Independent control of EDFA gain shape and magnitude using excited-state trapping

Controlled use of excited-states of erbium are used to decouple the magnitude and shape of the gain spectrum of an erbium-doped fiber amplifier (EDFA) containing a low phonon energy glass. This makes it possible to operate a single EDFA at multiple gains without the gain flatness degradation referred to as dynamic gain-tilt. Dynamic gain-tilt free operation is demonstrated in the long-wavelength portion of the erbium gain spectrum using an erbium-doped ZBLAN fiber.