Terahertz zone plates with continuous phase

The planar zone plate,light weight, low loss and low cost with simple design, has been extensively studied and used at microwave and millimeterwave frequencies. However, the attenuation in conventional lowloss materials increases at higher frequencies, and dimensional tolerances become smaller, making the fabrication of the terahertz zone plate more difficult. This investigation addressed the design of a zone plate with continuous phase for terahertz frequencies. The relation between the feature size and some important parameters of the zone plate was analyzed, including focal length, F-number, incident frequency and material refractive index, and some factors that affect the plate’s efficiency were discussed. The simulation of intensity distribution on the focal plane and optic axis