Periodic colour-centre structure formed under filamentation of mid-IR femtosecond laser radiation in a LiF crystalстатья
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Дата последнего поиска статьи во внешних источниках: 5 сентября 2016 г.
Аннотация:A colour-centre structure formed in a LiF crystal under
filamentation of a femtosecond mid-IR laser pulse with a power
slightly exceeding the critical power for self-focusing has been
experimentally and theoretically investigated. Strictly periodic
oscillations have been detected for the first time for the density of
the colour centres induced in an isotropic LiF crystal under filamentation
of a laser beam with a wavelength tuned in the range
from 2600 to 3350 nm. The structure period is found to be about 30
mm. With an increase in the laser radiation wavelength, the period
of the oscillations decreases and their amplitude increases. The
maximum colour centre density, observed under filamentation of a
3100-nm beam, is related to the increased contribution of the direct
generation of colour centres as a result of the absorption of an integer
number of photons by the exciton band. It is numerically shown
that the formation of a periodic colour-centre structure in LiF is
due to the periodic change in the light field amplitude in the light
bullet (1.5 optical periods long) formed under filamentation.