Photodeposition of Diffraction Gratings in Glass

Abstract

Line patterns with spacings ranging from 10 to 50 μm have been achieved by 488 nm photolysis of porous glasses impregnated with Fe(CO)5. Photolysis was accomplished with a focused Ar+ laser impinging onto a sample mounted on a computer-controlled X-Y stage programmed to create a line pattern. The photodeposited grating was tested by generating a diffraction pattern with a He–Ne laser, which was then used to calculate the grating line spacings. The measured line spacings were found to be in excellent agreement with the spacings defined by the computer-driven stage. Consolidation of the porous glass occurs at 1200 °C, and decreases the sample volume as much as 35%. Line spacing decreases in direct proportion to the decrease in the dimension perpendicular to the grating lines of the sample and consolidation yields gratings that are capable of diffracting light, stable under a variety of conditions, and unaffected by high laser powers.