Document Abstract
A
general
theory
of
the
two-beam
coupling
between
a
pump
beam
and
a
signal
beam
in
photorefractive
materials
is
presented.
The
coupled
wave
equations
describing
the
non-linear
two
beam
coupling
are
derived,
based
on
Maxwell’s
wave
equation.
The
coupled
equation
for
the
intensities
of
the
two
beams
in
the
photorefractive
crystals
with
the
absorbing
properties
have
been
derived
analytically.
The
intensity
of
the
signal
beam
increases
with
the
increasing
crystal
thickness,
reaches
a
maximum
and
then
decreases.
The
influence
of
energy
beam
coupling
coefficient,
oscillation
frequency
shift,
crystal
thickness,
absorp
tion
coefficient
and
the
input
beam
intensity
ratio
on
the
signal
beam
intensity
have
been
studied
in
details.
The
effect
of
the
photoconductivity
of
the
materials
on
the
intensities
of
the
two
beams
in
both
the
co-directional
as
well
as
contra-directional
two
beam
coupling
cases
have
been
studied.