Lucent Technologies Inc.

At&t Bell Laboratories

Raymond Bradfield Kummer

David Kalish

Andrew Roman Chraplyvy

William Alfred Reed

Bernard Raymond Eichenbaum

Arthur F Judy

Janice Bilecky Haber

David Wayne Peckham

Gary Patrick Emery

Marcus W Shute, Sr

A high-capacity optical fiber network &lsqb;,&rsqb; includes wavelength-division multiplexing (WDM) within the 1.4 micron (&mgr;m) wavelength region (i.e., 1335-1435 nm). Such a system includes optical fiber &lsqb;,&rsqb; whose peak loss in the 1.4 &mgr;m region is less than its loss at 1310 nm. The optical fiber has a zero dispersion wavelength (&lgr;,) at about 1310 nm, and linear dispersion between about 1.5 and 8.0 ps/nm-km within the 1.4 &mgr;m region. At least three WDM channels operate at 10 Gb/s in the 1.4 &mgr;m wavelength region and have a channel separation of 100 GHz. In one illustrative embodiment of the invention, a broadcast television channel, having amplitude modulated vestigial sideband modulation, simultaneously operates in the 1.3 &mgr;m region (i.e., 1285-1335 nm) and/or the 1.55 &mgr;m region (i.e., 1500-1600 nm). In another embodiment of the invention, 16 digital data channels are multiplexed together in the 1.55 &mgr;m region, each channel operating at about 2.5 Gb/s. Raman amplifiers &lsqb;,&rsqb; are used for amplification in the 1.3 &mgr;m and the 1.4 &mgr;m wavelength regions, whereas an Erbium amplifier &lsqb;,&rsqb; is used for amplification in the 1.55 &mgr;m wavelength region.

Arrangement of optical fiber segments for minimizing effect of nonlinearities

Simultaneous dense WDM operation in both the 1310 nm and 1550 nm transparency windows of silica-based optical fiber, is enabled by a fiber design providing for nulled dispersion within a critically positioned wavelength range. Design provides for values of dispersion in both windows sufficiently low for desired per-channel bit rate, and, at the same time, sufficiently high to maintain effects of non-linear dispersion within tolerable limits for WDM operation. Fiber fabrication and system design are described.

Dual window WDM optical fiber communication

Variations in bending loss for relatively small radii bends along a length of optical fiber (26) are determined by using an optical time domain reflectometer (20) to measure the backscattering power as a function of distance along the fiber in one direction along the length of fiber by launching light energy into one end of the fiber. Then the backscattering power is measured as a function of distance along the fiber in the opposite direction from an opposite end by launching light energy into an opposite end of the fiber. Mathematical representations of backscattering forward and reverse signals for corresponding points along the length of the fiber are added to provide a quantity which is related to mode field diameter of the fiber. Variations in the mode field diameter are indicative of variations in the bending loss along the length of fiber. By measuring the bending loss at the end points of the length of fiber, the absolute bending loss along the length of fiber can be estimated from the above quantity.

Methods of and apparatus for measuring bending loss along a length of

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Lilburn, GA, United States of America

Raymond Bradfield Kummer