Influence of Cr3+ doping on the enhanced dielectric and nonlinear optical features of pyroelectric Pb5Ge3O11 single crystals

摘要: Abstract It was shown a possibility to enhance the output laser stimulated second harmonic susceptibility for Pb 5 Ge 3 O 11 single crystals in their ferroelectric phase using an external light and appropriate doping by Cr 3+ ions. The improvement of Nonlinear Optical effect is achieved due local enhancement charge density non-centrosymmetry (acentricity), changes effective excitation occupied states additional photo-polarization 3d-localized states. addition ions leads hyperpolarizability. To clarify origin observed effect, understand its interesting properties, calculations band structure were performed using, first time, first-principles DFT calculations. These reveal that has indirect energy gap E g equal about 2.6 eV highest valence very flat separated from remaining bands small 0.3–0.4 eV. This discovery could explain many unexplained puzzling experimental results especially different photo-activated effects found previously . possible calculated discussed. order optical explained within framework charges particular dopants during coherent illumination.