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Two‐Photon Absorption via Deep Local Levels as Virtual Intermediate States in Semiconductors
Author(s) -
Baltramiejūnas R.,
Gavryushin V.,
Račiukaitis G.,
Kubertavičus V.,
Kazlauskas A.
Publication year - 1989
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221510233
Subject(s) - absorption (acoustics) , semiconductor , momentum (technical analysis) , photon , two photon absorption , atomic physics , range (aeronautics) , impurity , physics , condensed matter physics , materials science , chemistry , optoelectronics , optics , quantum mechanics , laser , finance , economics , composite material
The enhancement of the coherent nonlinear losses are observed in ZnO and ZnSe crystals within the whole range of the interband two‐photon absorption (TPA) spectra. The effect is explained theoretically in terms of nonresonant participation of the deep local levels (DL) of impurities and native defects in the forbidden gap as additional intermediate virtual states of TPA. Calculations of interband TPA via DL including the influence of the momentum indeterminacy in local states are presented. The role of spatial interference of virtual contributions of the localized intermediate states in the momentum conservation is revealed. The possibility of the technological control of the additional nonlinearities is shown experimentally. The place of these phenomena among the widely investigated processes of coherent TPA via band states and the incoherent two‐step absorption through DL are discussed.