<s>
Electro-optic	O
rectification	O
(	O
EOR	O
)	O
,	O
also	O
referred	O
to	O
as	O
optical	B-Algorithm
rectification	I-Algorithm
,	O
is	O
a	O
non-linear	O
optical	O
process	O
that	O
consists	O
of	O
the	O
generation	O
of	O
a	O
quasi-DC	O
polarization	O
in	O
a	O
non-linear	O
medium	O
at	O
the	O
passage	O
of	O
an	O
intense	O
optical	O
beam	O
.	O
</s>
<s>
For	O
typical	O
intensities	O
,	O
optical	B-Algorithm
rectification	I-Algorithm
is	O
a	O
second-order	O
phenomenon	O
which	O
is	O
based	O
on	O
the	O
inverse	O
process	O
of	O
the	O
electro-optic	O
effect	O
.	O
</s>
<s>
Optical	B-Algorithm
rectification	I-Algorithm
can	O
be	O
intuitively	O
explained	O
in	O
terms	O
of	O
the	O
symmetry	O
properties	O
of	O
the	O
non-linear	O
medium	O
:	O
in	O
the	O
presence	O
of	O
a	O
preferred	O
internal	O
direction	O
,	O
the	O
polarization	O
will	O
not	O
reverse	O
its	O
sign	O
at	O
the	O
same	O
time	O
as	O
the	O
driving	O
field	O
.	O
</s>
<s>
Optical	B-Algorithm
rectification	I-Algorithm
is	O
analogous	O
to	O
the	O
electric	B-Algorithm
rectification	I-Algorithm
effect	I-Algorithm
produced	O
by	O
diodes	O
,	O
wherein	O
an	O
AC	O
signal	O
can	O
be	O
converted	O
(	O
"	O
rectified	O
"	O
)	O
to	O
DC	O
.	O
</s>
<s>
A	O
diode	O
can	O
turn	O
a	O
sinusoidal	O
electric	O
field	O
into	O
a	O
DC	O
current	O
,	O
while	O
optical	B-Algorithm
rectification	I-Algorithm
can	O
turn	O
a	O
sinusoidal	O
electric	O
field	O
into	O
a	O
DC	O
polarization	O
,	O
but	O
not	O
a	O
DC	O
current	O
.	O
</s>
<s>
Therefore	O
,	O
if	O
the	O
incident	O
light	O
is	O
getting	O
more	O
and	O
more	O
intense	O
,	O
optical	B-Algorithm
rectification	I-Algorithm
causes	O
a	O
DC	O
current	O
,	O
while	O
if	O
the	O
light	O
is	O
getting	O
less	O
and	O
less	O
intense	O
,	O
optical	B-Algorithm
rectification	I-Algorithm
causes	O
a	O
DC	O
current	O
in	O
the	O
opposite	O
direction	O
.	O
</s>
<s>
But	O
again	O
,	O
if	O
the	O
light	O
intensity	O
is	O
constant	O
,	O
optical	B-Algorithm
rectification	I-Algorithm
cannot	O
cause	O
a	O
DC	O
current	O
.	O
</s>
<s>
The	O
mixing	O
of	O
different	O
frequency	O
components	O
produces	O
a	O
beating	O
polarization	O
,	O
which	O
results	O
in	O
the	O
emission	O
of	O
electromagnetic	O
waves	O
in	O
the	O
terahertz	B-Architecture
region	O
.	O
</s>
<s>
Optical	B-Algorithm
rectification	I-Algorithm
also	O
occurs	O
on	O
metal	O
surfaces	O
by	O
similar	O
effect	O
as	O
surface	O
second	O
harmonic	O
generation	O
.	O
</s>
<s>
Similar	O
to	O
other	O
nonlinear	O
optical	O
processes	O
,	O
optical	B-Algorithm
rectification	I-Algorithm
is	O
also	O
reported	O
to	O
become	O
enhanced	O
when	O
surface	O
plasmons	O
are	O
excited	O
on	O
a	O
metal	O
surface	O
.	O
</s>
<s>
Together	O
with	O
carrier	O
acceleration	O
in	O
semiconductors	O
and	O
polymers	O
,	O
optical	B-Algorithm
rectification	I-Algorithm
is	O
one	O
of	O
the	O
main	O
mechanisms	O
for	O
the	O
generation	O
of	O
terahertz	B-Architecture
radiation	I-Architecture
using	O
lasers	O
.	O
</s>
<s>
This	O
is	O
different	O
from	O
other	O
processes	O
of	O
terahertz	B-Architecture
generation	O
such	O
as	O
polaritonics	O
where	O
a	O
polar	O
lattice	O
vibration	O
is	O
thought	O
to	O
generate	O
the	O
terahertz	B-Architecture
radiation	I-Architecture
.	O
</s>
