Simultaneous fabrication of laser-active colour centres and permanent microgratings in lithium fluoride by a single femtosecond pulse

Abstract

We report, for the first time, simultaneous fabrication of laser-active F2 and F3+ colour centres in lithium fluoride and permanent periodic gratings with fringe spacings as fine as sub-micron size by two interfering infrared femtosecond (fs) laser pulses. In particular, the optical properties (absorption and luminescence) of F2 and F3+ colour centres produced by a single fs laser pulse are compared with those created by damage from radiation such as x-rays. The present technique of simultaneously fabricating laser-active colour centres and functional fine-periodic structures in photo-insensitive transparent materials may well be a useful method for making miniaturized optical devices.

Distributed‐feedback color center lasers in wide‐band gap materials fabricated by a pair of chirped femtosecond pulses

“…The slope efficiency with respect to pump energy was ~10 %. Moreover, the refractive index change induced by the color centers fabricated by fs laser pulses was assessed to be about ~1% [6], therefore a lasing beam is efficiently confined to its one-dimensional active channel waveguide. As already reported [2,3] that the F 2 centers in LiF are not stable under high pumping intensities at RT, compared to a defect-stabilized (F 2 + )** center and F 2 -center.…”

“…In a recent paper, with femtosecond (fs) laser pulses we reported, for the first time to our knowledge, simultaneous fabrication [6] of laser-active color centers and fine-pitched micro-grating structures in bulk LiF. Moreover, we demonstrated the first realization [7] of a pulsed DFB color center laser in LiF containing F 2 centers at RT.…”

Permanent bleaching of F2 color centers in lithium fluoride under UV light illumination

“…2 to 8.38×10 4 Gy. An accurate comparison between optical absorption, photoluminescence and photo-excitation measurements, performed before and after laser irradiation, revealed a selective change in the CCs concentrations: a permanent bleaching of F 2 CCs was observed in all the investigated crystals and a critical dependence from the used power density has been highlighted.…”

“…In the last decades a great interest was devoted to propose [2] and investigate different irradiation methods and techniques for the development of miniaturised light emitting devices based on this interesting material [3]. Recently F 2 laser emission in the red was claimed in x-ray irradiated LiF crystals, combining Bragg gratings and waveguides induced by ultra-short infrared laser pulses [4]. We studied the possibility to use a continuous wave (CW), frequency doubled, Ar ion laser operating at the wavelength of 244 nm, which is coincident with the absorption peak of the F band [5], to modify the concentrations of F 2 and F 3 + laser active CCs in LiF crystals colored by gamma rays.…”

Luminescent nanostructures based on colour centres produced in LiF films by direct writing with an X‐ray microprobe

“…In Lithium Fluoride (LiF) they present very interesting optical properties exploited for the realisation of laser and amplifiers [2,3] operating at room temperature (RT) in the visible and near infrared spectral range. As a matter of fact, several photonic devices have been demonstrated in LiF crystals coloured with different kinds of radiation, like evanescent field amplifiers [4], optical waveguides [5] and distributed feedback (DFB) lasers [6]. Recently LiF films treated by low energy electrons have been successfully exploited for the realisation of miniaturised active devices [7], like optical microcavities and point-light sources.…”