<P> l (\ displaystyle l \, \!) is the length of the fiber taken for observing the pulse dispersion, </P> <P> c ≈ 3 × 10 8 m / s (\ displaystyle c \ approx 3 \ times 10 ^ (8) ~ \ mathrm (m / s) \, \!) is the speed of light, and </P> <P> k (\ displaystyle k \, \!) is the constant of graded index profile . </P>

Advantages of graded index fiber over step index fiber