Optical properties of lithium fluoride fibers grown by micro-pulling-down method

摘要

Fluoride single-crystalline fibers were grown by the micro-pulling-down (μ-PD) technique. The optical properties of the LiF fiber and the bulk crystal (grown by Czochralski technique) were compared. Both samples were irradiated with 40 M rad of gamma rays at room temperature and color centers were successfully produced. The emission spectra of the fiber and the bulk crystal when excited at 447 nm show the typical broad emission bands related to the F_3~+ and F_2 centers, with peaks at 535 and 650 nm, respectively. Both spectra contain a very strong emission band centered at 1120 nm with the same half width of 1350 cm~(-1) when excited with a InGaAs diode laser at 968 nm. These results indicate a potential use of these new LiF fibers in miniaturized active optical devices.