Laser-induced instabilities in liquid crystal cells with a photosensitive substrate

Area of Science:

• Physics
• Materials Science

Background:

• Investigated liquid crystal (LC) layers confined between a reference plate and a photosensitive substrate.
• Focused on a reverse geometry configuration with laser illumination from the reference side.

Purpose of the Study:

• To investigate static and dynamic instabilities in planar liquid crystal cells.
• To understand the influence of laser polarization angle relative to director orientation.
• To explore instabilities in cells with molecules aligned normal to the reference plate.

Main Methods:

• Utilized a reverse geometry setup for liquid crystal cell illumination.
• Varied the angle between laser polarization and director orientation in planar cells.
• Observed molecular alignment along the normal in specific cell configurations.
• Employed light scattering techniques to characterize instabilities.

Main Results:

• Observed both static and dynamic instabilities in planar cells, dependent on polarization angle.
• Detected dynamic patterns in cells with normal molecular alignment, irrespective of polarization angle.
• Confirmed findings with a model based on photoinduced surface torque.
• Characterized instability properties through light scattering.

Conclusions:

• A photoinduced surface torque model successfully explains observed liquid crystal instabilities.
• Molecular alignment significantly influences the type of instability observed.
• Light scattering provides insights into the fundamental properties of these photoinduced instabilities.