Patent ID: 9640938
Date: 2017-05-02
CPC Classifications: H01S,H04B,H04J,H04Q

Claim:
1. An optical amplifier comprising an optical path having an input end and an output end, a direction of propagation for an optical signal being defined which goes from the input end to the output end, a first erbium doped optical fiber placed along the optical path, a first gain flatting filter placed along the optical path downstream the first erbium doped optical fiber, a second erbium doped optical fiber placed along the optical path downstream the first gain flatting filter, a second gain flatting filter placed along the optical path downstream the second erbium doped optical fiber, a third erbium doped optical fiber placed along the optical path downstream the second gain flatting filter, and an optical pump optically coupled to the optical path so as to optically pump at least the first and the third erbium doped optical fiber, wherein each of the first and second pain flattening filters has a spectral loss curve having at a first wavelength comprised between 1555 nm and 1565 nm a first loss, at a second wavelength comprised between 1535 nm and 1545 nm a second loss and at a third wavelength comprised between 1575 nm and 1585 nm a third loss, and wherein the second loss of the first gain flattening filter is greater than, or equal to, −8 dB and the second loss of the second gain flattening filter is greater than, or equal to, −6 dB.