Polarized pseudonondiffracting beams generated by polarization-selective diffractive phase elements

The concept and the generation of polarized pseudonondiffracting beams (PNDB’s) from polarization-selective diffractive phase elements (DPE’s) are presented for what we believe is the first time in a monochromatic illuminating system. The polarized PNDB’s behave as segmented almost constant axial-intensity distributions with individual different polarization states in different segments. The pure polarization state in each segment can be arbitrarily preset. The design of polarization-selective DPE’s is achieved with the use of the conjugate-gradient method. The simulation results show that the DPE’s we designed can successfully implement the desired polarization modulation. Furthermore the PNDB’s characteristics of axial-intensity uniformity and beamlike shape are well achieved with the DPE’s we designed.