<s>
and	O
is	O
the	O
nominal	O
refractive	O
index	O
as	O
a	O
function	O
of	O
distance	O
from	O
the	O
fiber	O
axis	O
,	O
is	O
the	O
nominal	O
refractive	O
index	O
on	O
axis	O
,	O
is	O
the	O
refractive	O
index	O
of	O
the	O
cladding	B-Device
,	O
which	O
is	O
taken	O
to	O
be	O
homogeneous	O
(	O
)	O
,	O
is	O
the	O
core	O
radius	O
,	O
and	O
is	O
a	O
parameter	O
that	O
defines	O
the	O
shape	O
of	O
the	O
profile	O
.	O
</s>
<s>
For	O
this	O
class	O
of	O
profiles	O
,	O
multimode	B-Device
distortion	I-Device
is	O
smallest	O
when	O
takes	O
a	O
particular	O
value	O
depending	O
on	O
the	O
material	O
used	O
.	O
</s>
<s>
In	O
the	O
limit	B-Algorithm
of	O
infinite	O
,	O
the	O
profile	O
becomes	O
a	O
step-index	B-Device
profile	I-Device
.	O
</s>
