Publications

Abstract not provided.

Abstract not provided.

The role of crystal coherence length on the infrared optical response of MgO thin films was investigated with regard to Reststrahlen band photon-phonon coupling. Preferentially (001)-oriented sputtered and evaporated ion-beam assisted deposited thin films were prepared on silicon and annealed to vary film microstructure. Film crystalline coherence was characterized by x-ray diffraction line broadening and transmission electron microscopy. The infrared dielectric response revealed a strong dependence of dielectric resonance magnitude on crystalline coherence. Shifts to lower transverse optical phonon frequencies were observed with increased crystalline coherence. Increased optical phonon damping is attributed to increasing granularity and intergrain misorientation.

Abstract not provided.

This paper introduces an effective-media toolset that can be used for the design of metamaterial structures based on metallic components such as split-ring resonators and dipoles, as well as dielectric spherical resonators. For demonstration purposes the toolset will be used to generate infrared metamaterial designs, and the predicted performances will be verified with full-wave numerical simulations.

Metamaterials form a new class of artificial electromagnetic materials that provides the device designer with the ability to manipulate the flow of electromagnetic energy in ways that are not achievable with naturally occurring materials. However, progress toward practical implementation of metamaterials, particularly at infrared and visible frequencies, has been hampered by a combination of absorptive losses; the narrow band nature of the resonant metamaterial response; and the difficulty in fabricating fully 3-dimensional structures. They describe the progress of a recently initiated program at Sandia National Laboratories directed toward the development of practical 3D metamaterials operating in the thermal infrared. They discuss their analysis of fundamental loss limits for different classes of metamaterials. In addition, they discuss new design approaches that they are pursuing which reduce the reliance on metallic structures in an effort to minimize ohmic losses.

Abstract not provided.

Abstract not provided.

We present a new fabrication technique called Membrane Projection Lithography for the production of three-dimensional metamaterials at infrared wavelengths. Using this technique, multilayer infrared metamaterials that include both in-plane and out-of-plane resonators can be fabricated.

Dielectric resonators are an effective means to realize isotropic, low-loss optical metamaterials. As proof of this concept, a cubic resonator is analytically designed and then tested in the long-wave infrared.

The authors have developed two versions of a flexible fabrication technique known as membrane projection lithography that can produce nearly arbitrary patterns in '212 D' and fully three-dimensional (3D) structures. The authors have applied this new technique to the fabrication of split ring resonator-based metamaterials in the midinfrared. The technique utilizes electron beam lithography for resolution, pattern design flexibility, and alignment. The resulting structures are nearly three orders of magnitude smaller than equivalent microwave structures that were first used to demonstrate a negative index material. The fully 3D structures are highly isotropic and exhibit both electrically and magnetically excited resonances for incident transverse electromagnetic waves.

Most far-field optical imaging systems rely on a lens and spatially-resolved detection to probe distinct locations on the object. We describe and demonstrate a novel high-speed wide-field approach to imaging that instead measures the complex spatial Fourier transform of the object by detecting its spatially-integrated response to dynamic acousto-optically synthesized structured illumination. Tomographic filtered backprojection is applied to reconstruct the object in two or three dimensions. This technique decouples depth-of-field and working-distance from resolution, in contrast to conventional imaging, and can be used to image biological and synthetic structures in fluoresced or scattered light employing coherent or broadband illumination. We discuss the electronically programmable transfer function of the optical system and its implications for imaging dynamic processes. Finally, we present for the first time two-dimensional high-resolution image reconstructions demonstrating a three-orders-of-magnitude improvement in depth-of-field over conventional lens-based microscopy.

Abstract not provided.

Abstract not provided.

Abstract not provided.

3-D cubic unit cell arrays containing split ring resonators were fabricated and characterized. The unit cells are {approx}3 orders-of-magnitude smaller than microwave SRR-based metamaterials and exhibit both electrically and magnetically excited resonances for normally incident TEM waves in addition to showing improved isotropic response.

Abstract not provided.

We describe a time-domain spectroscopy system in the thermal infrared used for complete transmission and reflection characterization of metamaterials in amplitude and phase. The system uses a triple-output near-infrared ultrafast fiber laser, phase-locked difference frequency generation and phase-matched electro-optic sampling. We will present measurements of several metamaterials designs.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

The authors experimentally demonstrate a resonant hybridization between the magnetic dipole structural resonance in the permeability of a fishnet metamaterial and an electric dipole material resonance in the permittivity of the dielectric spacer layer. The hybrid resonances in the permeability and the negative index response exhibit an anticrossing behavior. A simple analytic model and numerical simulations using a rigorous coupled-wave analysis are in excellent qualitative agreement with the experiment. © 2010 American Vacuum Society.

Abstract not provided.

Abstract not provided.