arXiv subjects

Yuriy Akimov

Publications and source records attributed to Yuriy Akimov.

6 recordsLinked to original sources

arXiv2025

Probing dynamics of time-varying media: Beyond abrupt temporal interfaces

This work investigates the effects of time-varying media, where optical properties change over time, on electromagnetic wave propagation, focusing on plane waves and free-electron evanescent waves. We introduce a switching parameter, $\tau$, to model ultrafast switching in the femtosecond to nanosecond range. For plane-wave incidence at angular frequency $\omega_0$, we derive a generalized expression for the backward-to-forward flux ratio as a function of $\omega_0$ and $\tau$, aligning with recent experimental data and providing a unified interpretation framework. For free-electron incidence, we observe intensity saturation in temporal transition radiation at $I_{\textrm{max}}$ for $\tau \leq \tau_{\textrm{0}}$, with both $I_{\textrm{max}}$ and $\tau_{\textrm{0}}$ depending on electron speed. These results highlight the importance of precise $\tau$ control in experiments to probe time-varying media effectively.

physics.optics↗

arXiv2024

Eigenmode Decomposition Method for Full-Wave Modeling of Microring Resonators

We develop a theoretical predictive model for an all-pass ring resonator that enables the most complete description of linear coupling regimes. The model is based on eigenmode decomposition of Maxwell's equations with full account of the confined and leaky modes, as opposed to the existing phenomenological methods restricted to the confined modes only. This model enables quantitative description of all-pass ring resonators and provides insights into the physics underlying microring-waveguide coupling. We experimentally validate the model using transmission measurements in the linear regime of aluminium nitride resonators. The developed model is then used to explore the field enhancement in microrings crucial for nonlinear photonic applications.

physics.optics↗

arXiv2022

Light-matter interaction problem in classical and quantum optics

Understanding of light-matter interaction is a keystone in mastering classical and quantum optics. This paper gives an overview of the fundamental principles used in these two fields for description of light-matter interaction. By exploring the simplest type of matter composed of charge-free particles bearing magnetic moments only, differences in the fundamental principles of classical and quantum optics are discussed and clarified.

physics.gen-ph↗

arXiv2021

Photon model of light: Revision of applicability limits

The photon model of light has been known for decades to be self-inconsistent and controversial theory with numerous intrinsic conflicts. This paper revises the model and explores its applicability for description of classical electromagnetic fields. The revision discloses that the photon model fails for fields in current-containing domains, as well as for near fields in current-free regions. This drastically changes the hierarchy of optics theories and the entire landscape of physics. In particular, quantum optics appears to be not the most advanced theory, as it is commonly thought, but just an improved version of geometrical optics with limited applicability, while quantum electrodynamics turns out to provide a truncated description of electromagnetic interactions.

physics.gen-ph↗

arXiv2020

Demonstration of second harmonic generationin gallium phosphide nano-waveguides

We designed, fabricated and tested gallium phosphide (GaP) nano-waveguides for second harmonic generation (SHG). We demonstrate SHG in the visible range around 655 nm using low power continuous-wave pump in the optical communication O-band. Our structures utilize modal phase matching, such that lower order eigenmodes of the pump are phase matched to higher order eigenmodes of the second harmonic. We observe phase matched SHG for different combinations of interacting modes by varying the widths of the waveguides and tuning the wavelength of the pump. The presented results contribute to the development of integrated photonic platforms with efficient nonlinear wave-mixing processes for classical and quantum applications.

physics.optics↗

arXiv2019

Control of LED Emission with Functional Dielectric Metasurfaces

The improvement of light-emitting diodes (LEDs) is one of the major goals of optoelectronics and photonics research. While emission rate enhancement is certainly one of the targets, in this regard, for LED integration to complex photonic devices, one would require to have, additionally, precise control of the wavefront of the emitted light. Metasurfaces are spatial arrangements of engineered scatters that may enable this light manipulation capability with unprecedented resolution. Most of these devices, however, are only able to function properly under irradiation of light with a large spatial coherence, typically normally incident lasers. LEDs, on the other hand, have angularly broad, Lambertian-like emission patterns characterized by a low spatial coherence, which makes the integration of metasurface devices on LED architectures extremely challenging. A novel concept for metasurface integration on LED is proposed, using a cavity to increase the LED spatial coherence through an angular collimation. Due to the resonant character of the cavity, extending the spatial coherence of the emitted light does not come at the price of any reduction in the total emitted power. The experimental demonstration of the proposed concept is implemented on a GaP LED architecture including a hybrid metallic-Bragg cavity. By integrating a silicon metasurface on top we demonstrate two different functionalities of these compact devices: directional LED emission at a desired angle and LED emission of a vortex beam with an orbital angular momentum. The presented concept is general, being applicable to other incoherent light sources and enabling metasurfaces designed for plane waves to work with incoherent light emitters.

physics.optics↗