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## Homework Statement

One of the most exciting developments in lightwave engineering is the Erbidium doped fiber amplifier (ERDF A). It is very quiet(low noise) has a bandwidth of hundreds of GHz and relatively low cost.The fiber is "pumped" by a semiconductor laser operating at 850nm and the light carrying the information at 1550nm is amplified. The 'attenuation'

constant is given as u=-0.046m^-1. If I have 0.01mW entering the ERDFA

and I would like to get 100mW out, how long should be my fiber amplifier?

If the efficiency of the amplifier is 20% how much pumping power do I

need?

## Homework Equations

Loss Equation e^(-2*α(z1-z0)

alpha is attenuation constant

if the negative sign was removed. would this be a gain equation?

## The Attempt at a Solution

I do not know where to start, the teacher said the wavelengths were irreverent.