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Definition: a parameter determining the phase delay per unit length for propagation in a waveguide
In a waveguide structure such as an optical fiber, the guided light experiences a phase delay along the propagation direction which depends on both the refractive index of the core and the cladding material. The effective phase change per unit length is described by the wavenumber β, which can be expressed by
where neff is the effective refractive index. As the latter depends on the propagating mode, it is also called the modal index or modal refractive index.
See also: refractive index, waveguides, fibers, wavenumber
Category: fibers and other waveguides
