Research On Liquid Crystal Optical Phase Modulation Device Based On DMD Multiple Exposure System

Liquid crystal(LC)is widely used in the fields of optical display and non-display due to its excellent photoelectric characteristics.In the non-display field,it can be based on the Pancharatnam-Berry phase theory,through the LC photoalignment technology to align the arrangement of molecular optical axes of different structures to fabricate different LC optical phase modulation devices(LCOPMD).Compared with the traditional dynamic phase-based optical modulation device,the LCOPMD has the characteristics of small volume,light weight,high integration,and can complete the efficient and convenient modulation of the beam.These LCOPMDs can be used not only in the fields of holography and nonlinear optics,but also in the regulation of structured light fields to achieve the generation of beams with specific structures.This article is mainly based on the Pancharatnam-Berry phase theory,combined with the LC photoalignment technology and digital micro-mirror device(DMD)multiple exposure system to achieve the preparation and testing of single phase structure and composite phase structure LCOPMDs.Through this method,the fabrication of the LCOPMD can be easily achieved,and the phase structure of the two devices can be synthesized to fabricate an optical modulation device with a composite function,which has huge potential applications in the integrated optics.The main research works of this article are summarized as follows:(1)Based on the LC photoalignment technology and DMD multiple exposure system,four kinds of LCOPMDs with single phase structure were fabricated and tested.The fabricated four types of LCOPMDs with a single phase structure are respectively LC polarization grating,LC vortex q-plate,LC Airy cubic phase plate and LC Airy symmetric cubic phase plate.The fabricated four single-phase LCOPMDs were tested respectively,and the experimental results consistent with the theory.Completed the verification of the diffraction effect of the LC polarizing grating,the vortex beam generated by the LC vortex q-plate modulation,the airy beam generated by the LC Airy cubic phase plate modulation,and the symmetrical airy beam generated by the LC Airy symmetric cubic phase plate modulation.(2)Based on the LC photoalignment technology and the DMD multiple exposure system,three kinds of composite phase structure LCOPMDs have been fabricated and tested.The three kinds of LCOPMDs fabricated with the composite phase structure are respectively LC fork polarizing grating,LC vortex Airy cubic phase plate and LC vortex Airy symmetric cubic phase plate.The fabricated three kinds of LCOPMDs with composite phase structures were tested respectively,and the experimental results also consistent with the theory.The diffraction effect and ability to modulate vortex beam of the LC fork polarizing grating,the modulation of LC vortex Airy cubic phase plate generates vortex Airy beam,and the modulation of LC vortex Airy symmetric cubic phase plate generates symmetric Airy vortex beam and symmetric Airy vector beam have been respectively verified.