A one-dimensional dielectric grating, based on a simple geometry, is proposed and investigated to enhance light absorption in a monolayer graphene exploiting guided mode resonances. Numerical findings reveal that the optimized configuration is able to absorb up to 60% of the impinging light at normal incidence for both TE and TM polarizations resulting in a theoretical enhancement factor of about 26 with respect to the monolayer graphene absorption (≈2.3%). Experimental results confirm this behavior showing CVD graphene absorbance peaks up to about 40% over narrow bands of a few nanometers. The simple and flexible design points to a way to realize innovative, scalable and easy-to-fabricate graphene-based optical absorbers.

We investigate graphene-based optical absorbers that exploit guided mode resonances (GMRs) attaining theoretically perfect absorption over a bandwidth of few nanometers (over the visible and near-infrared ranges) with a 40-fold increase of the monolayer graphene absorption. We analyze the influence of the geometrical parameters on the absorption rate and the angular response for oblique incidence. Finally, we experimentally verify the theoretical predictions in a one-dimensional, dielectric grating by placing it near either a metallic or a dielectric mirror, thus achieving very good agreement between numerical predictions and experimental results.

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.

In this paper, we propose a broadband silicon Mach-Zehnder switch (MZS) for wavelength division multiplexing applications on photonic networks on chip. The proposed reconfigurable switch is based on a single-stage three-waveguide interferometric configuration in which the phase shift is achieved via a p-i-n diode. The device is analyzed by the coupled-mode theory and by the finite-difference beam propagation method. The proposed configuration leads to a considerable increase in the bandwidth with respect to the conventional MZS. For example, the two-waveguide MZS with a gap g=0.30 μm between the two coupled waveguides exhibits bandwidth Δλ = 60 nm, crosstalk CT = - 15 dB, and insertion loss IL = 1.1 dB. Conversely, a bandwidth Δλ = 115 nm is achieved for the three-waveguide configuration to parity of the other parameters.

An optical multiplexer-demultiplexer based on an index-confined photonic band gap waveguide is proposed. The dropping of electromagnetic waves having a given frequency or a certain frequency band is obtained via a phase-shifted grating obtained by breaking the uniform period sequence to include a defect layer. The selective filtering properties of the proposed structure are simulated by means of a computer code relying on a bi-directional beam propagation method based on the method of lines.