Switching of Electrically Commanded Alignment Layers Probed by Optical Second Harmonic Generation

Abstract

Optical second harmonic generation (SHG) was used to probe the response of a 200 nm thick electrically commanded alignment layer made of ferroelectric liquid crystal polymer (FLCP) film to an external DC electric field. The results show that for the field magnitudes in the range 0–2 V/μm the field induced reorientation effects represent only a relatively minor structural perturbation of the film. The switching process is monostable and shows characteristics of the “V-shaped” switching. The response time of the SHG signal is relatively longer than what is measured for the bulk FLCP. Several mechanisms are considered as possible reasons for that.

Keywords:

• alignment layers
• electrically commanded surfaces
• ferroelectric liquid crystal polymers
• ferroelectric switching
• optical second harmonic generation