The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Photonic crystal fibers are a new class of optical fibers. Their artificial crystal-like microstructure results in a number of unusual properties. They can guide light not only through a well-known total internal reflection mechanism but using also photonic bandgap effect. In this paper different properties possible to obtain in photonic crystal fibers are reviewed. Fabrication and modeling methods are also discussed.

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Photonic Crystal Fibers

In the course of the past several years, a new level of understanding has been achieved about conditions for the existence, stability, and generation of spatiotemporal optical solitons, which are nondiffracting and nondispersing wavepackets propagating in nonlinear optical media. Experimentally, effectively two-dimensional (2D) spatiotemporal solitons that overcome diffraction in one transverse spatial dimension have been created in quadratic nonlinear media. With regard to the theory, fundamentally new features of light pulses that self-trap in one or two transverse spatial dimensions and do not spread out in time, when propagating in various optical media, were thoroughly investigated in models with various nonlinearities. Stable vorticity-carrying spatiotemporal solitons have been predicted too, in media with competing nonlinearities (quadratic–cubic or cubic–quintic). This article offers an up-to-date survey of experimental and theoretical results in this field. Both achievements and outstanding difficulties are reviewed, and open problems are highlighted. Also briefly described are recent predictions for stable 2D and 3D solitons in Bose–Einstein condensates supported by full or low-dimensional optical lattices.

https://iopscience.iop.org/article/10.1088/1464-4266/7/5/R02/pdf

Spatiotemporal optical solitons

We provide a self-consistent electromagnetic theory of the coupling between dipole emitters and dissipative nanoresonators. The theory that relies on the concept of quasinormal modes with complex frequencies provides an accurate closed-form expression for the electromagnetic local density of states of any photonic or plasmonic resonator with strong radiation leakage, absorption, and material dispersion. It represents a powerful tool to calculate and conceptualize the electromagnetic response of systems that are governed by a small number of resonance modes. We use the formalism to revisit Purcell's factor. The new formula substantially differs from the usual one; in particular, it predicts that a spectral detuning between the emitter and the resonance does not necessarily result in a Lorentzian response in the presence of dissipation. Comparisons with fully vectorial numerical calculations for plasmonic nanoresonators made of gold nanorods evidence the high accuracy of the predictions achieved by our semianalytical treatment.

https://hal-iogs.archives-ouvertes.fr/hal-00850459/document

Theory of the spontaneous optical emission of nanosize photonic and plasmon resonators.

We demonstrate the exceptionally-high third-order nonlinearity of integrated mono-layer graphene-silicon hybrid optoelectronics, enabling ultralow power resonant optical bistability, self-induced regenerative oscillations, and coherent four-wave mixing, all at few femto-joule cavity recirculating energies.

http://www.columbia.edu/cu/nanohv/papers/grapheneFWM_regenerationOscillations_GuWong_naturePhotonics2012.pdf

Regenerative oscillation and four-wave mixing in graphene optoelectronics

A 3D full-vectorial Beam Propagation Method is successfully applied to compute both the propagation constants and the modal profiles in high-contrast silica-air index-guiding Photonic Crystal Fibers. The approach is intrinsically suited to investigate longitudinally varying structures or propagation and polarization effects, which are of practical interest for advanced optical applications. As an example we model a dual-core coupler, showing that efficient polarization preserving coupling can be expected.

Full vectorial BPM modeling of Index-Guiding Photonic Crystal Fibers and Couplers

Some important properties of photonic wire Bragg grating structures have been investigate. The design, obtained as a generalisation of the full-width gap grating, has been modelled using 3D finite-difference time-domain simulations. Different types of stop-band have been observed. The impact of the grating geometry on the lowerst order (longest wavelength) stop-band has been investigated - and has identified deeply indented confirugations where reduction of the stop-bandwidth and of the reflectivity occurred. Our computational results have been substantially validated by an experimental demonstration of the fundamental stop-band of photonic wire Bragg gratings fabricated on silicon-on-insulator material. The accuracy of two distinct 2D computational models based on the effective index method has also been studied - because of their inherently much greater rapidity and consequent utility for approximate initial designs. A 2D plan-view model has been found to reproduce a large part of the essential features of the spectral response of full 3D models.

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Modelling of photonic wire bragg gratings

We show that a semiconductor nanocavity where the dominant nonlinear mechanism is the refractive index change induced by carriers generated through two-photon absorption can become unstable, exhibiting the onset of spontaneous oscillations (self-pulsing). The linear stability analysis, validated through numerical integration of a mean-field model, leads us to predict oscillations to take place typically in the 10-ps range at input power levels of the order of 15 mW.

Self-pulsing driven by two-photon absorption in semiconductor nanocavities

In this paper we propose a novel hybrid optical plasmonic Vivaldi antenna for operation in the standard C telecommunication band for wavelengths in the 1550 nm range. The antenna is fed by a silicon waveguide and is designed to have high gain and large bandwidth. The shape of the radiation pattern, with a main lobe along the antenna axis, makes this antenna suitable for point-to-point connections for inter- or intra-chip optical communications. Direct port-to-port short links for different connection distances and in a homogeneous environment have also been simulated to verify, by comparing the results of a full-wave simulation with the Friis transmission equation, the correctness of the antenna parameters obtained via near-to-far field transformation.

Integrated Vivaldi plasmonic antenna for wireless on-chip optical communications.

We predict that the combination of space and time modulational instabilities that occur by means of parametric wave mixing in quadratic media leads to colored conical emission This phenomenon should be observed under conditions usually employed in second-harmonic experiments

Gaetano Bellanca

Papers

Full vectorial BPM modeling of Index-Guiding Photonic Crystal Fibers and Couplers

Modelling of photonic wire bragg gratings

Self-pulsing driven by two-photon absorption in semiconductor nanocavities

Integrated Vivaldi plasmonic antenna for wireless on-chip optical communications.

Colored conical emission by means of second-harmonic generation.