arXiv subjects

Valeriy I. Kondratyev

Publications and source records attributed to Valeriy I. Kondratyev.

3 recordsLinked to original sources

arXiv2025

Nonlinear near-field spectroscopy of exciton-polaritons in a van der Waals layered waveguide

Layered van der Waals materials offer novel opportunities for on-chip waveguiding and development of integrated photonic circuits. In the strong light-matter coupling regime, their nonlinear response can be significantly enhanced, which is crucial for developing active photonic devices. However, probing the nonlinearity of waveguide modes in subwavelength-thick structures is challenging as they are not directly accessible from far-field. Here we apply a novel nonlinear near-field spectroscopic technique based on a GaP solid immersion lens and femtosecond laser excitation to study nonlinearity of guided modes in monolayer WS$_2$ encapsulated in hBN under the strong light-matter coupling regime. We reveal formation of exciton-polaritons with $\sim 50$ meV Rabi splitting and demonstrate a pump-induced transition from strong to weak coupling. Our results show that exciton resonance saturation and broadening lead to an efficient nonlinear response of guided polaritons, which can be employed for developing compact van der Waals photonic switches and modulators.

physics.optics↗

arXiv2024

Electrostatic control of nonlinear photonic-crystal polaritons in a monolayer semiconductor

Integration of 2D semiconductors with photonic crystal slabs provides an attractive approach to achieve strong light--matter coupling and exciton-polariton formation in a planar chip-compatible geometry. However, for the development of practical devices, it is crucial that the polariton excitations in the structure are easily tunable and exhibit strong nonlinear response. Here we study neutral and charged exciton-polaritons in an electrostatically gated planar photonic crystal slab with an embedded monolayer semiconductor MoSe$_2$ and experimentally demonstrate strong polariton nonlinearity, which can be tuned via gate voltage. We find that modulation of dielectric environment within the photonic crystal results in the formation of two distinct resonances with significantly different nonlinear response, which enables optical switching with ultrashort laser pulses. Our results open new avenues towards development of active polaritonic devices in a compact chip-compatible implementation.

cond-mat.mes-hall↗

arXiv2023

Probing and control of guided exciton-polaritons in a 2D semiconductor-integrated slab waveguide

Guided 2D exciton-polaritons, resulting from the strong coupling of excitons in semiconductors with non-radiating waveguide modes, provide an attractive approach towards developing novel on-chip optical devices. These quasiparticles are characterized by long propagation distances and efficient nonlinear interaction but cannot be directly accessed from the free space. Here we demonstrate a powerful approach for probing and manipulating guided polaritons in a Ta2O5 slab integrated with a WS2 monolayer using evanescent coupling through a high-index solid immersion lens. Tuning the nanoscale lens-sample gap allows for extracting all the intrinsic parameters of the system. We also demonstrate the transition from weak to strong coupling accompanied by the onset of the motional narrowing effect: with the increase of exciton-photon coupling strength, the inhomogeneous contribution to polariton linewidth, inherited from the exciton resonance, becomes fully lifted. Our results enable the development of integrated optics employing room-temperature exciton-polaritons in 2D semiconductor-based structures.

physics.optics↗