arXiv subjects

Denis Novitsky

Publications and source records attributed to Denis Novitsky.

31 records · Page 2Linked to original sources

arXiv2015

Ultrashort pulses in an inhomogeneously broadened two-level medium: soliton formation and inelastic collisions

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

physics.optics↗

arXiv2014

Pulse propagation in one-dimensional disordered photonic crystals: Interplay of disorder with instantaneous and relaxing nonlinearities

Propagation of ultrashort light pulses in disordered multilayers is studied by using numerical simulations in time domain. We consider cases of instantaneous and noninstantaneous Kerr nonlinearities of the structure materials. The competitive nature of disorder and nonlinearity is revealed on the long and short timescales. We also pay special attention to the effect of pulse self-trapping in the photonic crystal with relaxing nonlinearity and show the dependence of this effect on the level of disorder. We believe that the results reported here will be useful not only in the field of optics but also from the standpoint of the general problem of classical waves propagation in nonlinear disordered periodic media.

physics.optics↗

arXiv2013

Effects of pulse collisions in a multilayer system with noninstantaneous cubic nonlinearity

The numerical simulations of an ultrashort pulse propagation in a one-dimensional nonlinear photonic crystal are carried out. It is known that the relaxation of cubic nonlinearity is the reason for the effect of pulse self-trapping in such multilayer system. In this paper we study further implications of this effect. It is shown that the trapped light absorbs additional low-intensity pulses which cannot be self-trapped \textit{per se}. On the other hand, such low-intensity pulses are subject of the so-called induced trapping when light gets trapped due to a collision of two such pulses. We consider the conditions for this effect in both cases of co- and counter-propagating pulses.

physics.optics↗

arXiv2012

Propagation of subcycle pulses in a two-level medium: Area-theorem breakdown and pulse shape

We solve the problem of ultrashort pulse propagation in a two-level medium beyond the rotating-wave (RWA) and slowly-varying-envelope approximations. The method of solution is based on the Maxwell--Bloch equations represented in the form that allows one to switch between RWA and general (non-RWA) cases in the framework of a single numerical algorithm. Using this method, the effect of a subcycle pulse (containing less than a single period of field oscillations) on the two-level medium was analyzed. It is shown that for such short pulses, the clear breakdown of the area theorem occurs for the pulses of large enough area. Moreover, deviations from the area theorem appear to be strongly dependent on the pulse shape that cannot be observed for longer few-cycle pulses.

physics.optics↗

arXiv2012

Asymmetric light transmission through a photonic crystal with relaxing Kerr nonlinearity

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

physics.optics↗

arXiv2012

Controlled absorption and all-optical diode action due to collisions of self-induced transparency solitons

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

physics.optics↗

arXiv2011

Spectral transformations in the regime of pulse self-trapping in a nonlinear photonic crystal

We consider interaction of a femtosecond light pulse with a one-dimensional photonic crystal with relaxing cubic nonlinearity in the regime of self-trapping. By use of numerical simulations, it is shown that, under certain conditions, the spectra of reflected and transmitted light possess the properties of narrow-band (quasi-monochromatic) or wide-band (continuum-like) radiation. It is remarkable that these spectral features appear due to a significant frequency shift and occur inside a photonic band gap of the structure under investigation.

physics.optics↗

arXiv2011

Femtosecond pulses in a dense two-level medium: Spectral transformations, transient processes, and collisional dynamics

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

physics.optics↗

arXiv2010

Pulse trapping inside one-dimensional photonic crystal with relaxing cubic nonlinearity

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

physics.optics↗

arXiv2009

Effect of frequency detuning on pulse propagation in one-dimensional photonic crystal with a dense resonant medium: application to optical logic

We consider propagation of light pulses detuned from the atomic resonance in a dense two-level medium and photonic structures with it. The large density of the medium is important to decrease spatial scale of such nonlinear effects as pulse compression, though it does not provide any fundamentally new phenomena as compared to dilute media. Frequency detuning decreases the effectivity of such nonlinear phenomena as pulse compression and dispersion spreading compensation as well. We propose simple logic gates based on interaction between two pulses in one-dimensional nonlinear photonic crystal. It turned out, that frequency detuning is necessary to obtain ultrafast AND gate, while OR and NOT gates can be realized in the system without detuning.

physics.optics↗

arXiv2009

Compression of an intensive light pulse in a dense resonant medium and photonic-band-gap structures containing it

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

physics.optics↗

arXiv2009

Evanescent Airy beams

In this Letter we propose the concept of the evanescent Airy beam. We analyze the structure of the ideal evanescent Airy beam, which initial profile has the Airy form, while the spectral decomposition consists of only evanescent partial waves. Also, we discuss the refraction of the Airy beam through the interface and investigate the field of the transmitted evanescent Airy beam.

physics.optics↗

arXiv2009

Non-paraxial Airy beams

We report the propagation dynamics of Airy light beams under non-paraxial conditions. It is studied using the general approach which deals with Fourier expansion of the beam. We show the transformation of the beam from the Airy form as the paraxiality parameter decreases. The role of evanescent waves in non-paraxial regime is discussed.

physics.optics↗