Dynamic response of large tilt-angle flexoelectro-optic liquid crystal modulators.

Area of Science:

• Optics and Photonics
• Materials Science
• Liquid Crystal Displays

Background:

• Flexoelectro-optic liquid crystal modulators (FLCs) offer potential for high-speed spatial light modulation (>1 kHz).
• Large-tilt (>45°) FLC devices are crucial for next-generation analog phase spatial light modulators (SLMs) used in beamsteering and microscopy.
• Previous studies lacked time-resolved data for large-tilt FLC devices, hindering understanding of dynamic switching behaviors.

Purpose of the Study:

• To perform the first time-resolved tilt-angle and retardance measurements on large-tilt FLC devices.
• To investigate the dynamic switching behavior and identify sources of error in these modulators.
• To provide data for correcting deterministic errors and enabling practical SLM applications.

Main Methods:

• Utilized a chiral nematic liquid crystal device (CBC7CB and R5011 dopant) in a 5 µm-thick cell, aligned in the uniform lying helix mode.
• Performed time-resolved measurements of tilt-angle and retardance during dynamic switching over angles of ± 54°.
• Analyzed the influence of electric field polarity, pulse history, and applied field on optic-axis behavior.

Main Results:

• Observed retardance changes up to 0.17λ during dynamic switching.
• Revealed an asymmetry in optic-axis tilt dependent on electric field polarity.
• Identified pattern dependence in optic-axis change, leading to tilt-angle errors up to 8.8° (phase errors up to 35.2°).

Conclusions:

• Time-resolved measurements are essential for understanding and correcting errors in large-tilt FLC devices.
• The observed pattern dependence and tilt-angle errors can be addressed through these measurements, paving the way for practical SLMs.
• This research enables the development of advanced optical beamsteering, microscopy, and micromachining technologies.