<s>
where	O
g	O
is	O
the	O
profile	O
parameter	O
,	O
and	O
V	O
is	O
the	O
normalized	B-Device
frequency	I-Device
,	O
which	O
must	O
be	O
greater	O
than	O
5	O
for	O
the	O
approximation	O
to	O
be	O
valid	O
.	O
</s>
<s>
For	O
a	O
step-index	B-Device
fiber	I-Device
,	O
the	O
mode	B-Device
volume	I-Device
is	O
given	O
by	O
V2/2	O
.	O
</s>
