Modeling high-power Er/sup 3+/-Yb/sup 3+/ codoped fiber lasers

High-power cladding-pumped Er/sup 3+/-Yb/sup 3+/ codoped fiber lasers (EYDFL) are analyzed with a detailed rate-equations model that takes into account the energy transfer between Yb/sup 3+/ and Er/sup 3+/. Examples of EYDFL with distributed Bragg reflector (DBR) mirrors at both fiber ends are demonstrated. Approximate quasi-analytical solutions to the rate equations show good agreement with the exact numerical solutions for practical operating conditions. An "optimum design" of the laser is discussed in relation to the fiber length that maximizes the output power.