Liquid crystal polymer vector vortex waveplates with sub-micrometer singularity

Small singularity size is critical for achieving low light loss and high contrast for vector vortex waveplate (VVW) based coronagraph. In the opto-mechanical system for recording VVW with photoalignment, reshaping the center light intensity distribution and precision alignment can effectively decrease singularity size. We have developed methods for redistributing the light intensity near the singularity. A new direct alignment method is introduced. This method helps in reaching the optimized alignment position by allowing to depict the beam profile at the photoalignment surface. Employing these techniques and new liquid crystal polymer materials, we have fabricated VVWs with sub-micrometer defect size for UV, and subs-wavelength defect size for 1.5 micrometer wavelength range. Inversely twisted layers method was used for fabrication of broadband VVW for the near infrared region.