- Since the core and cladding have different indices of refraction hence they have different attenuation coefficients α1 and α2
- For step index fiber, the loss for a mode order (v, m) is given by,
For low-order modes, the expression reduced to
where, and are fractional powers.
- For graded index fiber, loss at radial distance is expressed as,
The loss for a given mode is expressed by,
where, P(r) is power density of that model at radial distance r.