Alexander M. Dubrovkin

Graphene-based tunable plasmonic Bragg reflector with a broad bandwidth

We propose and numerically analyze a plasmonic Bragg reflector formed in a graphene waveguide. The results show that the graphene plasmonic Bragg reflector can produce a broadband stopband that can be tuned over a wide wavelength range by a small change in the Fermi energy level of graphene. By introducing a defect into the Bragg reflector, we can achieve a Fabry-Perot-like microcavity with a quality factor of 50 for the defect resonance mode formed in the stopband. The proposed Bragg reflector could be used as a broadband ultrafast tunable integrated filter and a broadband modulator. In addition, the defect microcavity may find applications in graphene-based resonators.

Monolayers of WxMo1−xS2 alloy heterostructure with in-plane composition variations

We report the fabrication of single-crystal monolayer WxMo1−xS2 alloy triangles using chemical vapor deposition method. Raman and photoluminescence property are investigated in correlation to the composition. In the monolayer triangles, the photoluminescence peak shifts continuously from 687.4 nm at the triangle center to 633.6 nm at the edge, corresponding to a switch from MoS2 to WS2 across the heterojunction. This composition-graded alloy may have interesting functions in broadband photodetection and multi-color light emission.

The reduction of surface plasmon losses in quasi-suspended graphene

Highly confined surface plasmons on graphene attract substantial interest as potential information carriers for highly integrated photonic data processing circuits. However, plasmon losses remain the main obstacle for implementation of such devices. In near-field microscopic experiments performed at the wavelength of 10 μm we show that a substantial reduction of plasmon damping can be achieved by placing a nanometric polymer nano-dots spacer between the graphene layer and the supporting silicon oxide slab making graphene quasi-suspended. We argue that reduction of plasmon losses is attributed to weaker coupling with substrate phonons in the quasi-suspended graphene.

Visible range plasmons in topological insulators

Near-field imaging in the visible reveals the existence of localized and propagating plasmons on the surface of topological insulator. We also report ab-initio band structure calculations explain the origin of plasmonic response in chalcogenide compounds.

Dataset for Ultra-confined surface phonon polaritons in molecular layers of van der Waals dielectrics

Dataset supporting: Dubrovkin, Alexander et al. (2018) Ultra-confined surface phonon polaritons in molecular layers of van der Waals dielectrics. Nature Communications

Ultra confined polaritons in atomically layered dielectrics

We report the first observation of highly confined polaritons with wavelength two orders of magnitude shorter than the free space wavelength that propagates on the surface of silicon carbide crystals covered by a few atomic layers of molybdenum disulfide.

Dataset for Visible Range Plasmonic Modes on Topological Insulator Nanostructures

Dataset supporting: Dubrovkin, Alexander et al (2016) Visible range plasmonic modes on topological insulator nanostructures. Advanced Optical Materials.