The experimental evidence of the amplified spontaneous emission of Yb3+ ions in LiYbF4 crystal

The experimental evidence of the amplified spontaneous emission of Yb3+ ions in LiYbF4 crystal, which partially stipulates up-conversion processes in Yb-sensitized phosphors, doped by rare-earth ions are presented for the first time. To do that the spatial distributions and the spectra of Yb3+ ions luminescence along the excitation radiation propagation through the sample were studied simultaneously. The laser diode radiation (1 W, λ=932 nm) was used for the luminescence excitation and its surface power density was varied by shifting of the position of the laser beam waist within the sample (similar to Z-scanning).