Systems and methods to increase pump conversion efficiency of an optical fiber

A method for increasing optical pump conversion efficiency (PCE) for an optical fiber pumped by a multi-mode pump diode, the optical fiber including a first active region and a second active region, the first active region doped with erbium ions and the second active region doped with erbium ions and ytterbium ions, the optical fiber further including a cladding layer surrounding the core area, the method comprising:

• receiving, by the optical fiber, optical wavelengths from the multi-mode pump diode;
• absorbing, by the second active region, a spectrum of optical wavelengths;
• absorbing, by the first active region, optical wavelengths in a C-band;
• emitting, by both the first active region and the second active region, optical wavelengths in the L-band, via stimulated emission.

A system for amplifying an L-band signal, the system comprising:

• a source of multimode pumping light;
• a signal-pump combiner optically coupled to the source;
• and
• an optical fiber optically coupled to the source and signal-pump combiner, the optical fiber including a first active region and a second active region, the first active region doped with erbium ions and the second active region doped with erbium ions and ytterbium ions, the optical fiber further including a cladding layer surrounding the core area.