Modeling and optimization of short Er3+-Yb3+ codoped fiber lasers

A theoretical study of short Er³⁺- Yb³⁺ codoped fiber lasers (EYDFLs) is presented. Examples include centimeter-length EYDFLs pumped at 978 nm, with distributed Bragg reflector (DBR) mirrors at both fiber ends. Approximate quasi-analytical solutions are shown to be in excellent agreement with the exact numerical solution of the rate equations. Using the quasi-analytical model, we demonstrate a design optimization of a short EYDFL. The effects of the Yb³⁺ concentration, laser wavelength, output mirror reflectivity, and pump wavelength are considered and discussed with relation to the optimal laser length and output efficiency.