In all the infrared quantum counter systems reported to date, a single rare‐earth ion dopant was used as the activator. This limits the optimum concentration to about 1%, since above this value nonradiative processes begin to dominate. In order to increase the number of ions which can absorb the infrared signal Yb3+was used as a sensitizer. By making use of the energy transfer from Yb3+to Ho3+the green quantum counter fluorescence was increased by more than two orders of magnitude.