Mikhail Vasilevskiy

A primer on surface plasmon-polaritons in graphene

We discuss the properties of surface plasmons-polaritons in graphene and describe four possible ways of coupling electromagnetic radiation in the terahertz (THz) spectral range to this type of surface waves: (i) the attenuated total reflection (ATR) method using a prism in the Otto configuration, (ii) graphene micro-ribbon arrays or monolayers with modulated conductivity, (iii) a metal stripe on top of the graphene layer, and (iv) graphene-based gratings. The text provides a number of original results along with their detailed derivation and discussion.

Competition between ferroelectric and semiconductor properties in Pb(Zr0.65Ti0.35)O3 thin films deposited by sol–gel

Asymmetric metal–ferroelectric–metal (MFM) structures were manufactured by sol–gel deposition of a lead zirconate-titanate (PZT with Zr/Ti ratio 65/35) film on Pt-coated Si, with a Au top electrode. The average remnant polarization of 9 μC/cm2 and the coercive field of 39 kV/cm were obtained from the hysteresis loop measurements. A detailed analysis of the polarization–electric field (P–E), capacitance–voltage (C–V), and current–voltage (I–V) measurement results allowed us to estimate the near-electrode space-charge region thickness (roughly half of the film thickness at zero voltage), net doping concentration (around 1018 cm−3), built-in potential (in the 0.4–0.8 V range, depending on the injecting electrode), and dynamic dielectric constant (5.2). The current logarithm–voltage dependence for the field-enhanced Schottky emission obeys a “1/4” law. The spectral distribution of the short circuit current measured under continuous light illumination in the 290–800 nm range exhibits a cutoff wavelength at 370...

Mechanism for graphene-based optoelectronic switches by tuning surface plasmon-polaritons in monolayer graphene

It is shown that one can explore the optical conductivity of graphene, together with the ability of controlling its electronic density by an applied gate voltage, in order to achieve resonant coupling between an external electromagnetic radiation and surface plasmon-polaritons in the graphene layer. This opens the possibility of electrical control of the intensity of light reflected inside a prism placed on top of the graphene layer, by switching between the regimes of total reflection and total absorption. The predicted effect can be used to build graphene-based optoelectronic switches.

Tuning of the surface plasmon resonance in TiO2/Au thin films grown by magnetron sputtering: The effect of thermal annealing

Nanocomposites consisting of a dielectric matrix, such as TiO2, with embedded noble metal nanoparticles (NPs) possess specific optical properties due to the surface plasmon resonance (SPR) effect, interesting for several applications. The aim of this work is to demonstrate that these properties are sensitive to the nanostructure of magnetron-sputtered TiO2/Au thin films, which can be tuned by annealing. We study the role of the shape and size distribution of the NPs, as well as the influence of the crystallinity and phase composition of the host matrix on the optical response of the films. All these characteristics can be modified by vacuum annealing treatments of the deposited films. A theoretical interpretation and modeling of the experimental results obtained is presented. The model involves a modified Maxwell-Garnett approach for the effective dielectric function of the composite (describing the SPR effect) and the transfer matrix formalism for multilayer optics. Input data are based on the experiment...

Optical bistability of graphene in the terahertz range

We are grateful to D. K. Ferry and A. A. Ignatov for sharing their insights on the early developments of Boltzmann transport theory for semiconductors, and we thank N. A. Mortensen for useful remarks. This work was partially supported by the FEDER COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) through Grant No. PEst-C/FIS/UI0607/2013. We acknowledge support from the EC under Graphene Flagship (Contract No. CNECT-ICT-604391). The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Research Foundation, Project No. DNRF58. The work contract of J.E.S. is financed within the framework of the Program of Recruitment of Post Doctoral Researchers for the Portuguese Scientific and Technological System, with the Operational Program Human Potential (POPH) of the QREN, participated in by the European Social Fund (ESF) and national funds of the Portuguese Ministry of Education and Science (MEC).

Tunable graphene-based polarizer

It is shown that an attenuated total reflection structure containing a graphene layer can operate as a tunable polarizer of the electromagnetic radiation. The polarization angle is controlled by adjusting the voltage applied to graphene via external gate. The mechanism is based on the resonant coupling of

Graphene-based polaritonic crystal

p-

Unusual reflection of electromagnetic radiation from a stack of graphene layers at oblique incidence

polarized electromagnetic waves to the surface plasmon-polaritons in graphene. The presented calculations show that, at resonance, the reflected wave is almost 100%

Exact solution for square-wave grating covered with graphene: surface plasmon-polaritons in the terahertz range

s-

FIR absorption in CdSe quantum dot ensembles

polarized.