Fabrication of Microholographic Gratings on Al2O3 Grown by Atomic Layer Deposition Using a Femtosecond Laser

Microholographic gratings were prepared on an aluminum oxide ($Al_2O_3$) surface using a 140-fs pulse at a center wavelength of 800 nm. The $Al_2O_3$ was deposited on a silicon wafer and on indium tin oxide glass to a thickness of approximately 25 nm using an atomic layer deposition process. The silicon wafer substrate exhibited reflection-type gratings that were measured as a function of the incidence angle. The diffraction efficiency of the fabricated gratings was measured, with a maximum diffraction efficiency of 45% at an incidence angle of approximately $30^{\circ}$.