Fabrication of Sub-Micron Surface Relief Gratings on the Azo-Polymer Films by a Low Zero-Order Diffraction Phase Mask

Azo-polymer materials had a large photoinduced refractive index and surface relief change. A sub-micron surface relief grating was fabricated directly by the irradiation of a UV pulse laser using a low zero-order diffraction phase mask. The effect of the zero-order diffraction of the phase mask was investigated. It suggested that the grating pattern formed by using the phase mask depended on the exposure time. Experimental results agree well with the theoretical analysis.