Design and fabrication of constant-pitch circular surface-relief diffraction gratings on disperse red 1 glass

Circular surface-relief diffraction gratings with a constant pitch were photo-inscribed on thin films of a disperse red 1 functionalized glass-forming compound using a novel holographic technique. Various light-interfering metallic fixtures, which consisted of annular rings with a sloped and polished inner surface, were designed and fabricated. Each of them allowed the inscription of stable and high-quality circular diffraction gratings with pitches ranging from approximately 600-1400 nm and depths up to 250 nm. This was accomplished by exposure to a collimated laser beam with an irradiance of 604  mW/cm2 for 350 s. The resulting gratings had a diameter of 11.4 mm and had the advantage of being produced in a simple single-step procedure with no postprocessing or specialized equipment. The pitch and diameter of these circular gratings were dependent on the fixture geometry, while the depth was related to the exposure time.