The Luminescence Control And Valence State Conversion Of Rare-earth Ions Under Femtosecond Laser Field

Rare earth ions find wide applications in laser sources,fiber communication,bio-imaging and bio-labeling due to their excellent optical properties,like good color stability,high energy conversion efficiency,narrow spectral lines etc.They can also be used in developing ultrahigh density optical memories and new optical devices by taking advantage of their valence state conversion.Featuring ultra-high peak intensity,ultra-short pulse duration and broad spectral bandwidth,femtosecond laser pulses are ideal sources for exciting the up-conversion luminescence?UCL?and valence state conversion of doping rare earth ions.This thesis is dedicated to the study of manipulating the up-conversion luminescence and valence state conversion of doping rare earth ions under the irradiation of femtosecond laser fields.The main contents are as follows.?1?We have carried out experimental study on controlling the UCL in the Sm³⁺doped NaYF₄ glass sample by phase shaping the 800nm femtosecond excitation laser pulses.Both enhancement and suppression of the UCL have been realized by optimizing the spectral phases of the excitation laser with a home-built program based on self-adaptive feedback.A resonance-mediated three photon excitation model has also been proposed and explained the experimental observations well.?2?We have experimentally investigated the valence state conversion of Eu³⁺?Eu²⁺in the glass sample of 0.5EuF₃-52ZrF₄-20BaF₂-4.5LaF₃-3AlF₃-20NaF under the irradiation of focused 800nm femtosecond laser pulses.The triple frequency of the same laser has also been generated via BBO crystals and used to probe the occurence of photo-induced valence state conversion from Eu³⁺?Eu²⁺.