Physical review. B, Condensed matter
Upconversion and migration in erbium-doped silica waveguides in the continuous-wave excitation switch-off regime
Sergey V. Sergeyev, Dmitry Khoptyar, B. Jaskorzyńska
Abstract
Based on an approach for averaging solution of rate equations over possible ensemble configurations, we derive integral equation for population inversion taking into account nonlinear homogeneous upconversion and migration in ${\mathrm{Er}}^{3+}$-doped silica waveguides for the case of 1480-nm CW excitation switch-off (CWES) regime. Because of pump for CWES is off, only migration tends to refill the holes in excitation distribution caused by upconversion. Thus the upconversion is weaker than that for the CW operation, except for $t=0$ and $\stackrel{\ensuremath{\rightarrow}}{t}\ensuremath{\infty},$ upconversion.