Broadband Absorbers and Selective Emitters based on Plasmonic Brewster Metasurfaces

We discuss the possibility of realizing utlrabroadband omnidirectional absorbers and angularly selective coherent thermal emitters based on properly patterned plasmonic metastructures. Instead of relying on resonant concentration effects that inherently limit the bandwidth, we base our design on the combination of two inherently nonresonant effects: plasmonic Brewster funneling and adiabatic plasmonic focusing. With this approach, we demonstrate compact, broadband absorption and emission spanning terahertz, infrared and optical frequencies, ideal for various energy and defense applications.Comment: 20 pages, 7 figure

Non-paraxial beam propagation in nonlinear optical waveguides using complex Jacobi iteration

Abstract-We present the recently introduced beam propagation method using complex Jacobi iteration adapted for efficient modeling of non-paraxial beam propagation in nonlinear optical waveguides

Broadband Brewster transmission through 2D metallic gratings

Recently, we have introduced a mechanism to achieve ultrabroadband light funnelling and total transmission through 1D narrow metallic gratings at a specific incidence angle, the so-called plasmonic Brewster angle. This phenomenon is based on impedance matching between the guided modes supported by ultranarrow linear slits and transverse-magnetic waves at oblique incidence. In this paper, we demonstrate that such phenomenon, representing the equivalent of Brewster transmission for plasmonic screens, can also occur in 2D metallic gratings of various structural forms and shapes, and that it may be made insensitive to the azimuthal, or polarization, angle u. This finding may have relevant implications to realize large funneling, absorption and squeezing of light in perforated metallic screens

Comparative Assessment of Time-Domain Models of Nonlinear Optical Propagation

ABSTRACT We present a comparative assessment of time-domain approaches for modelling nonlinear optical propagation, focussing on a finite-difference time-domain beam propagation method (TD-BPM) and the rigorous transmission line modelling (TLM) method. The assessment is carried out on the basis of reflection and transmission of non-stationary light beams propagating through the junction of linear and nonlinear waveguides. INTRODUCTION The availability of laser sources generating high-intensity femtosecond optical pulses has recently inspired tremendous research interest in the study and elaboration of novel guiding structures and materials for nonlinear optics applications. In order to study the spatiotemporal dynamics of femtosecond laser pulses propagating in a Kerr-type nonlinear medium, various treatments have been proposed including those based on the generalized nonlinear Schrodinger equation (GNLSE), the finite-difference time-domain (FDTD) method and the transmission line modelling (TLM) method The FDTD and TLM methods are well-known rigorous time-domain techniques providing reliable conduits for comparisons. The main difference between these two widely used time-domain techniques is the layout of the time-stepping and the unit cell process. In the TLM method, the fields are solved at the same time instant at the centre of the TLM cell resulting in a straightforward solution of nonlinear equations, whereas in the FDTD method there is a separation of half a space step and half a time step between the electric and magnetic fields. However, these methods require a very small time step size to fulfil the stability criterion; this leads to a substantial increase in the computation resources required, especially for the analysis of long lengths of optical waveguides. Recently, simple and efficient BPMs in the time domain have been develope

Enhanced Near-Infrared Fluorescent Sensing Using Metal-Dielectric-Metal Plasmonic Array

This work presents a numerical study of metal-dielectric-metal (MDM) plasmonic structure used to enhance a near-infrared fluorescent sensor. The MDM plasmonic structure consists of silver (Ag) subwavelength disk arrays on a thin silica (SiO2) spacing layer and 100-nm-thick-Ag film on a silicon (Si) substrate. The MDM plasmonic arrays with various structural parameters are designed and numerically investigated using the finite-difference time-domain (FDTD) method. Results show that the optical properties of designed structures are slightly dependent on the height of the Ag disk and strongly dependent on the Ag disk diameter and SiO2 thickness. In the near-infrared wavelength range, the proposed MDM plasmonic array has low ohmic loss and shows the high fluorescent emitting enhancement and directivity of about 16 times and 625.0, respectively, thus making MDM plasmonic array an alternative approach for near-infrared fluorescence bioimaging and biosensing devices