<s>
Multi-mode	B-Device
optical	I-Device
fiber	I-Device
is	O
a	O
type	O
of	O
optical	B-Architecture
fiber	I-Architecture
mostly	O
used	O
for	O
communication	O
over	O
short	O
distances	O
,	O
such	O
as	O
within	O
a	O
building	O
or	O
on	O
a	O
campus	O
.	O
</s>
<s>
Multi-mode	B-Device
fiber	I-Device
has	O
a	O
fairly	O
large	O
core	B-Device
diameter	I-Device
that	O
enables	O
multiple	O
light	O
modes	O
to	O
be	O
propagated	O
and	O
limits	O
the	O
maximum	O
length	O
of	O
a	O
transmission	O
link	O
because	O
of	O
modal	B-Device
dispersion	I-Device
.	O
</s>
<s>
The	O
standard	O
G.651.1	O
defines	O
the	O
most	O
widely	O
used	O
forms	O
of	O
multi-mode	B-Device
optical	I-Device
fiber	I-Device
.	O
</s>
<s>
The	O
equipment	O
used	O
for	O
communications	O
over	O
multi-mode	B-Device
optical	I-Device
fiber	I-Device
is	O
less	O
expensive	O
than	O
that	O
for	O
single-mode	B-Device
optical	I-Device
fiber	I-Device
.	O
</s>
<s>
Because	O
of	O
its	O
high	O
capacity	O
and	O
reliability	O
,	O
multi-mode	B-Device
optical	I-Device
fiber	I-Device
generally	O
is	O
used	O
for	O
backbone	O
applications	O
in	O
buildings	O
.	O
</s>
<s>
Standards-compliant	O
architectures	O
such	O
as	O
Centralized	O
Cabling	O
and	O
fiber	B-Protocol
to	I-Protocol
the	I-Protocol
telecom	I-Protocol
enclosure	I-Protocol
offer	O
users	O
the	O
ability	O
to	O
leverage	O
the	O
distance	O
capabilities	O
of	O
fiber	O
by	O
centralizing	O
electronics	O
in	O
telecommunications	O
rooms	O
,	O
rather	O
than	O
having	O
active	O
electronics	O
on	O
each	O
floor	O
.	O
</s>
<s>
Multi-mode	B-Device
fiber	I-Device
is	O
used	O
for	O
transporting	O
light	O
signals	O
to	O
and	O
from	O
miniature	O
fiber	B-Architecture
optic	I-Architecture
spectroscopy	O
equipment	O
(	O
spectrometers	O
,	O
sources	O
,	O
and	O
sampling	O
accessories	O
)	O
and	O
was	O
instrumental	O
in	O
the	O
development	O
of	O
the	O
first	O
portable	O
spectrometer	O
.	O
</s>
<s>
Multi-mode	B-Device
fiber	I-Device
is	O
also	O
used	O
when	O
high	O
optical	O
powers	O
are	O
to	O
be	O
carried	O
through	O
an	O
optical	B-Architecture
fiber	I-Architecture
,	O
such	O
as	O
in	O
laser	O
welding	O
.	O
</s>
<s>
The	O
main	O
difference	O
between	O
multi-mode	O
and	O
single-mode	B-Device
optical	I-Device
fiber	I-Device
is	O
that	O
the	O
former	O
has	O
much	O
larger	O
core	B-Device
diameter	I-Device
,	O
typically	O
50	O
–	O
100	O
micrometers	O
;	O
much	O
larger	O
than	O
the	O
wavelength	O
of	O
the	O
light	O
carried	O
in	O
it	O
.	O
</s>
<s>
Because	O
of	O
the	O
large	O
core	B-Device
and	O
also	O
the	O
possibility	O
of	O
large	O
numerical	O
aperture	O
,	O
multi-mode	B-Device
fiber	I-Device
has	O
higher	O
"	O
light-gathering	O
"	O
capacity	O
than	O
single-mode	B-Device
fiber	I-Device
.	O
</s>
<s>
In	O
practical	O
terms	O
,	O
the	O
larger	O
core	B-Device
size	O
simplifies	O
connections	O
and	O
also	O
allows	O
the	O
use	O
of	O
lower-cost	O
electronics	O
such	O
as	O
light-emitting	O
diodes	O
(	O
LEDs	O
)	O
and	O
vertical-cavity	O
surface-emitting	O
lasers	O
(	O
VCSELs	O
)	O
which	O
operate	O
at	O
the	O
850nm	O
and	O
1300nm	O
wavelength	O
(	O
single-mode	B-Device
fibers	I-Device
used	O
in	O
telecommunications	O
typically	O
operate	O
at	O
1310	O
or	O
1550nm	O
)	O
.	O
</s>
<s>
However	O
,	O
compared	O
to	O
single-mode	B-Device
fibers	I-Device
,	O
the	O
multi-mode	B-Device
fiber	I-Device
bandwidth	O
–	O
distance	O
product	O
limit	O
is	O
lower	O
.	O
</s>
<s>
Because	O
multi-mode	B-Device
fiber	I-Device
has	O
a	O
larger	O
core-size	O
than	O
single-mode	B-Device
fiber	I-Device
,	O
it	O
supports	O
more	O
than	O
one	O
propagation	O
mode	O
;	O
hence	O
it	O
is	O
limited	O
by	O
modal	B-Device
dispersion	I-Device
,	O
while	O
single	O
mode	O
is	O
not	O
.	O
</s>
<s>
The	O
LED	O
light	O
sources	O
sometimes	O
used	O
with	O
multi-mode	B-Device
fiber	I-Device
produce	O
a	O
range	O
of	O
wavelengths	O
and	O
these	O
each	O
propagate	O
at	O
different	O
speeds	O
.	O
</s>
<s>
This	O
chromatic	O
dispersion	O
is	O
another	O
limit	O
to	O
the	O
useful	O
length	O
for	O
multi-mode	B-Device
fiber	I-Device
optic	O
cable	O
.	O
</s>
<s>
In	O
contrast	O
,	O
the	O
lasers	O
used	O
to	O
drive	O
single-mode	B-Device
fibers	I-Device
produce	O
coherent	O
light	O
of	O
a	O
single	O
wavelength	O
.	O
</s>
<s>
Because	O
of	O
the	O
modal	B-Device
dispersion	I-Device
,	O
multi-mode	B-Device
fiber	I-Device
has	O
higher	O
pulse	O
spreading	O
rates	O
than	O
single	B-Device
mode	I-Device
fiber	I-Device
,	O
limiting	O
multi-mode	B-Device
fiber	I-Device
's	O
information	O
transmission	O
capacity	O
.	O
</s>
<s>
Single-mode	B-Device
fibers	I-Device
are	O
often	O
used	O
in	O
high-precision	O
scientific	O
research	O
because	O
restricting	O
the	O
light	O
to	O
only	O
one	O
propagation	O
mode	O
allows	O
it	O
to	O
be	O
focused	O
to	O
an	O
intense	O
,	O
diffraction-limited	O
spot	O
.	O
</s>
<s>
The	O
standard	O
TIA-598C	O
recommends	O
,	O
for	O
non-military	O
applications	O
,	O
the	O
use	O
of	O
a	O
yellow	O
jacket	O
for	O
single-mode	B-Device
fiber	I-Device
,	O
and	O
orange	O
or	O
aqua	O
for	O
multi-mode	B-Device
fiber	I-Device
,	O
depending	O
on	O
type	O
.	O
</s>
<s>
Some	O
vendors	O
use	O
violet	O
to	O
distinguish	O
higher	O
performance	O
OM4	B-Device
communications	O
fiber	O
from	O
other	O
types	O
.	O
</s>
<s>
Multi-mode	B-Device
fibers	I-Device
are	O
described	O
by	O
their	O
core	B-Device
and	O
cladding	B-Device
diameters	O
.	O
</s>
<s>
Thus	O
,	O
62.5/125μm	O
multi-mode	B-Device
fiber	I-Device
has	O
a	O
core	B-Device
size	O
of	O
62.5	O
micrometres	O
( μm	O
)	O
and	O
a	O
cladding	B-Device
diameter	O
of	O
125μm	O
.	O
</s>
<s>
The	O
transition	O
between	O
the	O
core	B-Device
and	O
cladding	B-Device
can	O
be	O
sharp	O
,	O
which	O
is	O
called	O
a	O
step-index	B-Device
profile	I-Device
,	O
or	O
a	O
gradual	O
transition	O
,	O
which	O
is	O
called	O
a	O
graded-index	B-Device
profile	I-Device
.	O
</s>
<s>
Multi-mode	B-Device
fibers	I-Device
may	O
be	O
constructed	O
with	O
either	O
graded	B-Device
or	O
step-index	B-Device
profile	I-Device
.	O
</s>
<s>
In	O
addition	O
,	O
multi-mode	B-Device
fibers	I-Device
are	O
described	O
using	O
a	O
system	O
of	O
classification	O
determined	O
by	O
the	O
ISO	O
11801	O
standard	O
—	O
OM1	O
,	O
OM2	O
,	O
and	O
OM3	O
—	O
which	O
is	O
based	O
on	O
the	O
modal	O
bandwidth	O
of	O
the	O
multi-mode	B-Device
fiber	I-Device
.	O
</s>
<s>
OM4	B-Device
(	O
defined	O
in	O
TIA-492-AAAD	O
)	O
was	O
finalized	O
in	O
August	O
2009	O
,	O
and	O
was	O
published	O
by	O
the	O
end	O
of	O
2009	O
by	O
the	O
TIA	O
.	O
</s>
<s>
OM4	B-Device
cable	O
will	O
support	O
125m	O
links	O
at	O
40	O
and	O
100	O
Gbit/s	O
.	O
</s>
<s>
For	O
many	O
years	O
62.5/125μm	O
(	O
OM1	O
)	O
and	O
conventional	O
50/125μm	O
multi-mode	B-Device
fiber	I-Device
(	O
OM2	O
)	O
were	O
widely	O
deployed	O
in	O
premises	O
applications	O
.	O
</s>
<s>
These	O
fibers	O
easily	O
support	O
applications	O
ranging	O
from	O
Ethernet	O
(	O
10Mbit/s	O
)	O
to	O
gigabit	O
Ethernet	O
(	O
1Gbit/s	O
)	O
and	O
,	O
because	O
of	O
their	O
relatively	O
large	O
core	B-Device
size	O
,	O
were	O
ideal	O
for	O
use	O
with	O
LED	O
transmitters	O
.	O
</s>
<s>
Newer	O
deployments	O
often	O
use	O
laser-optimized	O
50/125μm	O
multi-mode	B-Device
fiber	I-Device
(	O
OM3	O
)	O
.	O
</s>
<s>
Optical	B-Architecture
fiber	I-Architecture
manufacturers	O
have	O
greatly	O
refined	O
their	O
manufacturing	O
process	O
since	O
that	O
standard	O
was	O
issued	O
and	O
cables	O
can	O
be	O
made	O
that	O
support	O
10	O
GbE	O
up	O
to	O
400	O
meters	O
.	O
</s>
<s>
Laser	O
optimized	O
multi-mode	B-Device
fiber	I-Device
(	O
LOMMF	O
)	O
is	O
designed	O
for	O
use	O
with	O
850nm	O
VCSELs	O
.	O
</s>
<s>
400GBASE-SR4.2	O
)	O
use	O
wavelength-division	B-Architecture
multiplexing	I-Architecture
(	O
WDM	B-Architecture
)	O
even	O
for	O
multi-mode	B-Device
fiber	I-Device
which	O
is	O
outside	O
the	O
specification	O
for	O
OM4	B-Device
and	O
lower	O
.	O
</s>
<s>
In	O
2017	O
,	O
OM5	O
has	O
been	O
standardized	O
by	O
TIA	O
and	O
ISO	O
for	O
WDM	B-Architecture
MMF	O
,	O
specifying	O
not	O
only	O
a	O
minimum	O
modal	O
bandwidth	O
for	O
850nm	O
but	O
a	O
curve	O
spanning	O
from	O
850	O
to	O
953nm	O
.	O
</s>
<s>
Cables	O
can	O
sometimes	O
be	O
distinguished	O
by	O
jacket	O
color	O
:	O
for	O
62.5/125μm	O
(	O
OM1	O
)	O
and	O
50/125μm	O
(	O
OM2	O
)	O
,	O
orange	O
jackets	O
are	O
recommended	O
,	O
while	O
aqua	O
is	O
recommended	O
for	O
50/125μm	O
"	O
laser	O
optimized	O
"	O
OM3	O
and	O
OM4	B-Device
fiber	O
.	O
</s>
<s>
Some	O
fiber	O
vendors	O
use	O
violet	O
for	O
"	O
OM4+	O
"	O
.	O
</s>
<s>
VCSEL	O
power	O
profiles	O
,	O
along	O
with	O
variations	O
in	O
fiber	O
uniformity	O
,	O
can	O
cause	O
modal	B-Device
dispersion	I-Device
which	O
is	O
measured	O
by	O
differential	O
modal	O
delay	O
(	O
DMD	O
)	O
.	O
</s>
<s>
Modal	B-Device
dispersion	I-Device
is	O
caused	O
by	O
the	O
different	O
speeds	O
of	O
the	O
individual	O
modes	O
in	O
a	O
light	O
pulse	O
.	O
</s>
<s>
The	O
greater	O
the	O
length	O
,	O
the	O
greater	O
the	O
modal	B-Device
dispersion	I-Device
.	O
</s>
<s>
To	O
combat	O
modal	B-Device
dispersion	I-Device
,	O
LOMMF	O
is	O
manufactured	O
in	O
a	O
way	O
that	O
eliminates	O
variations	O
in	O
the	O
fiber	O
which	O
could	O
affect	O
the	O
speed	O
that	O
a	O
light	O
pulse	O
can	O
travel	O
.	O
</s>
<s>
The	O
IEC	O
61280-4-1	O
(	O
now	O
TIA-526-14-B	O
)	O
standard	O
defines	O
encircled	O
flux	O
which	O
specifies	O
test	O
light	O
injection	O
sizes	O
(	O
for	O
various	O
fiber	O
diameters	O
)	O
to	O
make	O
sure	O
the	O
fiber	B-Device
core	I-Device
is	O
not	O
over-filled	O
or	O
under-filled	O
to	O
allow	O
more	O
reproducible	O
(	O
and	O
less	O
variable	O
)	O
link-loss	O
measurements	O
.	O
</s>
