Long-haul Transmission Line Research Articles

Few-mode multicore fibers for long-haul transmission line

Abstract Few-mode multicore fibers (FM-MCFs) that enable dense space-division multiplexing (DSDM) have the potential to drastically improve the fiber capacity. In designing the FM-MCFs, several issues that originate from multicore fibers and few-mode fibers must be considered. In this paper, these design issues such as inter-core crosstalk (IC-XT) and dispersion mode delay (DMD) are discussed. A three-mode 12-core fiber with low-DMD low-IC-XT achieves long-haul DSDM transmission over 500 km. The design concept, fiber design, and characteristics of the fabricated three-mode 12-core fiber are also described.

Transmission over large-core few-mode photonic crystal fiber using distance-independent modal dispersion compensation technique

We propose a transmission distance-independent technique for modal dispersion compensation over few-mode fiber that uses a single-input multiple-output configuration and adaptive equalization. Our technique can compensate for the modal dispersion of a signal with 1-tap FIR filters regardless of the amount of modal delay difference, and enables us to utilize fiber with a large core and few modes as a long-haul transmission line. We also show numerically the advantage of few-mode photonic crystal fiber (PCF) for realizing a larger effective area (A(eff)), and finally we report a transmission over a large-core two-mode PCF with A(eff)>280 μm(2).

Noise in distributed erbium-doped fibers

Theoretical limits in noise figure for a long-haul transmission line based on lumped amplification are contrasted with distributed amplification. The latter results in a reduction of approximately 60% of the required number of pump power stations. The distributed optical amplification is provided by an erbium-doped fiber and comparisons of aluminum and germanium as codopant materials are shown. The pump power consumption and noise figure are analyzed with respect to the background loss.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

WT4 Millimeter Waveguide System: Mechanical Design of Sheathed Waveguide Medium

The mechanical design of the sheathed waveguide medium for the WT4 System provides means for the fusion joining of waveguide modules into a continuous transmission line and for limiting the distortions added by the joining and installation processes. In addition the fusion-joined steel sheath guarantees a much higher degree of protection for the medium than is present in any of the existing long-haul transmission lines. A summary of the development program of the sheathed waveguide medium used in the recent field evaluation test is presented herein. Results are given of the study conducted to establish the welding procedures used and steps in the evolution of the welded coupling design are reviewed. A discussion is given of the behavior of the two-stage mechanical filter that attenuates the effects of the irregular soil forces acting on the sheath. Estimates of the field test losses attributable to the joining and installation processes are also given.