Formation of luminescent emitters by intense laser radiation in transparent media

Abstract

The formation of luminescent colour centres in the LiF crystal under the action of femtosecond pulses of the first harmonic of a Ti : sapphire laser is experimentally studied. The experiments were carried out at low-and high-aperture focusing of radiation. The effect of both single pulses and multi-pulse trains on the crystals was studied. Channelling of laser radiation in the waveguides, induced by the filaments of the first pulses, is found. The multiphoton mechanism of interband absorption is confirmed. The optimal conditions of laser impact for designing luminescent emitters in the LiF crystal are determined. .ru; A.V. Kirpichnikov, E.V. Pestryakov, S.N. Bagayev Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, prosp. Akad. Lavrent'eva 13/3,

The accumulation of femtosecond laser radiation energy in crystals of lithium fluoride

“…The photon energy corresponding to the radiation of a femtosecond titanium-sapphire laser with λ=800 nm is ~ 1.5 eV. Therefore the formation of color centers in the crystals under study is due to multiphoton absorption of laser radiation energy by the electronic subsystem of matter with the formation of electron-hole pairs as a result of self-focusing and filamentation of the exciting femtosecond laser radiation [7]. The mechanism of the color centers creation under the influence of femtosecond laser radiation includes highly nonlinear generation of electron-hole pairs in the region of passage of the filaments, their recombination resulting with the formationif anionic excitons, decay of the excitons into the Frenkel defects by the Lushchik-Vitola-Hershey-Puli mechanism, their recharge, migration and aggregation.…”

“…It is known that luminescent defects are effectively created by intense femtosecond pulses during the irradiation of dielectric crystals, predominantly with excitonic mechanism of defect formation [1][2]. Defects induced by femtosecond laser pulses in such crystals are simple and aggregate color centers, characteristic for radiation staining [4][5].…”

Метод Лазерной Колорации В Экспериментах По Филаментации Одиночных Импульсов И Образованию Световых Пуль В Однородных Прозрачных Диэлектриках

“…Уникальной особенностью этих ЦО в LiF, обнаруженной при воздействии фемтосекундными лазерными импульсами [12], является их столь интенсивная люминесценция, что состоящие из них долгоживущие микроструктуры, созданные при филаментации всего одного лазерного импульса, могут быть легко зарегистрированы и исследованы при последующей подсветке в полосе их поглощения вблизи 450 nm непрерывным лазером. Это было продемонстрировано в [13], где исследовалась возможность создания люминесцирующих наноэмиттеров при множественной филаментации фемтосекундного единичного лазерного импульса на 800 nm с пиковой мощностью, на три порядка превышающей критическую мощность самофокусировки для LiF. LiF имеет высокую термическую и оптическую стабильность ЦО при комнатной температуре, что позволяет исследовать структуры из ЦО различными методами после их записи.…”

Multiple filamentation of femtosecond laser pulses

“…At the same time, experimental investigations of fila mentation in air are complicated by a number of accompanying factors: the heterogeneity and the non stationary character of the media; the great spatial extent of the plasma channel; and the need to use fairly high power pulses because of the low critical power of self focusing, compared to liquid and solid media. In [4,5], it was shown that the use of alkali-halide crys tals as nonlinear fluorescent photosensitive media allows experimental registration of the spatial patterns of the multiple filamentation of relatively low power pulses in small samples, due to the formation of fluo rescent color centers in regions of the material ionized with laser radiation [4,5]. The high spatial resolution of three dimensional shots of filamentation allows detailed comparison with modeling results.…”