Application of Z-scan technique for the study of nonlinear absorption in chemically reduced LiNbO3 crystals

5th International Conference New Achievements in Materials and Environmental Science

材料科学;生态环境科学

Kostritskii, S.M.^1 ; Aillerie, M.^2,3 ; Kokonyan, E.^4,5 ; Sevostyanov, O.G.^6

RPC Optolink, Sosnovaya al. 6, Zelenograd, Moscow

124489, Russia^1

Université de Lorraine, LMOPS, EA 4423, Metz

57070, France^2

Centrale Supélec, LMOPS, Metz

57070, France^3

Armenian State Pedagogical University, Tigran Mets Ave., 17, Yerevan, Armenia^4

Institute for Physical Researches, National Academy of Sciences of Armenia, Ashtarak-2, Armenia^5

Phys. Dept., Kemerovo State University, Krasnaya str. 6, Kemerovo

650043, Russia^6

关键词: Bound polaron;    Intensity dependence;    LiNbO3 crystals;    Nonlinear absorptions;    Nonlinear optical absorption;    Small polarons;    Z-scan experiment;    Z-scan technique;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/879/1/012003/pdf
DOI  :  10.1088/1742-6596/879/1/012003

来源: IOP

【 摘 要 】

The nonlinear absorption (NLA) was studied by open-aperture Z-scan experiments in the chemically reduced nominally pure LiNbO3crystals at cw-illumination with the red (644 nm) and green (514.5 nm) laser beams. The magnitude of the measured NLA is considerably different from the reported Z-scan results obtained in as-grown LiNbO3. The positive sign of NLA obtained with the red light has been related to the generation of the small bound polarons absorbing in red and near-IR ranges. Application of green light results in the light-induced transparency, i.e. the Z-scan traces show negative sign of NLA. Intensity dependence of Z-scan traces allows for conclusion that the photo-induced dissociation of small NbLi4+:NbNb4+bipolarons and sequent generation of small polarons gives the dominating contribution to the nonlinear optical absorption in reduced crystals with a large bipolarons concentration.