In an optical fiber, the material dispersion coefficient, M(λ), characterizes the amount of pulse broadening by material dispersion per unit length of fiber and per unit of spectral width. It is usually expressed in picoseconds per (nanometre·kilometre).
For many optical fiber materials, M(λ) approaches zero at a specific wavelength λ0 between 1.3 and 1.5 μm. At wavelengths shorter than λ0, M(λ) is negative and increases with wavelength; at wavelengths longer than λ0, M(λ) is positive and decreases with wavelength.
Pulse broadening caused by material dispersion in a unit length of optical fiber is given by the product of M(λ) and spectral width (Δλ).
Famous quotes containing the words material and/or dispersion:
“This is the essential distinction—even opposition—between the painting and the film: the painting is composed subjectively, the film objectively. However highly we rate the function of the scenario writer—in actual practice it is rated very low—we must recognize that the film is not transposed directly and freely from the mind by means of a docile medium like paint, but must be cut piece-meal out of the lumbering material of the actual visible world.”
—Sir Herbert Read (1893–1968)
“The slogan offers a counterweight to the general dispersion of thought by holding it fast to a single, utterly succinct and unforgettable expression, one which usually inspires men to immediate action. It abolishes reflection: the slogan does not argue, it asserts and commands.”
—Johan Huizinga (1872–1945)