Energy characteristics of the superposition TE- and TM-polarized electromagnetic Bessel beams are studied. For some phase differences between TE TM waves components Poynting vector vary in sign. We call this situation "negative propagation," because locally beam may behave like a wave propagating direction opposite to conventional one. predict following phenomena, which should confirm negative propagation: reflection from circular aperture unusual movement microparticles beam.

Using the Maxwell-Bloch equations for resonantly absorbing and amplifying media, we study temporal dynamics of light propagation through PT-symmetric structures with alternating loss gain layers. This approach allows us to precisely describe response structure near exceptional points PT-symmetry breaking phase transition and, in particular, take into account nonlinear effect saturation broken state. We reveal that this latter state multilayer system possesses a lasing-like behavior releasing...

Non-Hermitian photonic systems with loss and gain attract much attention due to their exceptional abilities in molding the flow of light. Introducing asymmetry PT-symmetric system perfectly balanced gain, we reveal mechanism transition from quasibound state continuum (quasi-BIC) simultaneous coherent perfect absorption (CPA) lasing a layered structure comprising epsilon-near-zero media. Two types (geometric non-Hermitian) are analyzed scattering matrix technique. The effect CPA-lasing...

We report on the propagation dynamics of Airy light beams under nonparaxial conditions. The partial waves forming beam can be divided into two parts, first which contains only propagating waves, while second part consists evanescent waves. In this Letter we propose concept beam. analyze structure ideal beam, initial profile has form, its spectral decomposition Also, discuss refraction through an interface and investigate field transmitted

$\mathcal{PT}$ symmetry is a unique platform for light manipulation and versatile use in unidirectional invisibility, lasing, sensing, etc. Broken unbroken $\mathcal{PT}$-symmetric states non-Hermitian open systems are described by scattering matrices. A multilayer structure, as simplest example of the system, has no certain definition matrix, since output ports can be permuted. The uncertainty exceptional points bordering $\mathcal{PT}$-symmetry-broken poses an important problem, because...

Bound states in the continuum (BICs) enable unique features tailoring light-matter interaction on nanoscale. These radiationless localized drive theoretically infinite quality factors and lifetimes for modern nanophotonics, making room a variety of emerging applications. Here we use peculiar properties possessed by so-called $\mathcal{PT}$ symmetric optical structures to propose novel mechanism quasi-BIC manifestation governed symmetry breaking. In particular, study regularities spontaneous...

Unique and highly tunable optical properties of $\mathcal{PT}$-symmetric systems metamaterials enable a plenty entirely new linear nonlinear phenomena with numerous applications, e.g., for designing subdiffraction lenses, nonreciprocal devices, etc. Therefore, the artificial media $\mathcal{PT}$ symmetry attract ever-increasing attention are now subject intensive investigations. One commonly used methods providing information about response nanostructural is so-called effective medium...

We solve the problem of ultrashort pulse propagation in a two-level medium beyond rotating-wave (RWA) and slowly varying-envelope approximations. The method solution is based on Maxwell-Bloch equations represented form that allows one to switch between RWA general (non-RWA) cases framework single numerical algorithm. Using this method, effect subcycle (containing less than period field oscillations) was analyzed. It shown for such short pulses, clear breakdown area theorem occurs pulses...

Propagation of ultrashort optical pulses in a dense resonant medium is considered the semiclassical limit. In our analysis, we place emphasis on several main points. First, study transformations spectra process pulse propagation and interactions with another pulse. The second point involves transient processes (including compression) connected self-induced transparency soliton formation inside medium. Finally, third aspect collisions co- counterpropagating last case, investigation symmetric...

Intensive light pulse interaction with a dense resonant medium is considered. The possibilities of optical switching and compression at realistic parameters the are analyzed. Pulse-shape transformation in different photonic-band-gap structures containing studied. In particular, effect dispersion compensation due to nonlinear reported. possibility control another considered schemes copropagating counterpropagating pulses. It shown that photonic crystal makes controlling more effective, least case

Using the transfer-matrix approach and solving time-domain differential equations, we analyze loss compensation mechanism in multilayer systems composed of an absorbing transparent conductive oxide dielectric doped with active material. We reveal also another regime possibility enhanced transmission suppressed reflection originating from resonant properties multilayers. For obliquely incident evanescent waves, such under turns into reflectionless regime, which is similar to that observed...

Structured environment controls dynamics of light-matter interaction processes via modified local density electromagnetic states. In typical scenarios, where nanosecond-scale fluorescent are involved, mechanical conformational changes the during can be safely neglected. However, slow decaying phosphorescent complexes (e.g. lanthanides) efficiently sense micro- and millisecond scale motion near-field interactions. As result, lifetime statistics inherit information about nano-scale motion....

We study inelastic collisions of counter-propagating self-induced transparency solitons in a homogeneously broadened two-level medium. The energy the pulse can be almost totally absorbed medium due to asymmetric collision with properly chosen control pulse. state thus prepared demonstrates property an all-optical diode which transmits pulses from one direction and blocks another. saturation process controlled absorption effect, local-field correction influence, parameter ranges for action...

We report on a bistable light transmission through bilayer "fish-scale" (meander-line) metamaterial. It is demonstrated that an all-optical switching may be achieved nearly the frequency of high-quality-factor Fano-shaped trapped-mode resonance excitation. The nonlinear interaction two closely spaced resonances in structure composed with Kerr-type dielectric slab analyzed both and time domains. these react differently applied intense which leads to destination multistable transmission.

Using numerical simulations, we study propagation of ultrashort light pulses in an inhomogeneously broadened two-level medium. There are two main issues our study. The first one concerns the transient process self-induced transparency soliton formation, particular, compression pulse which seems to be more effective case homogeneous broadening. second question deals with collisions counter-propagating solitons. It is shown that level inhomogeneous broadening has a substantial effect on...

Non-Hermitian photonics based on combining loss and gain media within a single optical system provides number of approaches to control generate the flow light. In this paper, we show that by introducing non-Hermitian perturbation into with constituents, high-quality resonances known as trapped modes can be excited without need change symmetry unit cell geometry. To demonstrate idea, consider widely used all-dielectric planar metamaterial whose consists pair rectangular nanoantennae made...

Virtual gain refers to the simulation of real light amplification using radiation with exponentially decaying amplitude so that its complex frequency corresponds scattering pole. We study theoretically virtual in a two-level resonant medium for different regimes light-matter interaction depending on intensity. show at pole can be most clearly observed low intensities, when is absorbing, contrast saturated high intensities. The efficiency tuned intensity and controlled dynamically through...

We consider the optical response of a one-dimensional photonic crystal with dense resonant medium as defect. Using iteration matrix approach, we calculate intensity distribution in this structure and reflection transmission properties it. discuss influence on bistable behavior both within outside region intrinsic bistability. Finally compare our results case without taking into account near dipole-dipole interaction.

In this note we give semiclassical consideration of the role pulse duration in observation local field effects regime optical switching. We show that main parameter governing influence is ratio peak Rabi frequency corresponding to medium inversion and Lorentz medium. To obtain significant effect, should be near unity valid only for long enough pulses. also discuss relaxation shape processes.

We theoretically study the effect of pulse trapping inside one-dimensional photonic crystal with relaxing cubic nonlinearity. analyze dependence light localization on intensity and explain its physical mechanism as connected formation dynamical nonlinear cavity structure. search for range optimal values parameters (relaxation time duration) show that can be observed only positive nonlinearity coefficients. suppose this useful realization optical memory limiting.

The idea of asymmetric light transmission through a photonic crystal with relaxing Kerr nonlinearity is presented. This based on the symmetry breaking due to self-trapping intensive pump pulse inside structure. As result, secondary (probe) pulses perturbed can be observed. cases short and long (quasi-continuous) probe are considered.