The fundamental electric dipolar resonance of metallic nanostrips placed on top of a dielectric waveguide can be excited via evanescent wave coupling, thus giving rise to broad dips in the transmission spectrum of the waveguide. Here we show via numerical simulations that narrower and steeper Fano-like resonances can be obtained by asymmetrically coupling in the near field a larger nanostrip—supporting an electric quadrupole in the frequency regime of interest—to the original, shorter nanostrip. Under certain conditions, the spectral response corresponding to the electromagnetically induced transparency phenomenon is observed. We suggest that this hybrid plasmonic–photonic approach could be especially relevant for sensing or all-optical switching applications in a photonic integrated platform such as silicon photonics.

The dynamic performance of a packaged photonic network-on-chip (NoC) based on multi-microrings is experimentally demonstrated. Controlled by a scheduler implemented in an FPGA, the packaged photonic NoC exhibits a BER penalty of approximately 0.5 dB.

This paper aims to present the design and the achieved results on a CMOS electronic and photonic integrated device for low cost, low power, transparent, mass-manufacturable optical switching. An unprecedented number of integrated photonic components (more than 1000), each individually electronically controlled, allows for the realization of a transponder aggregator device which interconnects up to eight transponders to a four direction colorless-directionless-contentionless ROADM. Each direction supports 12 200-GHz spaced wavelengths, which can be independently added or dropped from the network. An electronic ASIC, 3-D integrated on top of the photonic chip, controls the switch fabrics to allow a complete and microsecond fast reconfigurability.

A multi microring network on chip with 6 ports has been fabricated in SOI, packaged and characterized. The BER penalty for two simultaneous 10Gb/s transmissions of up to 5 hops is below 1 dB at a BER of 10(exp -9).

This paper demonstrates different bidirectional transmissions in a packaged ring-based optical network-on-chip (NoC) with 12 add-drop microrings. Shared-source and shared-destination microring configurations have been tested for paths of different lengths, showing a maximum penalty of 1 dB and 2 dB at 10 -9 BER, respectively.

We propose a very compact dual-band quarter-wave plate (QWP) which is inspired on extraordinary transmission subwavelength hole arrays. To control independently orthogonal polarizations, the original square holes are connected with vertical slits and meander lines replace their lateral straight sides. The structure is numerically analyzed and experimentally demonstrated at terahertz frequencies. The metasurface exhibits an experimental fractional bandwidth equal to 16.8% and 2.9% (52.1% and 4.3% in simulation) at 1 THz and 2.2 THz in a structure as compact as 0.13? and 0.29λ, respectively.

In this work, we present a metamaterial working at terahertz frequencies made over a flexible polypropylene substrate. The experimental measurements, in accordance with the numerical calculations, show the metamaterial reliance on the impinging electric field polarization. The structure’s symmetry yields purely electrical resonant responses eliminating bianisotropy effects. The widely used bendable polypropylene polymer may promote the insertion of metamaterial-based structures with special electromagnetic response in a number of objects of our daily lives such as textiles, automotive components, and sensing.

We present a method that enables the implementation of full three-dimensional (3D) transformation media with minimized anisotropy. It is based on a special kind of shape-preserving mapping and a subsequent optimization process. For sufficiently smooth transformations, the resulting anisotropy can be neglected, paving the way for practically realizable 3D devices. The method is independent of the considered wave phenomenon and can thus be applied to any field for which a transformational technique exists, such as acoustics or thermodynamics. Full 3D isotropy has an additional important implication for optical transformation media, as it eliminates the need for magnetic materials in many situations. To illustrate the potential of the method, we design 3D counterparts of transformation-based electromagnetic squeezers and bends.

We present a mid-infrared inductor that when applied to an extraordinary transmission hole array produces a strong redshift of the resonant peak accompanied by an unprecedented enlargement of the operation bandwidth. The importance of the result is twofold: from a fundamental viewpoint, the direct applicability of equivalent circuit concepts borrowed from microwaves is demonstrated, in frequencies as high as 17 THz upholding unification of plasmonics and microwave concepts and allowing for a simplification of structure design and analysis; in practical terms, a broadband funnelling of infrared radiation with fractional bandwidth and efficiency as high as 97% and 48%, respectively, is achieved through an area less than one hundredth the squared wavelength, which leads to an impressive accessible strong field localization that may be of great interest in sensing applications.

Expanding ideas from microwaves, we demonstrate experimentally a terahertz inductor by using meander-lines in a canonical extraordinary transmission (ET) hole array leading to a strong resonance's redshift and an unprecedented enlargement of the operation bandwidth.

A dual-band quarter-wave plate based on a modified extraordinary transmission hole array is numerically analyzed and experimentally demonstrated at terahertz frequencies. To control independently orthogonal polarizations, the original square holes are connected with vertical slits and their lateral straight sides are replaced by meander lines. This smart design enables dual-band operation with unprecedented fractional bandwidths in a compact structure. Considering a flattening deviation lower than 40% of the optimum value, a fractional bandwidth of 53.8% and 3.8% is theoretically obtained (16.8% and 2.9% in the experiment) at 1 and 2.2 THz, respectively. At these two frequencies, the structure is 0.13-λ and 0.29-λ thick, respectively. Given the compactness of the whole structure and the performance obtained, this quarter-wave plate is presented as a competitive device for the terahertz band.

We propose a very compact metasurface that works as a quarter-wave plate at two different frequencies, 1 THz and 2.2 THz. The fractional bandwidth of the first band is remarkably 32.2%, beyond the state-of-the-art.

Light-matter interaction at optical frequencies is mostly mediated by the electric component of the electromagnetic field, with the magnetic component usually being considered negligible. Recently, it has been shown that properly engineered metallic nanostructures can provide a magnetic response at optical frequencies originated from real or virtual flows of electric current in the structure. In this work, we demonstrate a magnetic plasmonic mode which emerges in closely spaced thick gold nanorings. The plasmonic resonance obtains a magnetic dipole character by sufficiently increasing the height of the nanorings. Numerical simulations show that a virtual current loop appears at resonance for sufficiently thick nanorings, resulting in a strong concentration of the magnetic field in the gap region (magnetic hot spot). We find that there is an optimum thickness that provides the maximum magnetic intensity enhancement (over 200-fold enhancement) and give an explanation of this observation. This strong magnetic resonance, observed both experimentally and theoretically, can be used to build new metamaterials and resonant loop nanoantennas at optical frequencies.

In this work, we tune the frequency of the resonant peak associated to extraordinary transmission phenomenon by changing slightly the topology of typical subwavelength square apertures. By substituting the vertical lateral walls for meander-lines it is possible to move the extraordinary transmission peak downward accompanied by an unprecedented enlargement of the fractional bandwidth. This phenomenon is theoretically analyzed from an equivalent circuit perspective and demonstrated experimentally at the millimeter-wave and mid-infrared band. A wide range of applications may benefit from this, since now the extraordinary transmission happens far away from the onset of higher order diffracted modes.

We study the electromagnetic behavior of a structure consisting of coupled aluminum nanodisks on a silicon waveguide at telecom wavelengths. Numerical simulations show that the fundamental TE-like waveguide mode excites a localized magnetic plasmon resonance between adjacent nanodisks with suitable dimensions, leading to transmission dips. For a sufficient number of disks (periodically distributed along the propagation direction), the structure supports a magnetic mode arising from a magneto-inductive coupling between neighboring nanodisks, as revealed by an Eigenmode analysis. The transmission response of the samples was measured for both polarizations through an end-fire set-up, confirming that the strong resonances are only present for TE polarization. Measurements and simulations are in good agreement, showing that the resonances strength is maximized for three coupled nanodisks.

Optical measurements of the transmission spectra through nanofabricated planar arrays of silver u-shaped nanowires on a silicon substrate resonating at infrared frequencies are performed. Good agreement with the numerically simulated surface plasmon standing wave resonances supported by the structures is found. Such resonances exhibit field enhancement and are able to provide magnetic and electric responses when used as the unit cell of a metamaterial. The magnetic excitation of the resonators using oblique incidence is shown to be drastically reduced by the existence of a high index substrate such as silicon.

In this work, we show that closely-spaced gold nanohoops periodically distributed in a square lattice can provide a strong magnetic response in the near infrared regime when illuminated under normal incidence (perpendicular to the structure plane). Therefore, just a single metallic layer is needed to achieve the magnetic activity. A key point to achieve this response is that the aspect ratio must be higher than 1. Transmission and reflection spectra taken by means of a Fourier-Transform Infrared spectrometer show a strong absorbance peak at a wavelength that can be tuned by modifying the hole radius of the nanohoops or the underlying dielectric substrate. Numerical simulations show that at the resonance wavelength a virtual current loop is created, giving rise to a strong magnetic moment and a large magnetic field enhancement in the space between nanohoops.

We present a way of exciting surface plasmon polaritons along non-patterned metallic surfaces by means of a flat squeezing slab designed with transformation optics. The slab changes the dispersion relation of incident light, enabling evanescent coupling to propagating surface plasmons. Unlike prism couplers, the proposed device does not introduce reflections at its input interface. Moreover, its compact geometry is suitable for integration. A feasible dielectric implementation of the coupler is suggested. Finally, we show that the angular response of the device can be engineered by using a non-uniform compression factor. As an example, we design a coupler with a half-power angular bandwidth 2.5 times higher than that of a conventional dielectric coupler.

We have studied the relationship between internal-surface plasmon polaritons and negative permeability in cascaded patterned metallic layers. By properly selecting the dielectric thicknesses of the multilayer structure, the negative effective index can broaden which could be of potential use in the design of metamaterials. The excitations of cladding modes are also shown to cause extraordinary light transmission. Several subwavelength hole arrays are fabricated and characterized showing extraordinary light transmission peaks. With the presented results we hope to extend the potential of these structures for use in modern developing applications.