Laser recording of color voxels in lithium fluoride

Abstract

The problem of creating three different types of spatially selective voxels by laser radiation in the volume of an transparent optical medium was solved. Each of the created voxels provides one base color: red, green, or blue. Red and green voxels are microvolumes inside a crystal in which femtosecond laser pulses create luminescence centers that emit, respectively, in the red and green regions of the spectrum when illuminated with blue radiation that excites luminescence. Voxels responsible for the blue glow are microvolumes in which light scattering centers are created by femtosecond pulses. These voxels do not contain any luminescence centers; they scatter blue radiation, which excites the luminescence of red and green voxels. To solve the problem of creating spatially separated voxels of all three types in the volume of an optical carrier, we studied the temperature dependences of the spectra, the output, and the decay time constants of the luminescence of quantum systems created by femtosecond laser radiation. These dependences were studied during heating and cooling. The change in the voxel size of the three basic colors from the energy and the number of femtosecond pulses of a titanium-sapphire laser was studied. Irradiation regimes were found in which only luminescence centers are formed in voxels and scattering centers are not formed. On the basis of the results, a three-stage technology of laser irradiation and heat treatment of optical media was proposed and experimentally tested. This technology allows for creation of three-dimensional, full-color images, visualized under blue light.