arXiv subjects

David Karakhanyan

Publications and source records attributed to David Karakhanyan.

6 recordsLinked to original sources

arXiv2026

Probing the temperature dependence of dielectric function of ternary transition metal dichalcogenides: towards thermo-driven ultrathin photonic components

Transition metal dichalcogenides (TMDs), along with their ternary derivatives, have attracted considerable attention mostly due to pronounced excitonic resonances emerging in visible (Vis) and near-infrared (NIR) spectral regions, enabling strong light-matter interaction. Nevertheless, a comprehensive insight of the temperature-dependent optical dispersions for the most of representatives of the family remains yet unrevealed. Here, we report on systematic studies of dielectric permittivity functions of uniaxial ternary MoSSe and WSSe across 430-1000 nm spectral region over a broad temperature window of 80-670 K. We show that the temperature evolution of their dielectric responses is governed by Varshni's formalism in Vis spectral region further affecting their high refractive index properties at the lossless NIR spectral tails. Furthermore, we exploit the measured optical dispersion of ternary WSSe designing ultrathin plano-convex NIR photonic lenses that demonstrate continuous modulation of performance with temperature variation. Our work provides critical insights for the creation of next-generation thermo-driven nanophotonic and optoelectronic devices.

physics.optics↗

arXiv2026

Broadband dielectric permittivity tensor of muscovite for next-generation all van der Waals photonic components

We report a comprehensive determination of the broadband dielectric permittivity tensor of van der Waals (vdW) muscovite also referred to as mica, establishing it as a low-index low-loss platform for ultrathin nanophotonics. Resolving its anisotropic vibrational response and extracting accurate tensor components across broadband ultraviolet (UV) to near-infrared (NIR) spectral region, we show that vdW muscovite exhibits consistently low refractive indices negligible extinction and weak in-plane anisotropy allowing its effective treatment as a uniaxial dielectric in thin-film limits. Leveraging these properties, we design muscovite based vdW heterostructures pairing it MoS2, engineering few-layer distributed Bragg reflectors (DBR) and dichroic beam splitters (DBS) with high efficiency robust optical performance in a broad NIR spectral region achieved with sub-micron thicknesses. Our findings spotlight the high significance of low-index extinctionless vdW crystals, positioning muscovite as a highly perspective atomically flat building block for next-generation, broadband, all-vdW nanophotonic components.

physics.optics↗

arXiv2025

Dielectric permittivity tensor dynamics of in-plane hyperbolic van der Waals MoOCl2 and emergent chiral photonic applications

Van der Waals (vdW) crystals offer unique opportunities for modern nanophotonic applications owing to their intrinsic anisotropic nature. While most of them exhibit uniaxial anisotropy arising from weak out-of-plane vdW interaction, some of their representative families also exhibit an in-plane biaxial anisotropy. Among the latter, outstand vdW oxochlorides with in-plane axes of a different physical character (metallic or dielectric). Here, we present an accurate dynamics of dielectric permittivity tensor components of vdW MoOCl2 in the ultraviolet (UV) to visible (Vis) spectral region partly covering near-infrared (NIR). Addressing its enormously anisotropic optical constants, we focus on another hyperbolicity window of vdW MoOCl2 emerging in the UV spectral region that may potentially unlock rich light-matter interaction effects. Furthermore, we propose an approach towards designing nanoscale handedness preserved Vis light circular polarizers based on twisted helical vdW MoOCl2 heterostructures. Our findings display that vdW MoOCl2 provides a highly promising platform not only for hyperbolic, but also for chiral nanophotonic applications.

physics.optics↗

arXiv2014

The structure of invariants in conformal mechanics

We investigate the integrals of motion of general conformal mechanical systems with and without confining harmonic potential as well as of the related angular subsystems, by employing the SL(2,R) algebra and its representations. In particular, via the tensor product of two representations we construct new integrals of motion from old ones. Furthermore, the temporally periodic observables (including the integrals) of the angular subsystem are explicitly related to those of the full system in a confining harmonic potential. The techniques are illustrated for the rational Calogero models and their angular subsystems, where they generalize known methods for obtaining conserved charges beyond the Liouville ones.

hep-th↗

arXiv2013

Zero-curvature condition in Calogero model

We consider the mutual commutativity of Dunkl operators of the rational Calogero model as zero-curvature condition and calculate the non-local operator, related to these flat connections. This operator has physical meaning of particular scattering matrix of Calogero model and maps the eigenfunctions of Dunkl operator to the wave function of $N$ free particles (plane waves).

math-ph↗

arXiv2010

Jordan-Schwinger Representations and Factorised Yang-Baxter Operators

The construction elements of the factorised form of the Yang-Baxter R operator acting on generic representations of q-deformed sl(n+1) are studied. We rely on the iterative construction of such representations by the restricted class of Jordan-Schwinger representations. The latter are formulated explicitly. On this basis the parameter exchange and intertwining operators are derived.

hep-th↗