Presence Of Random Inhomogeneities Research Articles

Influence of the polarization mode dispersion on the propagation of ultrashort optical pulses in single-mode fiber lightguides with very weak linear birefringence and random inhomogeneities

We consider the influence of the polarization mode dispersion, which is stipulated by the presence of random inhomogeneities in single-mode fiber lightguides, on the propagation of ultrashort optical pulses in the fiber communication lines with very weak linear birefringence. Evolution of the envelope of ultrashort optical pulses and their spectra as functions of the length of a single-mode fiber lightguide with very weak linear birefringence and random inhomogeneities are obtained by the method of mathematical simulation. An increase in the pulse duration is shown to be proportional to the square root of the length of a single-mode fiber lightguide. The numerical-simulation results are compared with the results of experimental measurements of the polarization mode dispersion.

Mathematical Modeling of Random Coupling between Polarization Modes in Single-Mode Optical Fibers: XII. Dependence of the Zero Drift in Fiber Ring Interferometers in Orthogonal Polarization Modes on the Range of Temperature Variation in an Optical Fiber

Temperature dependences of the zero drift in a fiber ring interferometer (FRI) without a polarizer in the presence of random inhomogeneities in a single-mode optical fiber in the FRI loop are obtained by numerical simulation. The results are compared with known experimental data. It is shown that FRIs using a superluminescent diode as a source of nonmonochromatic radiation and a loop made of a single-mode optical fiber with weak linear birefringence can find application as low-accuracy fiber-optic gyroscopes and FRIs with a loop made of a single-mode optical fiber with strong linear birefringence can be used as medium-accuracy fiber-optic gyroscopes.

Mathematical Modeling of Random Coupling between Polarization Modes in Single-Mode Optical Fibers: Integrated Statistical Properties of Polarization Modes of Single-Mode Optical Fibers in the Presence of Random Inhomogeneities

Mathematical Modeling of Random Coupling between Polarization Modes in Single-Mode Optical Fibers: Integrated Statistical Properties of Polarization Modes of Single-Mode Optical Fibers in the Presence of Random Inhomogeneities

Mathematical modeling of random coupling between polarization modes in single-mode optical fibers: Integrated statistical properties of polarization modes of single-mode optical fibers in the presence of random inhomogeneities

Using mathematical modeling, an explicit form is found for the Jones matrix of a segment of a single-mode optical fiber with random inhomogeneities, whose length is considerably greater than the correlation length of random inhomogeneities. It is shown that parameters of this matrix are of a statistical nature. A rational representation of the matrix is proposed. It is shown that, under certain conditions, one of the matrix parameters may be treated as constant, whereas the other parameter is assumed to be continuously distributed on the interval [0, 2π]. As the latter parameter is changed, which corresponds to a change from one random realization of inhomogeneities in a single-mode fiber to another, the ellipticity and the azimuth of the major axis of the polarization ellipse of natural polarization modes of a single-mode fiber simultaneously change.

Intensity calculations in a random medium with channel velocity profile using coherence theory

We use a three scale expansion to calculate the intensity distribution of acoustic radiation propagating in a sound channel in the presence of random inhomogeneities. We develop equations which show how the coherence function varies along the characteristic rays (identical to the rays of geometrical acoustics in the parabolic approximation). Solving these equations we obtain an expression for the vertical intensity distribution resulting from an acoustic beam propagating in a random medium with a sound velocity profile. When the fluctuations of the medium are statistically homogeneous and isotropic, this expression is simplified for two limiting cases: weak scattering and strong scattering. We present an example of high‐frequency scattering in a random medium with a mean cubic profile. We calculate the intensity corrections in the vicinity of a caustic under typical ocean conditions. The results of the corrected intensity distribution are compared with the uncorrected intensity results obtained previously.

Propagation of an unstable spectrum of plasmons in the presence of random inhomogeneities

A one-dimensional stochastic kinetic equation for the propagation of unstable plasmons (Langmuir modes) in the presence of large scale random spatial fluctuations is presented, within the frame of the WKB approximation, and then solved. Using probabilistic arguments, an effective growth rate is evaluated, which turns out to be much smaller than the plasmon growth rate in the absence of fluctuations. The theory is then applied to the beam-plasma kinetic instability and to the stimulated photon-plasmon interaction. The former case exhibits a shift of the turbulent plasmon spectrum toward larger wavenumbers. The latter case shows a strong reduction in the efficiency of the stimulated process (i.e., much smaller growth rate) and the removal of the strong asymmetry inherent in this problem.