Mode field diameter calculator

Input

Output

μm

About this calculator

This calculator computes the mode-field diameter of the fundamental mode in a step-index fiber using Marcuse's equation:

MFD=2a(0.65+1.619V3/2+2.879V6)MFD = 2a\left(0.65 + \dfrac{1.619}{V^{3/2}} + \dfrac{2.879}{V^6}\right)

where VV is the normalized frequency

V=2πλaNAV = \dfrac{2\pi}{\lambda}a\mathrm{NA}
and λ\lambda is the signal wavelength, aa is the fiber core radius and NA\mathrm{NA} is the core numerical aperture.