Miniature two-stage EDFA with broadband flat gain response

Dense WDM and other advanced lightwave systems require EDFAs (Er-doped fiber amplifiers) with broadband flat optical gain, low NF and reliable robust packaging. Different gain flattening techniques, such as using gain flattening filter and codoped fluoride fiber, have been investigated with limited achieved flat gain response. Low NF can improve system sensitivity and reduce detection power penalty. In this paper, a 2-stage double-pass EDFA with a gain flatness of /spl plusmn/0.2 dB over a 30 nm bandwidth and an NF of 4 dB in a small hermetically sealed compact package is reported.