<s>
A	O
subwavelength-diameter	B-Device
optical	I-Device
fibre	I-Device
(	O
SDF	O
or	O
SDOF	O
)	O
is	O
an	O
optical	B-Architecture
fibre	I-Architecture
whose	O
diameter	O
is	O
less	O
than	O
the	O
wavelength	O
of	O
the	O
light	O
being	O
propagated	O
through	O
it	O
.	O
</s>
<s>
An	O
SDF	O
usually	O
consists	O
of	O
long	O
thick	O
parts	O
(	O
same	O
as	O
conventional	O
optical	B-Architecture
fibres	I-Architecture
)	O
at	O
both	O
ends	O
,	O
transition	O
regions	O
(	O
tapers	O
)	O
where	O
the	O
fibre	O
diameter	O
gradually	O
decreases	O
down	O
to	O
the	O
subwavelength	O
value	O
,	O
and	O
a	O
subwavelength-diameter	O
waist	O
,	O
which	O
is	O
the	O
main	O
acting	O
part	O
.	O
</s>
<s>
Due	O
to	O
such	O
a	O
strong	O
geometrical	O
confinement	O
,	O
the	O
guided	O
electromagnetic	O
field	O
in	O
an	O
SDF	O
is	O
restricted	O
to	O
a	O
single	B-Device
mode	O
called	O
fundamental	O
.	O
</s>
<s>
The	O
names	O
in	O
use	O
include	O
subwavelength	O
waveguide	O
,	O
subwavelength	O
optical	O
wire	O
,	O
subwavelength-diameter	O
silica	O
wire	O
,	O
subwavelength	B-Device
diameter	I-Device
fibre	I-Device
taper	O
,	O
(	O
photonic	O
)	O
wire	O
waveguide	O
,	O
photonic	O
wire	O
,	O
photonic	O
nanowire	B-Architecture
,	O
optical	O
nanowires	B-Architecture
,	O
optical	B-Architecture
fibre	I-Architecture
nanowires	B-Architecture
,	O
tapered	O
(	O
optical	O
)	O
fibre	O
,	O
fibre	O
taper	O
,	O
submicron-diameter	O
silica	O
fibre	O
,	O
ultrathin	B-Device
optical	I-Device
fibres	I-Device
,	O
optical	O
nanofibre	O
,	O
optical	B-Device
microfibres	I-Device
,	O
submicron	B-Algorithm
fibre	O
waveguides	O
,	O
micro/nano	O
optical	O
wires	O
(	O
MNOW	O
)	O
.	O
</s>
<s>
The	O
term	O
submicron	B-Algorithm
is	O
often	O
synonymous	O
to	O
subwavelength	O
,	O
as	O
the	O
majority	O
of	O
experiments	O
are	O
carried	O
out	O
using	O
light	O
with	O
a	O
wavelength	O
between	O
0.5	O
and	O
1.6µm	O
.	O
</s>
<s>
An	O
SDF	O
is	O
usually	O
created	O
by	O
tapering	O
a	O
commercial	O
,	O
usually	O
step-index	B-Device
,	O
optical	B-Architecture
fibre	I-Architecture
.	O
</s>
<s>
An	O
optical	B-Architecture
fibre	I-Architecture
usually	O
consists	O
of	O
a	O
core	O
,	O
a	O
cladding	B-Device
,	O
and	O
a	O
protective	O
coating	O
.	O
</s>
<s>
Before	O
pulling	O
a	O
fibre	O
,	O
its	O
coating	O
is	O
removed	O
(	O
i.e.	O
,	O
the	O
fibre	O
is	O
stripped	B-Device
)	O
.	O
</s>
<s>
In	O
order	O
to	O
minimize	O
the	O
losses	O
of	O
light	O
to	O
unbound	B-Device
modes	I-Device
,	O
one	O
must	O
control	O
the	O
pulling	O
process	O
so	O
that	O
the	O
tapering	O
angles	O
satisfy	O
the	O
adiabatic	O
condition	O
by	O
not	O
exceeding	O
a	O
certain	O
value	O
,	O
usually	O
in	O
the	O
order	O
of	O
a	O
few	O
milliradian	O
.	O
</s>
