Alessandro Pianelli

Tampere University | UTA · Faculty of Engineering and Natural Sciences| Physics| Research Unit Photonics

A tunable graphene-based hyperbolic metamaterial is designed and numerically investigated in the mid-infrared frequencies. Theoretical analysis proves that by adjusting the chemical potential of graphene from 0.2 eV to 0.8 eV, the reflectance can be blue-shifted up to 2.3 μm. Furthermore, by modifying the number of graphene monolayers in the hyperb...

Confining near-infrared (NIR) and mid-infrared (MIR) radiation (1−10 μm) at the nanoscale is one of the main challenges in photonics. Thanks to the transparency of silicon in the NIR-MIR range, optoelectronic systems like electro-optical modulators have been broadly designed in this range. However, the trade-off between energy-per-bit consumption a...

Graphene-based hyperbolic metamaterials provide a unique scaffold for designing nanophotonic devices with active functionalities. In this work, we have theoretically demonstrated that the characteristics of a polarization-dependent tunable hyperbolic microcavity in the mid-infrared frequencies could be realized by modulating the thickness of the di...

Dielectric singularities (DSs) constitute one of the most exotic features occurring in the effective permittivity of artificial multilayers called hyperbolic metamaterials (HMMs). Associated to DSs, a rich phenomenology arises that justifies the ever-increasing interest profuse by the photonic community in achieving an active control of their prope...

All-optical ultrafast switches enabled by artificial materials are considered at the forefront of the next generation of photonic communications and data processing. During the last two decades, the photonic applications, impact, and interest have tremendously increased in the framework of epsilon-near-zero (ENZ) photonics. Here, we experimentally...

Refractory metal nitrides have recently gained attention in various fields of modern photonics due to their cheap and robust production technology, silicon-technology compatibility, high thermal and mechanical resistance, and competitive optical characteristics in comparison to typical plasmonic materials like gold and silver. In this work, we demo...

During the last two decades, the photonic applications, impact, and interest have tremendously increased. One of the most prominent optical phenomena in photonics is the so-called epsilon-near-zero (ENZ). This regime allows fast modulation of light. In this work, we experimentally propose a novel multilayered metamaterial that is Si-compatible, pos...

Dielectric Singularities (DSs) constitute one of the most exotic features occurring in the effective permittivity of artificial multilayers called Hyperbolic Metamaterials (HMMs). Associated to DSs, a rich phenomenology arises that justifies the ever-increasing interest profuse by the photonic community in achieving an active control of their prope...

Accurate determination of electronic transport properties of individual transparent conductive oxide layers, namely indium tin oxide (ITO), is essential for further development and design of photonic devices with ITO layer as a tunable ultrafast optoelectronic component. Precise magnetotransport measurements were here implemented to achieve carrier...

In this work we, propose a tunable 2D-hydrid epsilon-near-zero (ENZ) platform in telecom windows. Taking advantage to the intrinsically ENZ of the Indium-thin-oxide (ITO) and exploiting the graphene capability to dynamically tune the plasmon polaritons we were able to adjust the cross-over frequency, where the epsilon vanishes, in four telecom band...

We propose the study of subwavelength self-focusing solitons in hyperbolic metamaterials: nanoscale periodic structures consisting of alternating conductive and insulating layers. The self-focusing solitons supported by such media result from an interplay between tunneling of surface plasmon modes and nonlinear self-trapping. Therefore, dynamics in...

In this work, we theoretically study the quantum mechanisms that are an effective tool for analyzing the increase in the photonic density of states (PDOS) in relation to hyperbolic metamaterials (HMMs). Numerical results of the Purcell factor of HMM stack built on the basis of alternating layers of silica and silver are reported. We theoretically s...

In this work, we present a tunable multifunctional hyperbolic metamaterial composed of alternating layers of functionalized transparent conductive oxide (ITO) and insulating material (SiO2). Proposed plasmonic architecture allows to guide/squeeze and trapping the light at the nanoscale, which leads to a number of applications ranging from nanophoto...

Here we present the possibility to control the epsilon-near-zero (ENZ) region by properly designing a hyperbolic metamaterial (HMM) based on InAs, which allows for an adjustable absorption in mid-IR. Numerical results show that by increasing thickness of the undoped InAs layers we are from hyperbolic dispersion type I to ENZ and type II is observed...

A Type II hyperbolic metamaterial based on Al/HFO2 is designed and numerically investigated at in Near-IR telecommunication window. The numerical results show a blueshift in reflectance by adjusting the number of unit cells and the filling fraction. A characterization angle displays how the reflectance value changes as a function of the incidence a...

Here, we examine numerically the hyperbolic metamaterials based on graphene (1D-GHMM) in the mid-IR frequencies. Using the capability to tune the hyperbolic dispersion of graphene-based HMM by varying the chemical potential, we report a blueshift and tunability of the reflectance particularly for different incident angles in TM/TE modes. A type I,...

Here, we examine numerically the hyperbolic metamaterials based on graphene(1D-GHMM) in mid- IR frequencies. Using the ability to tune the hyperbolic dispersion of graphene-based HMM by varying the chemical potential, we report a tunable narrowband blueshift in reflectance, especially for different incidence angle in TE/TM modes. Furthermore, a typ...

In the intriguing field of active plasmonics, liquid crystals are considered a well-suited materials to be used as an active medium [1]. Recently, dual-frequency nematic liquid crystals (DFNLCs) pave the way for the so-called liquid-crystals plasmonics as a modulators since the material enables the tuning of plasmonic properties and behaves as an a...

In this work, we studied and analysed a particular variety of liquid crystals, the so-called dual-frequency nematic liquid crystals (DFNLCs). The interest was to perform dielectric spectroscopy and optical characterisation with two pure and doped mixtures of DFNLCs. By means the dielectric spectroscopy we observed a low value of crossover frequency...