<s>
Nanophotonics	B-Algorithm
or	O
nano-optics	B-Algorithm
is	O
the	O
study	O
of	O
the	O
behavior	O
of	O
light	O
on	O
the	O
nanometer	O
scale	O
,	O
and	O
of	O
the	O
interaction	O
of	O
nanometer-scale	O
objects	O
with	O
light	O
.	O
</s>
<s>
It	O
is	O
a	O
branch	O
of	O
optics	B-Algorithm
,	O
optical	O
engineering	O
,	O
electrical	O
engineering	O
,	O
and	O
nanotechnology	O
.	O
</s>
<s>
The	O
term	O
"	O
nano-optics	B-Algorithm
"	O
,	O
just	O
like	O
the	O
term	O
"	O
optics	B-Algorithm
"	O
,	O
usually	O
refers	O
to	O
situations	O
involving	O
ultraviolet	B-Application
,	O
visible	O
,	O
and	O
near-infrared	O
light	O
(	O
free-space	O
wavelengths	O
from	O
300	O
to	O
1200	O
nanometers	O
)	O
.	O
</s>
<s>
Nanophotonics	B-Algorithm
researchers	O
pursue	O
a	O
very	O
wide	O
variety	O
of	O
goals	O
,	O
in	O
fields	O
ranging	O
from	O
biochemistry	O
to	O
electrical	O
engineering	O
to	O
carbon-free	O
energy	O
.	O
</s>
<s>
Integrated	O
circuits	O
are	O
made	O
using	O
photolithography	B-Algorithm
,	O
i.e.	O
</s>
<s>
Using	O
various	O
techniques	O
such	O
as	O
immersion	B-Algorithm
lithography	I-Algorithm
and	O
phase-shifting	O
photomasks	B-Algorithm
,	O
it	O
has	O
indeed	O
been	O
possible	O
to	O
make	O
images	O
much	O
finer	O
than	O
the	O
wavelength	O
—	O
for	O
example	O
,	O
drawing	O
30nm	O
lines	O
using	O
193nm	O
light	O
.	O
</s>
<s>
Heat-assisted	O
magnetic	O
recording	O
is	O
a	O
nanophotonic	B-Algorithm
approach	O
to	O
increasing	O
the	O
amount	O
of	O
data	O
that	O
a	O
magnetic	O
disk	O
drive	O
can	O
store	O
.	O
</s>
<s>
Researchers	O
have	O
investigated	O
a	O
variety	O
of	O
nanophotonic	B-Algorithm
techniques	O
to	O
intensify	O
light	O
in	O
the	O
optimal	O
locations	O
within	O
a	O
solar	O
cell	O
.	O
</s>
<s>
Nanophotonics	B-Algorithm
has	O
also	O
been	O
implicated	O
in	O
aiding	O
the	O
controlled	O
and	O
on-demand	O
release	O
of	O
anti-cancer	O
therapeutics	O
like	O
adriamycin	O
from	O
nanoporous	O
optical	O
antennas	O
to	O
target	O
triple-negative	O
breast	O
cancer	O
and	O
mitigate	O
exocytosis	O
anti-cancer	O
drug	O
resistance	O
mechanisms	O
and	O
therefore	O
circumvent	O
toxicity	O
to	O
normal	O
systemic	O
tissues	O
and	O
cells	O
.	O
</s>
<s>
Using	O
nanophotonics	B-Algorithm
to	O
create	O
high	O
peak	O
intensities	O
:	O
If	O
a	O
given	O
amount	O
of	O
light	O
energy	O
is	O
squeezed	O
into	O
a	O
smaller	O
and	O
smaller	O
volume	O
(	O
"	O
hot-spot	O
"	O
)	O
,	O
the	O
intensity	O
in	O
the	O
hot-spot	O
gets	O
larger	O
and	O
larger	O
.	O
</s>
<s>
This	O
is	O
especially	O
helpful	O
in	O
nonlinear	O
optics	B-Algorithm
;	O
an	O
example	O
is	O
surface-enhanced	B-Algorithm
Raman	I-Algorithm
scattering	I-Algorithm
.	O
</s>
<s>
One	O
goal	O
of	O
nanophotonics	B-Algorithm
is	O
to	O
construct	O
a	O
so-called	O
"	O
superlens	O
"	O
,	O
which	O
would	O
use	O
metamaterials	O
(	O
see	O
below	O
)	O
or	O
other	O
techniques	O
to	O
create	O
images	O
that	O
are	O
more	O
accurate	O
than	O
the	O
diffraction	O
limit	O
(	O
deep	O
subwavelength	O
)	O
.	O
</s>
<s>
Near-field	O
scanning	O
optical	O
microscope	O
(	O
NSOM	O
or	O
SNOM	O
)	O
is	O
a	O
quite	O
different	O
nanophotonic	B-Algorithm
technique	O
that	O
accomplishes	O
the	O
same	O
goal	O
of	O
taking	O
images	O
with	O
resolution	O
far	O
smaller	O
than	O
the	O
wavelength	O
.	O
</s>
<s>
Nanophotonics	B-Algorithm
in	O
the	O
form	O
of	O
subwavelength	O
near-field	O
optical	O
structures	O
,	O
either	O
separate	O
from	O
the	O
recording	O
media	O
,	O
or	O
integrated	O
into	O
the	O
recording	O
media	O
,	O
were	O
used	O
to	O
achieve	O
optical	O
recording	O
densities	O
much	O
higher	O
than	O
the	O
diffraction	O
limit	O
allows	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
titanium	O
dioxide	O
,	O
structures	O
on	O
the	O
order	O
of	O
less	O
than	O
200nm	O
half-height	O
width	O
will	O
absorb	O
not	O
only	O
in	O
the	O
normal	O
ultraviolet	B-Application
part	O
of	O
the	O
solar	O
spectrum	O
,	O
but	O
well	O
into	O
the	O
high-energy	O
visible	O
blue	O
as	O
well	O
.	O
</s>
<s>
Silicon	O
photonics	O
is	O
a	O
silicon-based	O
subfield	O
of	O
nanophotonics	B-Algorithm
in	O
which	O
nano-scale	O
structures	O
of	O
the	O
optoelectronic	O
devices	O
realized	O
on	O
silicon	O
substrates	O
and	O
that	O
are	O
capable	O
to	O
control	O
both	O
light	O
and	O
electrons	O
.	O
</s>
<s>
This	O
was	O
originally	O
used	O
in	O
radio	O
and	O
microwave	B-Algorithm
engineering	I-Algorithm
,	O
where	O
metal	O
antennas	O
and	O
waveguides	O
may	O
be	O
hundreds	O
of	O
times	O
smaller	O
than	O
the	O
free-space	O
wavelength	O
.	O
</s>
<s>
Many	O
nano-optics	B-Algorithm
designs	O
look	O
like	O
common	O
microwave	O
or	O
radiowave	O
circuits	O
,	O
but	O
shrunk	O
down	O
by	O
a	O
factor	O
of	O
100,000	O
or	O
more	O
.	O
</s>
<s>
At	O
very	O
high	O
frequencies	O
(	O
near	O
and	O
above	O
the	O
plasma	O
frequency	O
,	O
usually	O
ultraviolet	B-Application
)	O
,	O
the	O
permittivity	O
of	O
a	O
metal	O
is	O
not	O
so	O
large	O
,	O
and	O
the	O
metal	O
stops	O
being	O
useful	O
for	O
concentrating	O
fields	O
.	O
</s>
<s>
Metallic	O
parallel-plate	O
waveguides	O
(	O
striplines	O
)	O
,	O
lumped-constant	O
circuit	O
elements	O
such	O
as	O
inductance	O
and	O
capacitance	O
(	O
at	O
visible	O
light	O
frequencies	O
,	O
the	O
values	O
of	O
the	O
latter	O
being	O
of	O
the	O
order	O
of	O
femtohenries	O
and	O
attofarads	O
,	O
respectively	O
)	O
,	O
and	O
impedance-matching	O
of	O
dipole	O
antennas	O
to	O
transmission	O
lines	O
,	O
all	O
familiar	O
techniques	O
at	O
microwave	O
frequencies	O
,	O
are	O
some	O
current	O
areas	O
of	O
nanophotonics	B-Algorithm
development	O
.	O
</s>
<s>
That	O
said	O
,	O
there	O
are	O
a	O
number	O
of	O
very	O
important	O
differences	O
between	O
nano-optics	B-Algorithm
and	O
scaled-down	O
microwave	O
circuits	O
.	O
</s>
<s>
Fourier	B-Algorithm
transform	I-Algorithm
of	O
a	O
spatial	O
field	O
distribution	O
consists	O
of	O
different	O
spatial	O
frequencies	O
.	O
</s>
<s>
In	O
nanophotonics	B-Algorithm
,	O
strongly	O
localized	O
radiation	O
sources	O
(	O
dipolar	O
emitters	O
such	O
as	O
fluorescent	O
molecules	O
)	O
are	O
often	O
studied	O
.	O
</s>
<s>
Evanescent	O
components	O
exist	O
only	O
in	O
the	O
near	B-Algorithm
field	I-Algorithm
of	O
the	O
emitter	O
and	O
decay	O
without	O
transferring	O
net	O
energy	O
to	O
the	O
far	B-Algorithm
field	I-Algorithm
.	O
</s>
<s>
Nanophotonics	B-Algorithm
is	O
primarily	O
concerned	O
with	O
the	O
near-field	O
evanescent	O
waves	O
.	O
</s>
