Large aperture and defect-free liquid crystal planar optics enabled by high-throughput pulsed polarization patterning

Area of Science:

• Optics and Photonics
• Materials Science
• Polymer Science

Background:

• Liquid crystal (LC) geometrical phase optics offer advanced optical properties and stimuli-responsive behaviors for planar optics.
• Fabrication of large-aperture LC elements with controlled molecular orientation is crucial for practical applications.

Purpose of the Study:

• To develop a novel technique for fabricating large-aperture, defect-free LC geometrical phase elements.
• To investigate the response of azo photo-alignment materials to pulsed laser light for improved patterning.

Main Methods:

• Proposed a pulsed polarization patterning technique using nanosecond laser pulses.
• Investigated azo photo-alignment material response and LC anchoring behaviors.
• Implemented a flying exposure mode with high-frequency modulated polarized laser pulses (8 kHz) and servo auto-focusing for large-aperture patterning.

Main Results:

• Reduced the recording threshold to one fourth compared to continuous wave recording.
• Achieved enhanced patterning resolution of approximately 0.71 µm.
• Successfully fabricated a 4-inch aperture LC polarization grating with 99.2% average diffraction efficiency.

Conclusions:

• The pulsed polarization patterning technique is effective for creating high-resolution, large-aperture LC geometrical phase elements.
• This advancement enables stable and reliable fabrication for next-generation planar optics.
• Demonstrated high diffraction efficiency, highlighting the practical utility of the developed elements.