<s>
Photomixing	B-Algorithm
is	O
the	O
generation	O
of	O
continuous	O
wave	O
terahertz	B-Architecture
radiation	I-Architecture
from	O
two	O
lasers	O
.	O
</s>
<s>
The	O
beams	O
are	O
mixed	O
together	O
and	O
focused	O
onto	O
a	O
photomixer	B-Algorithm
device	O
which	O
generates	O
the	O
terahertz	B-Architecture
radiation	I-Architecture
.	O
</s>
<s>
A	O
typical	O
photoconductive	O
device	O
or	O
'	O
photomixer	B-Algorithm
 '	O
is	O
made	O
from	O
low	O
temperature	O
GaAs	O
with	O
a	O
patterned	O
metalized	O
layer	O
which	O
is	O
used	O
to	O
form	O
an	O
electrode	O
array	O
and	O
radiating	O
antenna	O
.	O
</s>
<s>
The	O
photomixing	B-Algorithm
source	O
can	O
then	O
form	O
the	O
basis	O
of	O
a	O
laser	O
spectrometer	O
which	O
can	O
be	O
used	O
to	O
examine	O
the	O
THz	O
signature	O
of	O
various	O
subjects	O
such	O
as	O
gases	O
,	O
liquids	O
or	O
solid	O
materials	O
.	O
</s>
<s>
The	O
photomixer	B-Algorithm
device	O
converts	O
the	O
beatnote	O
into	O
THz	B-Architecture
radiation	I-Architecture
,	O
often	O
emitted	O
into	O
free	O
space	O
by	O
an	O
integrated	O
antenna	O
.	O
</s>
<s>
Alternatively	O
a	O
second	O
photomixer	B-Algorithm
device	O
can	O
be	O
used	O
as	O
a	O
detector	O
and	O
has	O
the	O
advantage	O
of	O
allowing	O
coherent	O
detection	O
.	O
</s>
