Frequency upconversion in Tm- and Yb:Tm-doped silica fibers

Frequency upconversion has been observed and studied in Tm3+-doped and Yb3+-sensitized Tm3+-doped silica fibers. In the singly singly doped fiber upconversion to the blue and UV has been observed under excitation in the red (660 nm) and infra-red (1.064µm). In the co-doped fiber upconversion has also been observed under excitation at around 800-900 nm