Plasmonic parametric resonance

This work is licensed under a Creative Commons Attribution 4.0 International License.We introduce the concept of plasmonic parametric resonance (PPR) as a novel way to amplify high angular momentum plasmonic modes of nanoparticles by means of a simple uniform optical pump. In analogy with parametric resonance in dynamical systems, PPR originates from the temporal modulation of one of the parameters governing the evolution of the state of the system. As opposed to conventional localized surface plasmon resonances (LSPR), we show that in principle any plasmonic mode of arbitrarily high order is accessible by PPR with a spatially uniform optical pump. Moreover, in contradistinction with other mechanisms of plasmonic amplification, the coherent nature of PPR lends itself to a more straightforward experimental detection approach. The threshold conditions for PPR are analytically derived. Schemes of experimental realization and detection are also discussed

Coupling of Optical Lumped Nanocircuit Elements and Effects of Substrates

We present here a model for the coupling among small nanoparticles excited by an optical electric field in the framework of our optical lumped nanocircuit theory [N. Engheta, A. Salandrino, and A. Alu Phys. Rev. Lett. 95, 095504 (2005)]. We derive how this coupling affects the corresponding nanocircuit model by adding controlled sources that depend on the optical voltages applied on the coupled particles. With the same technique, we can model also the presence of a substrate underneath nanocircuit elements, relating its presence to the coupling with a properly modeled image nanoparticle. These results are of importance in the understanding and the design of complex optical nanocircuits at infrared and optical frequencies.Comment: 21 pages, 4 figures, under revie

Parallel, Series, and Intermediate Interconnections of Optical Nanocircuit Elements Part 1: Analytical Solution

Following our recent development of the paradigm for extending the classic concepts of circuit elements to the infrared and optical frequencies [N. Engheta, A. Salandrino, A. Alu, Phys. Rev. Lett. 95, 095504 (2005)], in this paper we investigate the possibility of connecting nanoparticles in series and in parallel configurations, acting as nanocircuit elements, In particular, we analyze a pair of conjoined half-cylinders, whose relatively simple geometry may be studied and analyzed analytically. In this first part of the work, we derive a closed-form quasi-static analytical solution of the boundary-value problem associated with this geometry, which will be applied in Part II for a nanocircuit and physical interpretation of these results.Comment: 21 pages, 5 figure

Electromagnetic Propagation Anomalies In Waveguiding Structures And Scattering Systems

The effects related to diffraction and interference are ubiquitous in phenomena involving electromagnetic wave propagation, and are accurately predicted and described within the framework of classical electrodynamics. In the vast majority of the cases the qualitative features of the evolution of a propagating wave can be inferred even without detailed calculations. A field distribution will spread upon propagation, will accumulate phase along the direction of power flow, will exert mechanical forces upon scattering objects in the direction of propagation etc. When such predictions fail, counterintuitive effects and new functionalities can be engineered. In this work a series of exceptional cases under different degrees of field confinement have been isolated. In such instances the electromagnetic behavior significantly deviates from conventional cases. In particular, considering structures with monodimensional field confinement, the only possible class of diffraction free surface waves has been introduced. Again within the context of surface waves the mechanism of Enhanced Evanescent Tunneling (EET) has been proposed, which allows a net power flow to be sustained by evanescent fields only with applications to subdiffraction imaging. Increasing the degree of field confinement, a unique class of fully dielectric waveguide arrays able to support negative effective index modes has been theoretically demonstrated. Finally the opto-mechanical consequences of such effective negative index environments have been studied, highlighting counterintuitive properties. Instrumental to these findings was the introduction of a general theory of optical forces in terms of vector spherical harmonics

Far-field subdiffraction optical microscopy using metamaterial crystals: Theory and simulations

Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal’s output surface with a compressed angular spectrum, resulting in a magnified image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed

Far-field subdiffraction optical microscopy using metamaterial crystals: Theory and simulations

Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal’s output surface with a compressed angular spectrum, resulting in a “magnified” image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed

Negative index Clarricoats-Waldron waveguides for terahertz and far infrared applications

We explore a class of dielectrically loaded metallic waveguides capable of supporting negative index modes in the far infrared and terahertz regime. Principles of operation, modal structure and appropriate coupling schemes are analytically and numerically investigated. The extreme simplicity of the proposed design, along with the non-conventional and counter intuitive electromagnetic properties of this family of waveguides, makes these structures excellent candidates for the practical realization of negative index far infrared and terahertz devices with new and interesting functionalities. Generalizations and extensions of the suggested design are also discussed

Optical spectrometer at the nanoscale using optical Yagi-Uda nanoantennas

Here we present and analyze an optical spectrum analyzer at the nanometer scale that is able to distribute different frequency contents of the radiation of an optical dipole source into different directions in the space. The spectrum analyzer is composed of arrays of optical Yagi-Uda nanoantennas, forming relatively narrow radiation patterns operating at different frequencies. The optical Yagi-Uda nanoantennas composed of plasmonic core-shell nanoparticles are used as an example of building blocks for this idea in our study. Narrow radiation beams in such antenna arrays are realized by tailoring the scattering phase of the nanoparticles. The sensitivity of such an antenna array to the operating wavelength and the angular distribution of the radiation pattern, which is essential for the operation of the spectrum analyzer proposed here, is studied theoretically. The chromatic dispersion and the angular variation of the radiation pattern of such an optical spectrum analyzer are discussed in detail

Optical spectrometer at the nanoscale using optical Yagi-Uda nanoantennas

Here we present and analyze an optical spectrum analyzer at the nanometer scale that is able to distribute different frequency contents of the radiation of an optical dipole source into different directions in the space. The spectrum analyzer is composed of arrays of optical Yagi-Uda nanoantennas, forming relatively narrow radiation patterns operating at different frequencies. The optical Yagi-Uda nanoantennas composed of plasmonic core-shell nanoparticles are used as an example of building blocks for this idea in our study. Narrow radiation beams in such antenna arrays are realized by tailoring the scattering phase of the nanoparticles. The sensitivity of such an antenna array to the operating wavelength and the angular distribution of the radiation pattern, which is essential for the operation of the spectrum analyzer proposed here, is studied theoretically. The chromatic dispersion and the angular variation of the radiation pattern of such an optical spectrum analyzer are discussed in detail