1. Photo-induced gratings in thin color center layers on lithium fluoride
- Author
-
Bonfigli, Francesca, Vincenti, Maria Aurora, Almaviva, Salvatore, Montereali, Rosa Maria, Nichelatti, Enrico, Nogueira, Rogerio N., and Kalinowski, Hypolito Jose
- Subjects
Lithium compounds -- Optical properties ,Fluorine compounds -- Optical properties ,Diffraction gratings -- Observations ,Astronomy ,Physics - Abstract
We study the recording of permanent Bragg gratings on surface-colored lithium fluoride (LiF) crystals by using the interference pattern of a continuous-wave UV argon-ion laser operating at 244 nm. Gratings with spatial periodicity ranging from 400 to 1000 nm are written by using a phase-mask interferometer and are stable for several months after the writing process. Absorption and photoluminescence spectra show the bleaching of primary F and F -aggregate laser-active color centers as a result of the process. Confocal microscopy is used to determine the pitch and the profile of the fluorescent gratings. The UV laser-induced optical bleaching in highly colored LiF ultrathin layers is responsible for the periodic spatial modulation of absorption and photoemission properties that characterize the gratings. In the colored surface layer, a reduction of as much as 50% of the initial color-center-induced refractive-index increase has been estimated in the bleached areas. OCIS codes: 050.2770, 140.3380, 140.1700, 230.4000.
- Published
- 2009