Vector Diffraction Of Binary Optical Elements Design And Parallel Direct Write Production

With the development of micro-manufacture technique and computer technology, the feature size of binary optical elements becomes smaller and smaller. If binary optical elements are designed by the scalar diffraction theory, it will lead very monstrous error. So it must be designed by the vector diffraction theory. In this paper, the method of designing subwavelength binary optical elements by rigorous coupled-wave analysis was presented. Antireflective elements, polarizing beam splitters and high-efficiency Dammann gratings were designed based on this method. At the same time, the parallel direct writing was researched. The main contributions of this paper are as follows.1. The antireflective performance of subwavelength gratings was investigated by the rigorous coupled-wave analysis method. Aiming at 1.55μm incident wave, we have designed both one-dimensional antireflective gratings and two-dimensional antireflective gratings. The optical return loss of the gratings we designed is much less than -27dB, the ITU-T (International Telecommunication Union-Telecommunication standardization sector) recommendation was satisfied.2. Wideband, wide angle and high extinction ratios polarizing beam splitters were designed using the rigorous coupled-wave analysis method. The extinction ratios for both reflection side and transmission side are better than 100 when the incident wavelength is varied in the range from 1.27μm to 1.67μm and the incident angle is in the range from 51 degree to 57 degree.3. High-efficiency Dammann gratings were designed based on the genetic algorithm and rigorous coupled-wave analysis theory. The efficiencies of the Dammann gratings we designed are more than 90%, which are greater than the theoretic upper bounds of Dammann gratings designed by the conventional method.4. Some binary optical elements were manufactured by parallel direct writing and inductive couple plasma etching technology. Because the traditional laser direct writing system has some disadvantages, for example, low writing speed and long manufacture period. We propose the parallel direct writing method based on a transmitted intensity-modulating spatial light modulator. It can improve the writing speed owing to its stepper exposure mode. Fresnel lens, Dammann gratings and blazed gratings were manufactured by this method.