Color center conversion by femtosecond pulse laser irradiation in LiF:F_2 crystals

Abstract

We report the observation of intense spontaneous emission of green light from LiF:F(2):F(3) (+) centers in active channel waveguides generated in lithium fluoride crystals by near-infrared femtosecond laser radiation. While irradiating the crystal at room temperature with 405 nm light from a laser diode, yellow and green emission was seen by the naked eye. Stripe waveguides were fabricated by translating the crystal along the irradiated laser pulse, and their guiding properties and fluorescence spectra at 540 nm demonstrated. This single-step process inducing a waveguide structure offers a good prospect for the development of a waveguide laser in bulk LiF crystals.

Photoluminescence of Neutron-Irradiated LiF Single Crystals

“…The ultra-short high intensity laser pulses can produce a great number of F-centers in LiF single crystals that would give rise to the F 2 , F 3 , F 2 + , F 3 + aggregates [10,11]. After exciting a non-radiated LiF crystal with an argon laser (λ = 458 nm) no luminescence was revealed; consequently, in our case no color centers were produced.…”

“…The luminescence peak at ~ 680 nm could arise due to the luminescence of F 2 centers, while that at 630 nm -due to the F 3 + (two electrons bound to three neighboring anion vacancies) center luminescence [10,11,12]. The origin of the rest of the peaks is not yet clear.…”

Recombination gamma-luminescence at the nanometal Li – dielectric LiF interfaces

“…Lately LiF was used for luminescent microscope imaging and soft X-ray imaging detectors at submicron resolution (Baldacchini, 2002;Baldacchini et al, 2005). Intensive spontaneous green photoemission was observed in LiF doped with F 2 and F 3 þ centers in the active channel waveguides created under irradiation with near IR femtosecond laser pulses by means of 2-photon absorption (Cheng et al, 2007). At exposure of LiF:(F, F 2 , F 3 , V k ) crystals to 20 ns pulses of 200 keV electrons at 80-300 K there occurred radioluminescence at the band 910 nm (F 2 þ ), which grew above 140 K due to delocalization of V k centers (thermalized H-centers), and 530 nm (F 3 þ ), which decreased with the fluency growth to 10 11 cm À 2 and was independent on temperature (Lisitsina, 2001 (Lisitsina et al, 2013).…”

Features of propagation of the high-intensity femtosecond laser pulses in magnesium and sodium fluoride crystals

“…Femtosecond laser-treated alkali and alkaline earth fluorides find promising application as information storage media, optical waveguides, gratings, and other micro and nanostructures [4][5][6][7].…”