<s>
The	O
equilibrium	O
mode	O
 [ power ] 	O
distribution	O
of	O
light	O
travelling	O
in	O
an	O
optical	O
waveguide	O
or	O
fiber	B-Architecture
,	O
is	O
the	O
distribution	O
of	O
light	O
that	O
is	O
no	O
longer	O
changing	O
with	O
fibre	O
length	O
or	O
with	O
input	O
modal	O
excitation	O
.	O
</s>
<s>
At	O
propagation	O
distances	O
exceeding	O
the	O
equilibrium	B-Device
length	I-Device
,	O
intramodal	O
pulse	O
distortion	O
increases	O
(	O
bandwidth	O
decreases	O
)	O
as	O
the	O
square	O
root	O
of	O
length	O
.	O
</s>
<s>
The	O
term	O
equilibrium	B-Device
length	I-Device
is	O
sometimes	O
used	O
to	O
describe	O
a	O
stationary	O
mode	O
distribution	O
,	O
which	O
is	O
the	O
length	O
of	O
multi-mode	B-Device
optical	I-Device
fiber	I-Device
necessary	O
to	O
attain	O
a	O
static	O
mode	O
distribution	O
from	O
a	O
specific	O
excitation	O
condition	O
.	O
</s>
<s>
Equilibrium	B-Device
length	I-Device
is	O
,	O
strictly	O
,	O
the	O
longest	O
such	O
length	O
,	O
as	O
would	O
result	O
from	O
a	O
widely	O
variable	O
range	O
of	O
input	O
excitation	O
.	O
</s>
<s>
Other	O
terms	O
for	O
equilibrium	B-Device
length	I-Device
are	O
equilibrium	O
coupling	O
length	O
and	O
equilibrium	B-Device
mode	I-Device
distribution	I-Device
length	O
.	O
</s>
<s>
(	O
Mandrel	B-Device
wrapping	I-Device
is	O
a	O
viable	O
method	O
to	O
artificially	O
create	O
this	O
state	O
.	O
)	O
</s>
