All-optical majority gate based on an injection-locked laser.

An all-optical computer has remained an elusive concept. To construct a practical computing primitive equivalent to an electronic Boolean logic, one should utilize nonlinearity that overcomes weaknesses that plague many optical processing schemes. An advantageous nonlinearity provides a complete set of logic operations and allows cascaded operations without changes in wavelength or in signal encoding format.

High-bit rate ultra-compact light routing with mode-selective on-chip nanoantennas.

Optical nanoantennas provide a promising pathway toward advanced manipulation of light waves, such as directional scattering, polarization conversion, and fluorescence enhancement. Although these functionalities were mainly studied for nanoantennas in free space or on homogeneous substrates, their integration with optical waveguides offers an important "wired" connection to other functional optical components. Taking advantage of the nanoantenna's versatility and unrivaled compactness, their imprinting onto optical waveguides would enable a marked enhancement of design freedom and integration density for optical on-chip devices.

Simultaneous wavelength and orbital angular momentum demultiplexing using tunable MEMS-based Fabry-Perot filter.

In this paper, we experimentally demonstrate simultaneous wavelength and orbital angular momentum (OAM) multiplexing/demultiplexing of 10 Gbit/s data streams using a new on-chip micro-component-tunable MEMS-based Fabry-Perot filter integrated with a spiral phase plate. In the experiment, two wavelengths, each of them carrying two channels with zero and nonzero OAMs, form four independent information channels. In case of spacing between wavelength channels of 0.

Bidirectional UWB over fiber for WDM-PON system.

A novel bidirectional ultra-wideband over-fiber (UWBoF) system compatible with the wavelength-division-multiplexing (WDM) architecture is presented. In the proposed scheme, a 6th order Gaussian derivative is generated for UWB transmission in a downstream (DS) scenario, based on the directly modulated laser, accumulative chromatic dispersion in the transmission fiber and delay-line-interferometer (DLI). While the UWB signal is received from one of the DLI outputs, the other output is utilized to reuse the wavelength by injection locking a colorless Fabry-Perot laser diode (FP-LD).

Multipolar, time-dynamical model for the loss compensation and lasing of a spherical plasmonic nanoparticle spaser immersed in an active gain medium.

The plasmonic response of a metal nanoparticle in the presence of surrounding gain elements is studied, using a space and time-dependent model, which integrates a quantum formalism to describe the gain and a classical treatment for the metal. Our model fully takes into account the influence of the system geometry (nanosphere) and offers for the first time, the possibility to describe the temporal evolution of the fields and the coupling among the multipolar modes of the particle. We calculate the lasing threshold value for all multipoles of the spaser, and demonstrate that the dipolar one is lowest.

TDM-PON compatible generation of 10 Gbps NRZ and 1.25 Gbps UWB signals by a single light source.

A novel and cost-efficient technique is presented to generate non-return-to-zero (NRZ) and ultra-wideband (UWB) signals in different time slots of time division multiplexing-passive optical network (TDM-PON) by using a single chirped controlled semiconductor laser associated with an optical bandpass filter. In this technique, the chirp of the laser is controlled by different bias burst amplitudes (BBA) for different time slots. Through the proper selection of the burst amplitudes, 10 Gbps NRZ and 1.

Wavelength-selective orbital-angular-momentum beam generation using MEMS tunable Fabry-Perot filter.

We demonstrate an on-chip device capable of wavelength-selective generation of vortex beams, which is realized by a spiral phase plate integrated onto a microelectromechanical system (MEMS) tunable filter. This vortex MEMS filter, being capable of functioning simultaneously in both wavelength and orbital-angular-momentum (OAM) domains at the 1550 nm wavelength regime, is considered as a compact, robust, and cost-effective solution for simultaneous OAM- and wavelength-division multiplexed optical communications. The experimental OAM spectra for azimuthal orders 1, 2, and 3 show an OAM state purity >92% across a wavelength range of more than 30 nm.

Toroidal qubits: naturally-decoupled quiet artificial atoms.

The requirements of quantum computations impose high demands on the level of qubit protection from perturbations; in particular, from those produced by the environment. Here we propose a superconducting flux qubit design that is naturally protected from ambient noise. This decoupling is due to the qubit interacting with the electromagnetic field only through its toroidal moment, which provides an unusual qubit-field interaction, which is suppressed at low frequencies.

Nonradiating anapole modes in dielectric nanoparticles.

Nonradiating current configurations attract attention of physicists for many years as possible models of stable atoms. One intriguing example of such a nonradiating source is known as 'anapole'. An anapole mode can be viewed as a composition of electric and toroidal dipole moments, resulting in destructive interference of the radiation fields due to similarity of their far-field scattering patterns.

Data transmission in long-range dielectric-loaded surface plasmon polariton waveguides.

We demonstrate the data transmission of 10 Gbit/s on-off keying modulated 1550 nm signal through a long-range dielectric-loaded surface plasmon polariton waveguide structure with negligible signal degradation. In the experiment the bit error rate penalties do not exceed 0.6 dB over the 15 nm wavelength range and received optical power between -7 and 3 dBm.

Modeling of transient dynamics in two-dimensional circular microresonators using the pulsed complex source point beam concept.

An analytical method for transient dynamics description in microresonators is used to characterize and visualize the transient effects. In the frame of this method, the pulsed complex source point concept is used to simulate an incident transient beam. The excited fields in the microcavity are described by means of a rigorous mathematical approach that is based on the analytical solution in the Laplace transform domain and accurate evaluation of residues at singular points corresponding to the excited modes.

THz bandwidth optical switching with carbon nanotube metamaterial.

We provide the first demonstration of exceptional light-with-light optical switching performance of a carbon nanotube metamaterial - a hybrid nanostructure of a plasmonic metamaterial with semiconducting single-walled carbon nanotubes. A modulation depth of 10% in the near-IR with sub-500 fs response time is achieved with a pump fluence of just 10 μJ/cm², which is an order of magnitude lower than in previously reported artificial nanostructures. The improved switching characteristics of the carbon nanotube metamaterial are defined by an excitonic nonlinearity of carbon nanotubes resonantly enhanced by a concentration of local fields in the metamaterial.

Genuine effectively biaxial left-handed metamaterials due to extreme coupling.

Most left-handed metamaterials cannot be described by local effective permittivity or permeability tensors in the visible or near-infrared due to the mesoscopic size of the respective unit cells and the related strong spatial dispersion. We lift this problem and propose a metamaterial exhibiting artificial magnetism that does not suffer from this restriction. The artificial magnetism arises from the extreme coupling between both metallic films forming the unit cell.

Optical properties of metamaterials based on asymmetric double-wire structures.

We performed theoretical and experimental investigations of the magnetic properties of metamaterials based on asymmetric double-wire structures. Using the multipole model for the description of metamaterials, we investigated the influence of the geometrical asymmetry of the structure on the macroscopic effective parameters. The results show that the larger wire in the system dominates the dynamics of the structure and defines the orientation and the strength of the microscopic currents.

Thermal nonlinear effects in hybrid silica/polymer microdisks.

The linear and thermal nonlinear spectral responses of silica and hybrid silica/polymer microdisk resonators are investigated. Both types of resonators can be fabricated using the same technological procedure with only slight modification. An extra polymer layer results in opposite sign of the nonlinear thermal optical response of the hybrid microdisks compared to the pure silica ones, which can be explained by the different thermorefractive coefficients of silica and polymer.

Understanding the electric and magnetic response of isolated metaatoms by means of a multipolar field decomposition.

We introduce a technique to decompose the scattered near field of two-dimensional arbitrary metaatoms into its multipole contributions. To this end we expand the scattered field upon plane wave illumination into cylindrical harmonics as known from Mie's theory. By relating these cylindrical harmonics to the field radiated by Cartesian multipoles, the contribution of the lowest order electric and magnetic multipoles can be identified.

Double-element metamaterial with negative index at near-infrared wavelengths.

We present the realization of a metamaterial that combines double cut wires and continuous wires in its unit cell. This double-element geometry together with the applied layer-by-layer fabrication technique permits an independent tuning of the geometry of the unit-cell components. The characterization of the samples is based on the measurement of transmission and reflection spectra combined with rigorous numerical simulations.

Polarization-independent negative-index metamaterial in the near infrared.

We present and evaluate theoretically and experimentally a design for a negative-index metamaterial that is termed the "Swiss cross" structure. Compared with the established fishnet structure, the proposed design eliminates the drawback of polarization-dependent effective optical parameters. The new design is fabricated by means of e-beam technology and experimentally analyzed using spectroscopic techniques.

Nonlinear thermal effects in optical microspheres at different wavelength sweeping speeds.

Results of detailed experimental investigations of the power and sweeping speed dependent resonance bandwidth and resonance wavelength shift in microsphere resonators are presented. The experimental manifestations of the nonlinear effects for the different sweeping modes are considered and a possibility of separation between the Kerr and thermal nonlinearities is discussed. As it follows from the detailed comparison between theory and experiments, a single mode theoretical model, based on the mean field approximation, gives a satisfactory description of the experimental data only at small coupling powers and fast sweeping.

The origin of magnetic polarizability in metamaterials at optical frequencies - an electrodynamic approach.

We explain the origin of the electric and particular the magnetic polarizabiltiy of metamaterials employing a fully electromagnetic plasmonic picture. As example we study an U-shaped split-ring resonator based metamaterial at optical frequencies. The relevance of the split-ring resonator orientation relative to the illuminating field for obtaining a strong magnetic response is outlined.