Direct formation of a surface-relief grating on glass by ultraviolet visible laser irradiation

Surface-relief gratings were directly fabricated onto a glass surface by UV-visible laser irradiation. The glass surface was pretreated by molten salt, including Ag ions. Periodic intensity modulation of the laser light was conducted with a phase mask or by an interference technique. A pattern generated by intensity modulation was precisely transcribed onto the glass surface and a surface-relief grating was formed. The period and depth of the grating were 0.5 to 10 microm and less than 0.8 microm, respectively. The cross-sectional profile of the grating was sinusoidal or triangular, with very smooth surface morphology.