<s>
A	O
graded-index	B-Device
or	O
gradient-index	B-Device
fiber	I-Device
is	O
an	O
optical	B-Architecture
fiber	I-Architecture
whose	O
core	O
has	O
a	O
refractive	O
index	O
that	O
decreases	O
with	O
increasing	O
radial	O
distance	O
from	O
the	O
optical	O
axis	O
of	O
the	O
fiber	O
.	O
</s>
<s>
The	O
most	O
common	O
refractive	O
index	O
profile	O
for	O
a	O
graded-index	B-Device
fiber	I-Device
is	O
very	O
nearly	O
parabolic	O
.	O
</s>
<s>
The	O
parabolic	O
profile	O
results	O
in	O
continual	O
refocusing	O
of	O
the	O
rays	O
in	O
the	O
core	O
,	O
and	O
minimizes	O
modal	B-Device
dispersion	I-Device
.	O
</s>
<s>
Multi-mode	B-Device
optical	I-Device
fiber	I-Device
can	O
be	O
built	O
with	O
either	O
graded	O
index	O
or	O
step	B-Device
index	I-Device
.	O
</s>
<s>
The	O
advantage	O
of	O
the	O
multi-mode	O
graded	O
index	O
compared	O
to	O
the	O
multi-mode	O
step	B-Device
index	I-Device
is	O
the	O
considerable	O
decrease	O
in	O
modal	B-Device
dispersion	I-Device
.	O
</s>
<s>
Modal	B-Device
dispersion	I-Device
can	O
be	O
further	O
decreased	O
by	O
selecting	O
a	O
smaller	O
core	O
size	O
(	O
less	O
than	O
5	O
–	O
10μm	O
)	O
and	O
forming	O
a	O
single-mode	B-Device
step	I-Device
index	I-Device
fiber	I-Device
.	O
</s>
<s>
is	O
the	O
constant	O
of	O
graded	B-Device
index	I-Device
profile	I-Device
.	O
</s>
