Abstract
Laser emission from a 1.5‐μm wavelength InGaAsP/InP diode was shown to be efficiently converted to visible or to near‐infrared light by Er‐containing infrared‐excitable phosphors. The visible emission has been markedly enhanced in Yb‐sensitized phosphors under 0.97‐μm wavelength auxiliary light irradiation especially under weak 1.5‐μm wavelength excitation. The enhancement mechanism has proved to be Yb‐sensitized quantum counter action.