This spool was acquired from Bookham (formal Nortel laser group). Spool length and insertion loss (including one connector loss) are tested in our lab as shown in last photo below. See specification and more technical info in pdf, htm, and txt links below. Dispersion-shifted fiber (DSF), specified in ITU-T G.653, is a type of single-mode optical fiber with a core-clad index profile tailored to shift the zero-dispersion wavelength from the natural 1300 nm in silica-glass fibers to the minimum-loss window at 1550 nm. The group-velocity or intramodal dispersion which dominates in single-mode fibers is comprised of both material and waveguide dispersion. Waveguide dispersion can be made more negative by changing the index profile and thus be used to offset the fixed material dispersion, shifting or flattening the overall intramodal dispersion. This is advantageous because it allows a communication system to possess both low dispersion and low attenuation. However, when used in wavelength division multiplexing systems, dispersion-shifted fibers can suffer from four-wave mixing which causes intermodulation of the independent signals. As a result nonzero dispersion shifted fiber is often used. DSF: To minimize chromatic dispersion at 1550 nm, a new fiber called dispersion-shifted fiber (DSF) was introduced in the early 1980's. By changing the index profile and reducing the core radius, fiber designers were able to move ?0 from the 1310 nm window to the 1540 to 1560 nm window. Though effective in greatly reducing chromatic dispersion effects, which limits bandwidth, the positioning of ?0 in close proximity to the operating wavelengths resulted in a tendency to a nonlinear distortion effect called four wave mixing (FWM). This is especially troublesome in DWDM applications with more than eight wavelengths. Typical losses range from 0.25 to 0.30 dB/km. Note: Standard DSF fiber has a ?0 of 1557.5 ±12.5 nm (i.e. 1544.5 nm to 1569.5 nm).