Phase profile optimization of silicon multi-phase zone plate lenses for operation at 585 GHz frequency

Phase profile of the multi-phase zone plate (MPZP) was optimized for efficient lens operation at 0.585 THz frequency. Different type of the MPZP samples with a focal length of about 13 mm and a focal number of 1 were designed of high-resistivity silicon. The depth and size of initial eight step phase profile were optimized in the most outer subzone areas. Successful optimization of the phase profile allowed us to reduce manufacturing complexity and achieve higher focusing gain values in comparison to respective classical design MPZP.