|
The electrooptic effects originate from the change of index of
refraction when an external electric field is applied to a
material.The control of the amplitutde, phase, mory and
direction of propagation of optical wave in the material can
all be related to the change of index of refraction. The PLZT
material has nowadays been applied to some electrooptic devices
due to its ferroelectric properties, high transparency and its
well-performed electrooptic effects even in the form of non-
single crystal. However, the ceramic materials have always
exhibited serious problems such as fatigue and aging phenomena
which may be mainly caused by large applied voltage. If we can
manage to enhance the electrooptic effects of the material,
then the external voltage applied can be made comparably lower,
and thus the aging problem can be reduced considerably。The
enhancement of the electrooptic effects with lower operating
voltage can be realized in the fabrication process of the
material. In this thesis, we make some measurements on PLZT
(9.5/65/35) coated with SiO2 and gold thin films of low
constant and weak conductivity using co-planar electrode The
results show that the component perpendicular to the of the
incidenting light (z-direction) of the applied electric field
is enhanced considerably due to the weak dielectrictiy of the
thin film layer. The optical retardations of sample are
observed to increase 35% by coating with a SiO2 thin film ,and
57% by coating with a gold thin film. The half-wave voltage is
decreased, the operating voltage is decreased, and the fatigue
and aging phenomena in devices are reduced considerably.
|