The effect of In3+ doping on the optical characteristics of Ho:LiNbO3 crystals

A series of Ho:LiNbO3 crystals doped with x mol% In3+ ions (x = 0, 1, 3 and 5 mol%) were grown by the conventional Czochralski technique. Up-conversion emission spectra was observed under 808 nm femtosecond laser excitation in the In3+ doped Ho:LiNbO3 crystals at room temperature. The experimental results indicate that blue, green, violet and red up-conversion emission can be obtained from In3+ doped Ho:LiNbO3 crystals. From the pump energy dependence investigation, it is known that the up-conversion mechanism is the two-photon process. The light-induced scattering was investigated as a function of exposure energy. The effect of In3+ on the optical characteristics of Ho3+ in LiNbO3 crystal was investigated and concluded, and is reported here. The surface the as-prepared In3+ doped Ho:LiNbO3 is very smooth and practically free of droplets as highlighted by atomic force microscopy (AFM). The root-mean-square (rms) surface roughness of the sample was determined to be 11.573 nm.