<s>
In	O
telecommunications	O
,	O
a	O
cutback	B-Device
technique	I-Device
is	O
a	O
destructive	O
technique	O
for	O
determining	O
certain	O
optical	B-Architecture
fiber	I-Architecture
transmission	B-Algorithm
characteristics	I-Algorithm
,	O
such	O
as	O
attenuation	O
and	O
bandwidth	O
.	O
</s>
<s>
The	O
cut	O
should	O
be	O
made	O
to	O
retain	O
1meter	O
or	O
more	O
of	O
the	O
fiber	O
,	O
in	O
order	O
to	O
establish	O
equilibrium	B-Device
mode	I-Device
distribution	I-Device
conditions	O
for	O
the	O
second	O
measurement	O
.	O
</s>
<s>
In	O
a	O
multimode	B-Device
fiber	I-Device
,	O
the	O
lack	O
of	O
an	O
equilibrium	B-Device
mode	I-Device
distribution	I-Device
could	O
introduce	O
errors	O
in	O
the	O
measurement	O
due	O
to	O
output	O
coupling	O
effects	O
.	O
</s>
<s>
In	O
a	O
single-mode	B-Device
fiber	I-Device
,	O
measuring	O
a	O
shorter	O
cutback	O
fiber	O
could	O
result	O
in	O
significant	O
transmission	O
of	O
cladding	O
modes	O
(	O
light	O
carried	O
in	O
the	O
cladding	O
rather	O
than	O
the	O
core	O
of	O
the	O
optical	B-Architecture
fiber	I-Architecture
)	O
,	O
distorting	O
the	O
measurement	O
.	O
</s>
<s>
Using	O
the	O
cutback	B-Device
technique	I-Device
,	O
the	O
power	O
transmitted	O
through	O
a	O
fiber	O
of	O
known	O
length	O
is	O
measured	O
and	O
compared	O
with	O
the	O
same	O
measurement	O
for	O
the	O
same	O
fiber	O
cut	O
to	O
a	O
length	O
of	O
approximately	O
.	O
</s>
<s>
A	O
variation	O
of	O
the	O
cutback	B-Device
technique	I-Device
is	O
the	O
substitution	B-Device
method	I-Device
,	O
in	O
which	O
measurements	O
are	O
made	O
on	O
a	O
full-length	O
of	O
fiber	O
,	O
and	O
then	O
on	O
a	O
short	O
length	O
of	O
fiber	O
having	O
the	O
same	O
characteristics	O
(	O
core	O
size	O
,	O
numerical	O
aperture	O
)	O
,	O
with	O
the	O
results	O
from	O
the	O
short	O
length	O
being	O
subtracted	O
to	O
give	O
the	O
results	O
for	O
the	O
full	O
length	O
.	O
</s>
