigurability, in terms of frequency of operation and radiation efficiency, is technically performed by a suitable solid-state tuning circuitry adopted to properly change the feeding/loading conditions at the antenna input ports.

Reconfigurable nonconformal spiral microantenna for wireless communication devices

Atomic clusters (TiO2)n are studied by means of state of the art techniques for structural, electronic and optical properties. We combine molecular dynamics, density functional theory and time dependent density functional theory to provide a deep and comprehensive characterization of the system. Atomic clusters can be considered the starting seeds for the synthesis of larger nanostructures of technological interest. Also, given the complexity of the material itself, a clear theoretical description of its basic properties provides interesting results both from the solid state physics and chemistry point of view.

Alessandro Massaro

Papers

Circuit Modeling of Discontinuous Planar Waveguides at High Frequencies

On the use of generalized telegrapher’s equations in the synthesis of electro-optic modulators

Reconfigurable nonconformal spiral microantenna for wireless communication devices

Characterization of TiO2 atomic crystals for nanocomposite materials oriented to optoelectronics

The Determinants of Internet User Skills in Europe