Avalanche-like up-conversion at nonlinear coupling of pumping channels: effect of ions concentration

We report results on avalanche-like effect in up-conversion on Er ions-doped in KGW crystal for concentrations of 1 and 10−4 wt.%. Our experimental and theoretical data point to the conclusion, that avalanche-like behavior observed earlier at low trace concentrations [1] occurs also at much larger concentrations (up to 1%).