Numerical analysis of Yb3+-sensitised, Er3+-doped, fibre-ring laser

The performance of a Yb3+-sensitised Er3+-doped, continuous-wave, fibre-ring laser is analysed using a comprehensive numerical model. The model is based on iterative solution of propagation-rate equations and takes into account realistic refractive-index profile and Er3+/Yb3+-doping distribution function, uniform upconversion from the I-4(13/2) erbium level and propagation of amplified spontaneous emission in the pump wavelength range. The dependence of output power on active fibre length, input pump power and output coupling ratio has been investigated. The analysis has shown that the laser can be tuned in the range 1525nm - 1610nm. The calculated ring-laser characteristics have been found in quantitative agreement with the experimentally obtained data.