Fabrication of Diffractive Optical Elements in Polymers by 400-nm Femtosecond Laser Pulses

This report describes fabrication of volume gratings inside various matrix polymers using femtosecond laser irradiation at a wavelength of 400 nm.We investigated the diffraction efficiencies of volume gratings with a period of 10 μm by focusing 400-nm laser pulses with a 0.1-numerical aperture objective lens.We compared the polymers' diffraction efficiencies at 400 nm and 800 nm.The largest refractive index change was induced in polymers with low density.The large refractive index change was attributed to its volume contraction based on its low density.