Researches On The Fabrication And Diffraction Properties Of Polymer Grating

Grating is a kind of optical element of optical research, which is important and has been widely used in optical measurement, optical information processing, optical sensing, optical communication, optical interconnection, and other fields. Due to the effects of external environment, such as temperature, humidity and electromagnetic and so on, the grating structure will be changed easily, and it’s performance will be unstable and even reduced in the work. On the one hand, in order to make the grating element or the devices of containing a grating element have stronger adaptability to the environment, expand its application scope and improve their work performance, and on the other hand, due to polymer materials having high heat-electric coupling coefficient, low dielectric constant, small quality, more simple production process, low cost, easy synthesis and modification, and other advantages, polymer grating has become a hot research topic. In this paper, polymer optical materials such as SU-8 and PDMS are used to fabrication gratings. These two kinds of gratings will show different diffractive properties. The diffraction properties are investigated theoretically and experimentally in this paper.Firstly, this paper introduces the structure and the characteristic of diffraction grating. The resonant guided mode of sub-wavelength grating is also described. The fabrication technology including digital mask lithography methods for diffraction grating at home and abroad are discussed.Then, the polymer plane binary grating whose period is modulated with different refractive index values is proposed. The scalar diffraction theory is used to analyze the diffractive properties of the polymer plane binary phase gratings, and rigorous coupled wave analysis method is used to analyze the guided mode resonance of the single- and double-layer polymer sub-wavelength grating.Finally, by using of digital mask lithography method polymer SU-8 is used to fabricate plane binary phase grating, and PDMS is used to copy the rectangular structure on the photo-resist grating. The diffraction properties of the fabricated grating sample are tested with constructed experiment setup.