, the term normalized frequency
) has the following meanings:
1. In an optical fiber, a dimensionless quantity, V , given by the following equation, where a is the core radius, λ is the wavelength in vacuum, n1 is the maximum refractive index of the core, and n2 is the refractive index of the homogeneous cladding:
- Note 1: In multimode operation of an optical fiber having a power-law refractive index profile, the approximate number of bound modes (i.e the mode volume), is given by the following equation, where V is the normalized frequency greater than 5 and g is the profile parameter.
- Note 2: For a step index fiber, the mode volume is given by V2/2. For single-mode operation, V < 2.405. Synonym: V number.
between an actual frequency
and a reference value.
3. The ratio between an actual frequency and its nominal value.
Source: from Federal Standard 1037C and from MIL-STD-188