Abstract:
This paper reports on a study of the kinetics of electron tunneling transport between electron and hole centers in Li$_2$B$_4$O$_7$ and LiB$_3$O$_5$ lithium borate crystals under the conditions where the mobility of one of the partners in the recombination process is thermally stimulated. A mathematical model has been proposed to describe all specific features in the relaxation kinetics of the induced optical density observed in Li$_2$B$_4$O$_7$ (LTB) and LiB$_3$O$_5$ (LBO) nonlinear optical crystals within a broad time interval of 10$^{-8}$–1 s after a radiation pulse. The results of calculations have been compared with experimental data on transient optical absorption (TOA) of LTB and LBO crystals in the visible and ultraviolet spectral regions. The nature of the radiation defects responsible for TOA and the dependence of the TOA decay kinetics on temperature, excitation power, and other experimental conditions have been discussed.