Editing Effective mode volume (section)

 {{See also|Mode volume}}

For an [[optical fiber]], the '''effective mode volume''' is the square of the product of the diameter of the [[Near and far field|near-field]] pattern and the sine of the [[radiation angle]] of the [[Near and far field|far-field]] pattern. The diameter of the near-field [[radiation pattern]] is defined here as the [[full width at half maximum]] and the radiation angle at half maximum [[radiant intensity]]. Effective [[Transverse mode|mode]] volume is [[Proportionality (mathematics)|proportional]] to the breadth of the relative distribution of [[Power (physics)|power]] amongst the modes in a multimode fiber. It is not truly a spatial volume but rather an ''"optical volume"'' equal to the product of area and solid angle. The power divided by the effective mode volume is proportional to the [[radiance]] of the light emitted by the fiber.