Yuri A. Godin

Transmission of 25-Gb/s RZ-DQPSK signals with 25-GHz channel spacing over 1000 km of SMF-28 fiber

We report transmission of nine 25-Gb/s return-to-zero differential quadrature phase-shift keyed (RZ-DQPSK) dense wavelength-division-multiplexing signals with 25-GHz channel spacing over 1000 km of single-mode fiber (SMF-28) in a recirculating loop. The loop uses all erbium-doped fiber amplifiers (EDFAs) and has an amplifier spacing of 100 km with an average loss of 25 dB between EDFAs and a maximum span loss of up to 30 dB. All channels were copolarized launched. No precompensation or postcompensation was employed. To the best of our knowledge, this is the first transmission test of multichannel RZ-DQPSK signals operating at 25 Gb/s with a spectral efficiency of 0.8 b/s/Hz. The transmission distance is limited by amplified spontaneous emission noise due to the high span losses. Nevertheless, our result indicates that upgrading the capacity of long-haul terrestrial systems using RZ-DQPSK modulation format should be feasible.

Effective complex permittivity tensor of a periodic array of cylinders

We determine the effective complex permittivity of a two-dimensional composite, consisting of an arbitrary doubly periodic array of identical circular cylinders in a homogeneous matrix, and whose dielectric properties are complex-valued. Efficient formulas are provided to determine the effective complex permittivity tensor which are in excellent agreement with numerical calculations. We also show that in contrast to the real-valued case, the real and imaginary parts of the effective complex-valued tensor can exhibit non-monotonic behavior as functions of volume fraction of cylinders, and can be either greater or less than that of the constituents.

The effective conductivity of a periodic lattice of circular inclusions

We determine the effective conductivity of a two-dimensional composite consisting of a doubly periodic array of identical circular cylinders within a homogeneous matrix. The problem is reduced to the solution of an infinite system of linear equations. The effective conductivity tensor is obtained in the form of the series expansion in terms of the volume fraction of the cylinders whose coefficients are determined exactly. Results are illustrated by examples.

The effect of disorder on the wave propagation in one-dimensional periodic optical systems

The influence of disorder on the transmission through periodic waveguides is studied. Using a canonical form of the transfer matrix, we investigate the dependence of the Lyapunov exponent γ on the frequency ν and magnitude of the disorder σ. It is shown that in the bulk of the bands γ ∼ σ2, while near the band edges it has order γ ∼ σ2/3. This dependence is illustrated by numerical simulations.

Spectral Properties of Thin-Film Photonic Crystals

We study spectral properties of three-dimensional photonic crystals formed by a periodic array of air cubes separated by a thin film of optically dense dielectric material. The thickness

Propagation of longitudinal waves in a random binary rod

\delta

Wave propagation in a one-dimensional randomly perturbed periodic medium

of the dielectric component is assumed to be small, whereas its permittivity

On the Determination of the Boundary Impedance from the Far Field Pattern

\varepsilon

The inverse scattering problem for the difference operators: The decomposition method

is large. The spectrum of the photonic crystal is studied as

A simple method for solving the inverse scattering problem for the difference Helmholtz equation

\delta \rightarrow 0