<s>
Filling	B-Device
factor	I-Device
,	O
is	O
a	O
quantity	O
measuring	O
the	O
efficiency	O
of	O
absorption	O
of	O
pump	O
in	O
the	O
core	O
of	O
a	O
double-clad	B-Device
fiber	I-Device
.	O
</s>
<s>
The	O
efficiency	O
of	O
absorption	O
of	O
pumping	O
energy	O
in	O
the	O
fiber	O
is	O
an	O
important	O
parameter	O
of	O
a	O
double-clad	B-Device
fiber	I-Device
laser	O
.	O
</s>
<s>
is	O
a	O
dimensionless	O
adjusting	O
parameter	O
,	O
which	O
is	O
sometimes	O
called	O
the	O
"	O
filling	B-Device
factor	I-Device
"	O
;	O
.	O
</s>
<s>
The	O
filling	B-Device
factor	I-Device
may	O
depend	O
on	O
the	O
initial	O
distribution	O
of	O
the	O
pump	O
light	O
,	O
the	O
shape	O
of	O
the	O
cladding	O
,	O
and	O
the	O
position	O
of	O
the	O
core	O
within	O
it	O
.	O
</s>
<s>
The	O
large	O
(	O
close	O
to	O
unity	O
)	O
filling	B-Device
factor	I-Device
is	O
important	O
in	O
double-clad	B-Device
amplifiers	O
;	O
it	O
allows	O
them	O
to	O
reduce	O
the	O
requirements	O
for	O
the	O
brightness	O
of	O
the	O
pump	O
and	O
to	O
reduce	O
the	O
length	O
of	O
the	O
fiber	O
laser	O
.	O
</s>
<s>
Use	O
of	O
the	O
filling	B-Device
factor	I-Device
for	O
the	O
estimate	O
of	O
the	O
efficiency	O
of	O
absorption	O
of	O
the	O
pump	O
in	O
fiber	O
lasers	O
allows	O
quick	O
estimates	O
without	O
performing	O
complicated	O
numerical	O
simulations	O
.	O
</s>
