Efficiency optimization of high-power, Er^3+–Yb^3+-codoped fiber amplifiers for wavelength-division-multiplexing applications

Abstract

A rate-equations model that takes into account the energy transfer between Er3+ and Yb3+, as well as Er3+ clustering, is employed to analyze the power conversion efficiency (PCE) of high-power, gain-flattened, Er3+–Yb3+-codoped fiber amplifiers (EYDFA). Numerical results for C-band EYDFA and L-band EYDFA show that the PCE strongly depends on the excess pump losses and on the pump-band amplified spontaneous emission (ASE). It is found that the L-band EYDFA is more efficient in the limit of strong injected signal powers and large cladding areas. It is also shown that the PCE significantly improves on increasing the Yb3+ concentration in the C-band EYDFA, whereas in the L-band EYDFA it mainly depends on the pump wavelength. The effect of Er3+ clusters on the PCE is discussed.