This study demonstrates all optical switches between the four diffractive light levels of a body-centered tetragonal
photonic crystal. The sample is based on holographic polymer-dispersed liquid crystals that are fabricated using a twobeam interference with multiple exposures. The switching mechanism bases on the effective index modulation of the PC that contains a liquid crystal/azo-dye mixture could be controlled by two pumping laser beams. The switching time between the blue-laser-pumped and the blue-and-green-laser-pumped levels is fast.
Two-dimensional (2-D) square lattice (SL) photonic crystals (PCs) are fabricated and their optical/electro-optical
properties are studied. The PCs are based on polymer-dispersed liquid crystals (PDLC) that are formed using twobeam
interference with double-exposures. The PC structure that is observed using a scanning electron microscope
(SEM) matches with the calculated interference pattern. The results of optical/electro-optical studies demonstrate
that superprism and negative refraction effects occur at certain incident angles over a range of frequencies, and are
consistent with the simulated ones. Moreover, the negative refraction efficiency is electrically controllable.
The superprism and lasing devices were demonstrated using holographic polymer-dispersed liquid crystal (HPDLC) films. The HPDLC film for superprism application was designed and fabricated using three coplanar beams. The fabricated HPDLC film contained two-dimensional (2D) ordered nano-sized LC domains (~150nm in diameter) embedded in a polymer matrix; its periodicity was estimated using a scanning electron microscope to be ~350nm. The dispersion of white light from this HPDLC superprism was ~50°, and the deflection of light output from it was consistent with the theoretical value obtained by the pland wave expansion method. HPDLC for laser application was fabricated using two counter-propagation laser beams similar to those used in standard holography. The structure has a periodicity in the range of optical wavelength, and reflects light selectively as governed by Bragg reflection. Doped with a laser dye whose emission spectrum overlaps the reflection spectrum of the grating, the HPDLC reflection grating can be lased at the band edges of the reflection band gap. The details of the experiments, results will be reported.
The polarization-dependent superprism phenomenon was demonstrated using holographic polymer-dispersed liquid
crystal (HPDLC) films. The HPDLC film is designed and fabricated using three coplanar beams. The fabricated HPDLC
film contained two-dimensional (2D) ordered nano-sized LC domains (~150nm in diameter) embedded in a polymer
matrix; its periodicity was estimated using a scanning electron microscope to be ~350nm. The dispersion of white light
from this HPDLC superprism was ~50°, and the deflection of light output from it was consistent with the theoretical
value obtained by the plane wave expansion method.
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