# Normalized frequency (fiber optics)

﻿
Normalized frequency (fiber optics)

In an optical fiber, the normalized frequency, V (also called the V number), is given by $V = {2 \pi a \over \lambda} \sqrt{{n_1}^2 - {n_2}^2}\quad = {2 \pi a \over \lambda} \mathrm{NA},$

where a is the core radius, λ is the wavelength in vacuum, n1 is the maximum refractive index of the core, n2 is the refractive index of the homogeneous cladding, and applying the usual definition of the numerical aperture NA.

In multimode operation of an optical fiber having a power-law refractive index profile, the approximate number of bound modes (the mode volume), is given by ${V^2 \over 2} \left( {g \over g + 2} \right)\quad,$

where g is the profile parameter, and V is the normalized frequency, which must be greater than 5 for the approximation to be valid.

For a step index fiber, the mode volume is given by 4V2/π2. For single-mode operation is required that V < 2.405, which is the first root of the Bessel function J0.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Normalized frequency — can refer to: Normalized frequency (digital signal processing) Normalized frequency (fiber optics), also known as V number This disambiguation page lists articles associated with the same title. If an …   Wikipedia

• Soliton (optics) — In optics, the term soliton is used to refer to any optical field that does not change during propagation because of a delicate balance between nonlinear and linear effects in the medium. There are two main kinds of solitons: spatial solitons:… …   Wikipedia

• Optical fiber — A bundle of optical fibers A TOSLINK fiber optic audio c …   Wikipedia

• Cutoff frequency — This article is about signal processing. For other uses, see Cutoff (disambiguation). Magnitude transfer function of a bandpass filter with lower 3 dB cutoff frequency f1 and upper 3dB cutoff frequency f2 …   Wikipedia

• Numerical aperture — The numerical aperture with respect to a point P depends on the half angle θ of the maximum cone of light that can enter or exit the lens. In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes… …   Wikipedia

• List of electronics topics — Alphabetization has been neglected in some parts of this article (the b section in particular). You can help by editing it. This is a list of communications, computers, electronic circuits, fiberoptics, microelectronics, medical electronics,… …   Wikipedia

• Mode volume — In fiber optics, mode volume is the number of bound modes that an optical fiber is capable of supporting. The mode volume M is approximately given by and , respectively for step index and power law index profile fibers, where g is the profile… …   Wikipedia

• Transmission line — This article is about the radio frequency transmission line. For the power transmission line, see electric power transmission. In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating… …   Wikipedia

• List of mathematics articles (F) — NOTOC F F₄ F algebra F coalgebra F distribution F divergence Fσ set F space F test F theory F. and M. Riesz theorem F1 Score Faà di Bruno s formula Face (geometry) Face configuration Face diagonal Facet (mathematics) Facetting… …   Wikipedia

• Coherent states in mathematical physics — Coherent states have been introduced in a physical context, first as quasi classical states in quantum mechanics, then as the backbone of quantum optics and they are described in that spirit in the article Coherent states (see also ). However …   Wikipedia