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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 example, the higher dispersion flint glasses have relatively small Abbe numbers < whereas the lower dispersion crown glasses have larger Abbe numbers. Values of V d {\displaystyle V_{\mathsf {d}}} range from below 25 for very dense flint glasses, around 34 for polycarbonate plastics, up to 65 for common crown glasses, and 75 to 85 for some ...
In a dispersive prism, material dispersion (a wavelength-dependent refractive index) causes different colors to refract at different angles, splitting white light into a spectrum. A compact fluorescent lamp seen through an Amici prism. Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. [1]
A. R. Forouhi and I. Bloomer deduced dispersion equations for the refractive index, n, and extinction coefficient, k, which were published in 1986 [1] and 1988. [2] The 1986 publication relates to amorphous materials, while the 1988 publication relates to crystalline.
where ϕ(r, t) is the density of the diffusing material at location r and time t and D(ϕ, r) is the collective diffusion coefficient for density ϕ at location r; and ∇ represents the vector differential operator del. If the diffusion coefficient depends on the density then the equation is nonlinear, otherwise it is linear.
The boundary side coefficient is set to zero (cutting the link with the boundary) and the flux crossing this boundary is introduced as a source which is appended to any existing and terms. Subsequently the resulting set of equations is solved to obtain the two dimensional distribution of the property φ {\displaystyle \varphi {}}
Dispersion can be differentiated from diffusion in that it is caused by non-ideal flow patterns [1] (i.e. deviations from plug flow) and is a macroscopic phenomenon, whereas diffusion is caused by random molecular motions (i.e. Brownian motion) and is a microscopic phenomenon.
It is defined as the ratio of the convection current to the dispersion current. The Bodenstein number is an element of the dispersion model of residence times and is therefore also called the dimensionless dispersion coefficient. [1] Mathematically, two idealized extreme cases exist for the Bodenstein number.