Optical applications of laser-induced gratings in Eu doped glasses

Laser-induced changes in the refractive index are used to create superimposed transient population gratings and permanent structural gratings in Eu(3+) doped silicate and phosphate glasses. Potential uses for these laser-induced gratings (LIGs) are investigated. First, the structural gratings are shown to be permanent at room temperature and their use as a holographic storage medium is discussed. Second, a permanent LIG of this type is used to demultiplex multifrequency laser beams, demonstrating its use as a tunable line filter. Third, the transient LIG is used to modulate the amplitude of a laser beam which is passed through the sample and scatters off the permanent LIG. This results in information being transferred from one beam to another beam. It was found that thermal lensing plays an important role in the formation of this type of permanent LIG and a procedure for determining the tilt angle of the fringes of the LIG is discussed.