Color center photoluminescent nano-patterns induced in lithium fluoride by soft X-ray laser beam

We present the realization and characterization of photoluminescent nanometric periodic patterns of color centers (CCs) in lithium fluoride (LiF) produced by an interferometric method based on a coherent soft X-ray laser beam. Among broad-band light-emitting materials, LiF, in the form of crystals and thin films, is a radiation-sensitive material well known in dosimetry and as a laser-active medium in optically pumped photonic devices. Primary and aggregate electronic defects can be produced in LiF by low-penetrating electromagnetic radiation, like soft X-ray. The high brightness and spatial coherence of a capillary discharge laser, with the emission wavelength of 46.9 nm, allowed writing periodic lines of stable CCs at a nanometric scale emitting visible light under optical pumping. Interferometric encoding of luminescent nano-structures in LiF proved to be a powerful tool for producing low-dimensionality optical devices for photonic applications.