Holographic writing of volume-type microgratings in silica glass by a single chirped laser pulse

Refractive-index-modulated volume-type gratings were holographically encoded inside pure ${\mathrm{SiO}}_2$ glass plates by a single chirped (0.5–5 ps duration) laser pulse generated from a mode-locked Ti:sapphire laser (wavelength ∼800 nm, emission pulse duration ∼100 fs). Scanning-electron- and confocal-optical-microscopic observations revealed that microgratings were formed inside the sample at a depth of ∼5 mm from the top surface. Also, inside the ${\mathrm{SiO}}_2$ glass, three-dimensional periodic arrays of the grating and crossed-grating structures were fabricated. The present technique is a fast method that is applicable not only for encoding volume-type gratings inside all nonphotosensitive transparent dielectric materials, but also for fabricating optical devices such as distributed-feedback lasers and multilayered memories.