Conversion of waveguide modes in a periodic optical fiber

We investigate the distinctive features of the propagation and interaction of linearly polarized modes of an unperturbed step-index fiber, perturbed by a periodic distribution of the dielectric constant along the axis of the optical fiber. An analysis is made for unidirectional and opposite modes and two-mode excitation of the optical fiber. Ul’yanovsk Branch, Moscow State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, p. 40–46, March, 1998.     

Dynamical regimes of conversion of magnetogyrotropic waveguide modes in the region of ferromagnetic resonance

The dynamical conversion of magnetogyrotropic waveguide modes in the regime of uniform spin precession at large angles is studied. It is shown that the nutation of the magnetization vector due to the precession frequency doubling results in dependence of the light modulation amplitude on the polarization of the microwave field. The contribution of harmonics with frequencies that are multiples of the fundamental precession frequency of ferromagnetic resonance to the total mode-conversion efficiency is analyzed for different lengths of the waveguide and different equilibrium orientations of the magnetization. State University, Ulianovsk, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 5, pp. 651–663, May, 1998.     

Propagation and transformation of a frequency-modulated pulse in a periodically nonuniform fiber

The specific features of transformation of the time envelopes of mode components of a pulse with allowance for the material and intermode dispersion and different types of fiber excitation are studied for a Gaussian frequency-modulated pulse propagating in a two-mode periodic fiber. State University, Ul’yanovsk, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 6, pp. 792–802, June, 1998.     

Dynamics of a two-wave packet in a nonlinear optical fiber at detuning from phase matching

The effect of detuning from phase matching on the dynamics of a wave packet consisting of two unidirectional strongly interacting modes in a fiber with Kerr nonlinearity is considered. The effective parameters of dispersion and nonlinearity are analyzed for a wave packet that can be represented by a single partial pulse.     

Modulation instability of pulsed radiation in an optical waveguide in the presence of the traveling refractive index wave

The conditions for the onset of modulation instability of wave packets in an optical waveguide in the presence of the traveling refractive index wave are investigated. An expression governing the growth rate of a small harmonic perturbation at the early development stage of the modulation instability is obtained. Based on numerical analysis, the behavior of the wave packet at the developed modulation instability stage is studied for different parameters of the waveguide and the refractive index wave.     

Modulation instability of wave packets in a Gires–Tournois interferometer

We study the specific features of the perturbation dynamics of a wave packet in a Gires–Tournois interferometer. We obtain a dispersion relationship that relates the perturbation parameters to the parameters of the structure and pump wave, the analytical expressions for the gain increment of a harmonic perturbation and other important characteristics that determine the dynamics of the modulation instability of the reflected wave. Based on numerical simulation, we plot the dependences of the dispersion and nonlinearity parameters and the gain increment on the spacing between the interferometer mirrors, the angle of incidence of the radiation onto the mirrors, and the radiation intensity.     

A multipole analysis of the apparent motion of reference radio sources

In this paper, the apparent motions of quasars, which are the reference sources of the international celestial reference system (ICRS), are analyzed. Kinematic parameters from four catalogs compiled by different research groups are used. Apparent motions are expanded on a special set of vector functions on the sphere that are an irreducible representation of the rotation group O(3). The degree of the noninertiality of the barycentric reference system caused by the rotation of the solar system around the galactic center is estimated according to expansion coefficients. The direction and magnitude of the acceleration vector are calculated and compared with the alternative estimates. This method is discussed as a way to test Newton’s law on a large scale.     

Interference of Counterpropagating Waves in a “Graphene–Dielectric” Planar Lamellar Structure

Optics and Spectroscopy - The incidence of two coherent waves traveling in opposite directions on opposite surfaces of a planar layered-periodic graphene–dielectric structure has been...     

Dynamics of a Wave Packet of Whispering-Gallery-Mode Type in an Optical Waveguide in the Presence of a Traveling Refractive-Index Wave

It is demonstrated that strong ultrafast modulation of a tunneling wave packet of the whispering-gallery-mode type can be implemented in a cylindrical optical waveguide exhibiting spatiotemporal inhomogeneity induced by a travelling refractive-index wave. The corresponding optical waveguides can be used for efficient generation of picosecond and subpicosecond laser pulses.