Materials for freezing light

Recent theoretical investigations have predicted the existence of axially frozen modes that arise when light is incident upon an anisotropic two-dimensional photonic crystal. Such electromagnetic modes are of interest since they suggest a near-zero group velocity with extraordinary amplitudes. The present invention addresses the crystal physics associated with realizing such effects and provides for the development of materials suitable for use in the forming photonic crystals that can exhibit such effects

Frozen light in periodic stacks of anisotropic layers

We consider a plane electromagnetic wave incident on a periodic stack of dielectric layers. One of the alternating layers has an anisotropic refractive index with an oblique orientation of the principal axis relative to the normal to the layers. It was shown recently (A. Figotin and I. Vitebskiy, Phys. Rev. E68, 036609 2003) that an obliquely incident light, upon entering such a periodic stack, can be converted into an abnormal axially frozen mode with drastically enhanced amplitude and zero normal component of the group velocity. The stack reflectivity at this point can be very low, implying nearly total conversion of the incident light into the frozen mode with huge energy density, compared to that of the incident light. Supposedly, the frozen mode regime requires strong birefringence in the anisotropic layers - by an order of magnitude stronger than that available in common anisotropic dielectric materials. In this paper we show how to overcome the above problem by exploiting higher frequency bands of the photonic spectrum. We prove that a robust frozen mode regime at optical wavelengths can be realized in stacks composed of common anisotropic materials, such as YVO₄, LiNb, CaCO₃, and the like.Comment: to be submitted to Phys. Rev.

Network Formalism for Modeling Functionally Gradient Piezoelectric Plates and Stacks and Simulations of RAINBOW Ceramic Actuators

A simple network representation is given for a stack of thin, homogeneous piezoelectric plates, executing a single thickness mode of motion. All plates may differ in thickness and material properties, including dielectric loss, ohmic conductivity, and viscous loss. Each plate is driven by a thickness-directed electric field, and all stack elements are connected electrically in series. Functionally gradient single plates and composites are readily modeled by the network, to a desired precision, using a sequence of circuit elements representing stepwise variations in material properties and layer thicknesses. Simulations of RAINBOW (reduced and internally biased oxide wafer) ceramics are given

Towards the Perfect Optical Fiber

Optical fibers are being used in an ever more diverse array of applications today. Many of these modern applications are in high-power and, particularly, high power-per-unit-bandwidth systems where optical nonlinearities historically have not limited overall performance. Today, however, nominally weak effects, such as stimulated Brillouin scattering (SBS), are restricting continued scaling to higher optical powers. To address these limitations, the optical fiber industry has focused on fiber geometry-related solutions such as large mode area (LMA) designs. However, since all linear and nonlinear optical phenomena are fundamentally materials-based in origin, this paper identifies material solutions to present and future performance limitations in high power optical fiber-based systems

Terahertz Waveguiding in Silicon-Core Fibers

We propose the use of a silicon-core optical fiber for terahertz (THz) waveguide applications. Finite-difference time-domain simulations have been performed based on a cylindrical waveguide with a silicon core and silica cladding. High-resistivity silicon has a flat dispersion over a 0.1 - 3 THz range, making it viable for propagation of tunable narrowband CW THz and possibly broadband picosecond pules of THz radiation. Simulations show the propagation dynamics and the integrated intensity, from which transverse mode profiles and absorption lengths are extraced. It is found that for 140 - 250 micron core diameters the mode is primarily confined to the core, such that the overall absorbance is only slightly less than in bulk polycrystalline silicon.Comment: 6 pages, 3 figures, journal submissio

Properties of GaP Studied over 50 Years

A unique set of GaP semiconductor samples studied for over 50 years has exhibited significant improvement in their properties through the formation of the perfect host crystal lattice and the N‐impurity crystal superlattice. This chapter reviews this evolution of properties and discusses their novel utility in advanced optoelectronic devices. More specifically, nitrogen‐doped gallium phosphide (GaP:N) crystals that were originally prepared in the 1960s were theorized to form an excitonic crystal (1970s), and the best methods of their bulk, film, and nanoparticle crystal growth have subsequently been developed. The excitonic crystals yield novel and useful properties including enhanced stimulated emission and very bright and broadband luminescence at room temperature, which have been observed. These results provide a new approach to the selection and preparation of “perfect” materials for optoelectronics and offer a unique opportunity to realize a new form of solid‐state host—the excitonic crystal—as a high‐intensity light source with low thresholds for nonlinear optical effects

Feature issue introduction: specialty optical fibers

For groundbreaking achievements concerning the transmission of light in fibers for optical communication. With this citation, the Nobel Committee bestowed the 2009 Nobel Prize in Physics to Dr. Charles Kao and validated the global importance of optical fibers. That said, technological demands march on and the applications in which optical fibers are employed continue to expand. Further, both existing and emerging applications are requiring greater performance and functionality, beyond those associated with telecommunications, from the enabling optical fibers; and so it is timely to offer this special issue that compiles recent advances in specialty optical fibers