Based on Raman and hyper-Raman scattering experiments and on direct green light absorption measurements, excitations of a new type - charge transfer excitons - are found to exist in Ge-doped silica fibers, whose self-organization (orientation ordering of dipole moments) leads to positive feed-back in response to a static electric field. An electric field of 10~5 V/cm then results breaking the inversion symmetry of the initially centrally symmetric medium and allowing the second harmonic to be generated. Generation persists only at the medium preparation stage and self-switches off upon a transition to the stationary state.
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机译：根据拉曼和超拉曼散射实验以及直接的绿光吸收测量，发现掺锗的石英纤维中存在一种新型的激发态-电荷转移激子，其自组织（偶极矩的取向顺序）导致响应静电电场而产生正反馈。然后，产生10〜5 V / cm的电场会破坏最初的中心对称介质的反对称性，并产生二次谐波。生成仅在介质准备阶段持续存在，并在过渡到静止状态时自动关闭。
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