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Graphene is a material with exceptional optical, electrical and physicochemical properties that can be combined with dielectric waveguides. To date, several optical devices based on graphene have been modeled and fabricated operating in the near-infrared range and showing excellent performance and broad application prospects. This paper covers the main aspects of the optical behaviour of graphene and its exploitation as electrodes in several device configurations. The work compares the reported optical devices focusing on the wavelength tuning, showing how it can vary from a few hundred up to a few thousand picometers in the wavelength range of interest. This work could help and lead the design of tunable optical devices with integrated graphene layers that operate in the NIR. [ABSTRACT FROM AUTHOR]

In this paper, a novel doubly resonant three-dimensional (3D) nanodisk Yagi-Uda antenna, conceived for realizing wireless optical links within electronic circuits, is proposed. The prominent emitting properties of this nanoantenna have been deeply investigated both in the near and far field through a useful comparison with a more traditional 3D nanorod Yagi-Uda antenna. The behavior of the nanodisk antenna, both configured as a single nanoantenna and arranged in planar arrays, have been illustrated, emphasizing its improved performances with relation to crucial aspects as directional features, wavelength bands of operation, frequency tuning, and polarization influence on radiation. In particular, the single nanodisk antenna has been accurately designed to enhance the transmission feature in the near field at the wavelengths λ = 1.3 and λ = 1.55 μm. Also, the emission pattern of the array of nanodisk antennas has been properly tailored to ensure high peaks of directivity and narrow beam width in those ranges. Hence, efficient unidirectional angle patterns have been shaped for any operation wavelength and dimensions of the array, reaching extremely effective outcomes for a 3 × 3 array, which exhibits a maximum of directivity of 19 and 17.6 and −3 dB points at 18° and 21° for λ = 1.3 and λ = 1.55 μm, respectively. [ABSTRACT FROM AUTHOR]

We analyze the effective opening of finite bands of inhibited transmission in realistic systems excited by actual out-of-plane sources. We first observe how the excitation of surface plasmon polaritons in one-dimensional arrays of metal slits depends on the angle of incidence of the source field. Then, the well-known grating-coupling equation is revised in order to find an asymmetric structure with equivalent parameters which, under perfectly normal excitation, is able to exhibit surface plasmon polariton modes at the same wavelengths of the original structure which undergoes a nonorthogonal incidence of the light. In this way we demonstrate through finite-element simulations that a realistic system, probed by a source beam in a finite light-cone, can be effectively decomposed in several equivalent systems with different physical and geometrical parameters, with results in the enlargement of the theoretically expected punctual minimum of transmission. [ABSTRACT FROM AUTHOR]

In this paper, a novel plasmonic bandgap cavity inducing the enhancement of extraordinary optical transmission is presented. Numerical simulations have been performed to model a free-standing structure made of a one-dimensional periodic arrangement of gold strips. Two different values of the lattice constant have been properly chosen to realize a double heterostructure-like cavity to accomplish extraordinary optical transmission assisted by the formation of a plasmonic bandgap in the adjacent regions. Numerical results prove the capability of this optical device to efficiently transmit input light beams with far-field transmission values close to 100% due to the excitation of surface plasmon polariton resonant modes. [ABSTRACT FROM AUTHOR]

An active optical switch based on the InGaAsP/InP photonic bandgap (PBG) buried waveguide is proposed. The device, which is made of a periodic grating patterned on a buried waveguide, exploits the localization of states in the PBG induced by the presence of an active defect. The wavelength of the localized state can be shifted by properly choosing the defect length and the injected current density in order to achieve a wavelength-selective switching behavior. Proprietary codes based on the bidirectional beam propagation method and the method of lines (BBPM-MoL) were used for the simulations of the optical device taking into account the rate equations to model the interaction between the optical signal and the active medium. Design curves are provided and parameterized to give general design rules. From the numerical analysis, the proposed device exhibits good theoretical performances in terms of crosstalk (CT<-20~dB), modulation depth (MD>0.9), response time (in the subnanosecond range), and maximum size (<170~\mum). [ABSTRACT FROM PUBLISHER]