DOI: 10.1007/s101890070036
Electro-optical phase shift in polymer dispersed liquid crystals
O. LevyCourant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
ohad@cims.nyu.edu
(Received 25 November 1999 and Received in final form 20 January 2000)
Abstract
An anisotropic version of the Maxwell Garnett
approximation is applied for studying the
electro-optical phase modulation by polymer
dispersed liquid crystals (PDLC). The PDLC
contain bipolar liquid crystal droplets that
can be reoriented by an external field causing a
change in the optical birefringence.
This approach provides an explicit link between
the droplet orientation distribution and the
electro-optical phase shift.
For aligned droplets we find that the sharpness
of the change in the birefringence may be
controlled by selecting the initial orientation.
For a planar distribution we find sharp transitions
with a hysteresis loop whose width depends on the
droplet concentration. For a random distribution,
the droplet orientation and the optical phase
shift change more gradually with the applied field.
These results demonstrate that PDLC may be suitable
for a wide range of electro-optic applications
based on their field-induced phase modulation properties.
In addition, it is apparent that the optical phase shift
is quite sensitive to changes in droplet orientation.
It should therefore be useful for studying reorientation
phenomena in PDLC, overcoming the problems due to light scattering in
these materials.
42.70.Df - Liquid crystals.
78.20.Jq - Electro-optical effects.
78.66.Sq - Composite materials.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2000
