| Title | Photo-induced gratings in thin color center layers on lithium fluoride. | | Author(s) | Bonfigli F, Vincenti MA, Almaviva S, Montereali RM, Nichelatti E, Nogueira RN, Kalinowski HJ | | Institution | Department of Physical Technologies and New Materials, ENEA, Frascati Research Center,via Enrico Fermi 45, 00044 Frascati (RM), Italy. | | Source | Appl Opt 2009 Nov 1; 48(31):G38-43. | | 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. | | Language | eng | | Pub Type(s) | Journal Article
| | PubMed ID | 19881643 |
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