Nicolae C. Panoiu

Bio: Nicolae C. Panoiu is an academic researcher from University College London. The author has contributed to research in topics: Silicon photonics & Plasmon. The author has an hindex of 43, co-authored 273 publications receiving 6977 citations. Previous affiliations of Nicolae C. Panoiu include University of New Mexico & London Centre for Nanotechnology.

Experimental Demonstration of Near-Infrared Negative-Index Metamaterials

Abstract: Metal-based negative refractive-index materials have been extensively studied in the microwave region. However, negative-index metamaterials have not been realized at near-IR or visible frequencies due to difficulties of fabrication and to the generally poor optical properties of metals at these wavelengths. In this Letter, we report the first fabrication and experimental verification of a transversely structured metal-dielectricmetal multilayer exhibiting a negative refractive index around 2 mu m. Both the amplitude and the phase of the transmission and reflection were measured experimentally, and are in good agreement with a rigorous coupled wave analysis.

Near-infrared double negative metamaterials

Abstract: We numerically demonstrate a metamaterial with both negative e and negative µ over an overlapping near-infrared wavelength range resulting in a low loss negative-index material. Parametric studies optimizing this negative index are presented. This structure can be easily fabricated with standard semiconductor processing techniques.

Engineering nonlinearities in nanoscale optical systems: physics and applications in dispersion-engineered silicon nanophotonic wires

Abstract: The nonlinear optics of Si photonic wires is discussed. The distinctive features of these waveguides are that they have extremely large third-order susceptibility χ(3) and dispersive properties. The strong dispersion and large third-order nonlinearity in Si photonic wires cause the linear and nonlinear optical physics in these guides to be intimately linked. By carefully choosing the waveguide dimensions, both linear and nonlinear optical properties of Si wires can be engineered. We review the fundamental optical physics and emerging applications for these Si wires. In many cases, the relatively low threshold powers for nonlinear optical effects in these wires make them potential candidates for functional on-chip nonlinear optical devices of just a few millimeters in length; conversely, the absence of nonlinear optical impairment is important for the use of Si wires in on-chip interconnects. In addition, the characteristic length scales of linear and nonlinear optical effects in Si wires are markedly different from those in commonly used optical guiding systems, such as optical fibers or photonic crystal fibers, and therefore guiding structures based on Si wires represent ideal optical media for investigating new and intriguing physical phenomena.

Nonlinear optical properties and applications of 2D materials: theoretical and experimental aspects

Abstract: In this review, we survey the recent advances in nonlinear optics and the applications of two-dimensional (2D) materials. We briefly cover the key developments pertaining to research in the nonlinear optics of graphene, the quintessential 2D material. Subsequently, we discuss the linear and nonlinear optical properties of several other 2D layered materials, including transition metal chalcogenides, black phosphorus, hexagonal boron nitride, perovskites, and topological insulators, as well as the recent progress in hybrid nanostructures containing 2D materials, such as composites with dyes, plasmonic particles, 2D crystals, and silicon integrated structures. Finally, we highlight a few representative current applications of 2D materials to photonic and optoelectronic devices.

Self-phase-modulation in submicron silicon-on-insulator photonic wires

Abstract: We measure the transmission of ps-pulses through silicon-on-insulator submicron waveguides for excitation wavelengths between 1400 and 1650 nm and peak powers covering four orders of magnitude. Self-phase-modulation induced spectral broadening is found to be significant at coupled peak powers of even a few tens of mW. The nonlinear-index coefficient, extracted from the experimental data, is estimated as n(2) ~ 5*10(-18) m(2)/W at 1500 nm. The experimental results show good agreement with model calculations that take into account nonlinear phase shift, first- and second order dispersion, mode confinement, frequency dispersion of n(2), and dynamics of two-photon-absorption-generated free carriers. Comparison with theory indicates that an observed twofold increase of spectral broadening between 1400 and 1650 nm can be assigned to the dispersion of n(2) as well as first order- rather than second-order dispersion effects. The analysis of pulse broadening, spectral shift and transmission saturation allows estimating a power threshold for nonlinearity-induced signal impairment in nanophotonic devices.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Perfect metamaterial absorber.

Abstract: We present the design for an absorbing metamaterial (MM) with near unity absorbance A(omega). Our structure consists of two MM resonators that couple separately to electric and magnetic fields so as to absorb all incident radiation within a single unit cell layer. We fabricate, characterize, and analyze a MM absorber with a slightly lower predicted A(omega) of 96%. Unlike conventional absorbers, our MM consists solely of metallic elements. The substrate can therefore be optimized for other parameters of interest. We experimentally demonstrate a peak A(omega) greater than 88% at 11.5 GHz.

Plasmonics for extreme light concentration and manipulation.

Abstract: The unprecedented ability of nanometallic (that is, plasmonic) structures to concentrate light into deep-subwavelength volumes has propelled their use in a vast array of nanophotonics technologies and research endeavours. Plasmonic light concentrators can elegantly interface diffraction-limited dielectric optical components with nanophotonic structures. Passive and active plasmonic devices provide new pathways to generate, guide, modulate and detect light with structures that are similar in size to state-of-the-art electronic devices. With the ability to produce highly confined optical fields, the conventional rules for light-matter interactions need to be re-examined, and researchers are venturing into new regimes of optical physics. In this review we will discuss the basic concepts behind plasmonics-enabled light concentration and manipulation, make an attempt to capture the wide range of activities and excitement in this area, and speculate on possible future directions.

Optical negative-index metamaterials

Abstract: Artificially engineered metamaterials are now demonstrating unprecedented electromagnetic properties that cannot be obtained with naturally occurring materials. In particular, they provide a route to creating materials that possess a negative refractive index and offer exciting new prospects for manipulating light. This review describes the recent progress made in creating nanostructured metamaterials with a negative index at optical wavelengths, and discusses some of the devices that could result from these new materials.

Infrared Perfect Absorber and Its Application As Plasmonic Sensor

Abstract: We experimentally demonstrate a perfect plasmonic absorber at λ = 1.6 μm. Its polarization-independent absorbance is 99% at normal incidence and remains very high over a wide angular range of incidence around ±80°. We introduce a novel concept to utilize this perfect absorber as plasmonic sensor for refractive index sensing. This sensing strategy offers great potential to maintain the performance of localized surface plasmon sensors even in nonlaboratory environments due to its simple and robust measurement scheme.