Waveguide dispersion is chromatic dispersion which arises from waveguide effects: the dispersive phase shifts for a wave in a waveguide differ from those which the wave would experience in a homogeneous medium. The total dispersion is the combination of material dispersion and waveguide dispersion. It is usually calculated (for a given propagation mode) from the frequency dependence of β, the imaginary part of the so-called propagation constant, which is the overall phase shift per unit length which the guided wave experiences. For calculating the required β values, one usually requires a mode solver.
The origin of waveguide dispersion can be understood by considering that a guided wave has a frequency-dependent distribution of wave vectors (k vectors), whereas a plane wave (as the reference case) has only a single wave vector, which points exactly in the propagation direction.
Waveguide dispersion is important in waveguides with small effective mode areas. Examples are optical fibers, in particular certain photonic crystal fibers, but also other single-mode fibers as used in, e.g., optical fiber communications. Waveguide dispersion may be tailored via the fiber design to obtain the desired dispersion properties; see e.g. the article on dispersion-shifted fibers. For fibers with large mode areas, waveguide dispersion is normally negligible, and material dispersion is dominant.
|||J. A. Mores Jr et al., “Efficient calculation of higher-order optical waveguide dispersion”, Opt. Express 18 (19), 19522 (2010), doi:10.1364/OE.18.019522|
|||A. W. Snyder and J. D. Love, Optical Waveguide Theory, Chapman and Hall, London (1983)|
|||R. Paschotta, tutorial on "Passive Fiber Optics", Part 10: Chromatic Dispersion|