<s>
In	O
fiber-optic	B-Application
communication	I-Application
,	O
a	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
(	O
SMF	O
)	O
,	O
also	O
known	O
as	O
fundamental	O
-	O
or	O
mono-mode	O
,	O
is	O
an	O
optical	B-Architecture
fiber	I-Architecture
designed	O
to	O
carry	O
only	O
a	O
single	O
mode	O
of	O
light	O
-	O
the	O
transverse	O
mode	O
.	O
</s>
<s>
The	O
2009	O
Nobel	O
Prize	O
in	O
Physics	O
was	O
awarded	O
to	O
Charles	O
K	O
.	O
Kao	O
for	O
his	O
theoretical	O
work	O
on	O
the	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
.	O
</s>
<s>
The	O
standards	O
G.652	O
and	O
G.657	O
define	O
the	O
most	O
widely	O
used	O
forms	O
of	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
.	O
</s>
<s>
They	O
made	O
cylindrical	O
preforms	O
by	O
depositing	O
purified	O
materials	O
from	O
the	O
vapor	O
phase	O
,	O
adding	O
carefully	O
controlled	O
levels	O
of	O
dopants	O
to	O
make	O
the	O
refractive	O
index	O
of	O
the	O
core	O
slightly	O
higher	O
than	O
that	O
of	O
the	O
cladding	B-Device
,	O
without	O
raising	O
attenuation	O
dramatically	O
.	O
</s>
<s>
Like	O
multi-mode	B-Device
optical	I-Device
fibers	I-Device
,	O
single-mode	O
fibers	O
do	O
exhibit	O
modal	B-Device
dispersion	I-Device
resulting	O
from	O
multiple	O
spatial	O
modes	O
but	O
with	O
narrower	O
modal	B-Device
dispersion	I-Device
.	O
</s>
<s>
Single-mode	O
fibers	O
are	O
therefore	O
better	O
at	O
retaining	O
the	O
fidelity	O
of	O
each	O
light	O
pulse	O
over	O
longer	O
distances	O
than	O
multi-mode	B-Device
fibers	I-Device
.	O
</s>
<s>
For	O
these	O
reasons	O
,	O
single-mode	O
fibers	O
can	O
have	O
a	O
higher	O
bandwidth	O
than	O
multi-mode	B-Device
fibers	I-Device
.	O
</s>
<s>
Equipment	O
for	O
single-mode	O
fiber	O
is	O
more	O
expensive	O
than	O
equipment	O
for	O
multi-mode	B-Device
optical	I-Device
fiber	I-Device
,	O
but	O
the	O
single-mode	O
fiber	O
itself	O
is	O
usually	O
cheaper	O
in	O
bulk	O
.	O
</s>
<s>
A	O
typical	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
has	O
a	O
core	O
diameter	O
between	O
8	O
and	O
10.5	O
µm	O
and	O
a	O
cladding	B-Device
diameter	O
of	O
125µm	O
.	O
</s>
<s>
There	O
are	O
a	O
number	O
of	O
special	O
types	O
of	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
which	O
have	O
been	O
chemically	O
or	O
physically	O
altered	O
to	O
give	O
special	O
properties	O
,	O
such	O
as	O
dispersion-shifted	B-Device
fiber	I-Device
and	O
nonzero	B-Architecture
dispersion-shifted	I-Architecture
fiber	I-Architecture
.	O
</s>
<s>
,	O
data	O
rates	O
of	O
up	O
to	O
10	O
gigabits	O
per	O
second	O
were	O
possible	O
at	O
distances	O
of	O
over	O
with	O
commercially	O
available	O
transceivers	O
(	O
Xenpak	B-Protocol
)	O
.	O
</s>
<s>
The	O
lowest-order	O
bounds	O
mode	O
is	O
ascertained	O
for	O
the	O
wavelength	O
of	O
interest	O
by	O
solving	O
Maxwell	O
's	O
equations	O
for	O
the	O
boundary	O
conditions	O
imposed	O
by	O
the	O
fiber	O
,	O
which	O
are	O
determined	O
by	O
the	O
core	O
diameter	O
and	O
the	O
refractive	O
indices	O
of	O
the	O
core	O
and	O
cladding	B-Device
.	O
</s>
<s>
In	O
step-index	O
guides	O
,	O
single-mode	O
operation	O
occurs	O
when	O
the	O
normalized	B-Device
frequency	I-Device
,	O
V	O
,	O
is	O
less	O
than	O
or	O
equal	O
to	O
2.405	O
.	O
</s>
<s>
OS1	O
and	O
OS2	O
are	O
standard	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
used	O
with	O
wavelengths	O
1310nm	O
and	O
1550nm	O
(	O
size	O
9/125µm	O
)	O
with	O
a	O
maximum	O
attenuation	O
of	O
1dB/km	O
(	O
OS1	O
)	O
and	O
0.4dB/km	O
(	O
OS2	O
)	O
.	O
</s>
<s>
Optical	B-Device
fiber	I-Device
connectors	I-Device
are	O
used	O
to	O
join	O
optical	B-Architecture
fibers	I-Architecture
where	O
a	O
connect/disconnect	O
capability	O
is	O
required	O
.	O
</s>
<s>
Due	O
to	O
the	O
sophisticated	O
polishing	O
and	O
tuning	O
procedures	O
that	O
may	O
be	O
incorporated	O
into	O
optical	B-Device
connector	I-Device
manufacturing	O
,	O
connectors	O
are	O
generally	O
assembled	O
onto	O
optical	B-Architecture
fiber	I-Architecture
in	O
a	O
supplier	O
's	O
manufacturing	O
facility	O
.	O
</s>
<s>
Optical	B-Device
fiber	I-Device
connectors	I-Device
are	O
used	O
in	O
telephone	O
company	O
central	O
offices	O
,	O
at	O
installations	O
on	O
customer	O
premises	O
,	O
and	O
in	O
outside	O
plant	O
applications	O
.	O
</s>
<s>
The	O
latest	O
industry	O
requirements	O
for	O
optical	B-Device
fiber	I-Device
connectors	I-Device
are	O
in	O
Telcordia	O
,	O
Generic	O
Requirements	O
for	O
Singlemode	O
Optical	B-Device
Connectors	I-Device
and	O
Jumper	O
Assemblies	O
.	O
</s>
<s>
A	O
multi-fiber	O
optical	B-Device
connector	I-Device
is	O
designed	O
to	O
simultaneously	O
join	O
multiple	O
optical	B-Architecture
fibers	I-Architecture
together	O
,	O
with	O
each	O
optical	B-Architecture
fiber	I-Architecture
being	O
joined	O
to	O
only	O
one	O
other	O
optical	B-Architecture
fiber	I-Architecture
.	O
</s>
<s>
The	O
latter	O
joins	O
one	O
optical	B-Architecture
fiber	I-Architecture
to	O
two	O
or	O
more	O
other	O
optical	B-Architecture
fibers	I-Architecture
.	O
</s>
<s>
Multi-fiber	O
optical	B-Device
connectors	I-Device
are	O
designed	O
to	O
be	O
used	O
wherever	O
quick	O
and/or	O
repetitive	O
connects	O
and	O
disconnects	O
of	O
a	O
group	O
of	O
fibers	O
are	O
needed	O
.	O
</s>
<s>
The	O
multi-fiber	O
optical	B-Device
connector	I-Device
can	O
be	O
used	O
in	O
the	O
creation	O
of	O
a	O
low-cost	O
switch	O
for	O
use	O
in	O
fiber	O
optical	O
testing	O
.	O
</s>
<s>
This	O
would	O
reduce	O
the	O
need	O
for	O
field	O
splicing	O
,	O
which	O
could	O
greatly	O
reduce	O
the	O
number	O
of	O
hours	O
necessary	O
for	O
placing	O
an	O
optical	B-Architecture
fiber	I-Architecture
cable	O
in	O
a	O
telecommunications	O
network	O
.	O
</s>
<s>
Industry	O
requirements	O
for	O
multi-fiber	O
optical	B-Device
connectors	I-Device
are	O
covered	O
in	O
,	O
Generic	O
Requirements	O
for	O
Multi-Fiber	O
Optical	B-Device
Connectors	I-Device
.	O
</s>
<s>
In	O
fiber	B-Architecture
optics	I-Architecture
,	O
a	O
quadruply	B-Device
clad	I-Device
fiber	I-Device
is	O
a	O
single-mode	O
optical	B-Architecture
fiber	I-Architecture
that	O
has	O
four	O
claddings	B-Device
.	O
</s>
<s>
Each	O
cladding	B-Device
has	O
a	O
refractive	O
index	O
lower	O
than	O
that	O
of	O
the	O
core	O
.	O
</s>
<s>
A	O
quadruply	B-Device
clad	I-Device
fiber	I-Device
has	O
the	O
advantage	O
of	O
very	O
low	O
macrobending	O
losses	O
.	O
</s>
<s>
It	O
also	O
has	O
two	O
zero-dispersion	O
points	O
,	O
and	O
moderately	O
low	O
dispersion	O
over	O
a	O
wider	O
wavelength	O
range	O
than	O
a	O
singly	O
clad	O
fiber	O
or	O
a	O
doubly	B-Device
clad	I-Device
fiber	I-Device
.	O
</s>
