<s>
For	O
an	O
optical	B-Architecture
fiber	I-Architecture
,	O
a	O
step-index	B-Device
profile	I-Device
is	O
a	O
refractive	O
index	O
profile	O
characterized	O
by	O
a	O
uniform	O
refractive	O
index	O
within	O
the	O
core	O
and	O
a	O
sharp	O
decrease	O
in	O
refractive	O
index	O
at	O
the	O
core-cladding	O
interface	O
so	O
that	O
the	O
cladding	B-Device
is	O
of	O
a	O
lower	O
refractive	O
index	O
.	O
</s>
<s>
The	O
step-index	B-Device
profile	I-Device
corresponds	O
to	O
a	O
power-law	B-Device
index	I-Device
profile	I-Device
with	O
the	O
profile	O
parameter	O
approaching	O
infinity	O
.	O
</s>
<s>
The	O
step-index	B-Device
profile	I-Device
is	O
used	O
in	O
most	O
single-mode	B-Device
fibers	I-Device
and	O
some	O
multimode	B-Device
fibers	I-Device
.	O
</s>
<s>
A	O
step-index	B-Device
fiber	I-Device
is	O
characterized	O
by	O
the	O
core	O
and	O
cladding	B-Device
refractive	O
indices	O
n1	O
and	O
n2	O
and	O
the	O
core	O
and	O
cladding	B-Device
radii	O
a	O
and	O
b	O
.	O
</s>
<s>
Examples	O
of	O
standard	O
core	O
and	O
cladding	B-Device
diameters	O
2a/2b	O
are	O
8/125	O
,	O
50/125	O
,	O
62.5/125	O
,	O
85/125	O
,	O
or	O
100/140	O
(	O
units	O
of	O
µm	O
)	O
.	O
</s>
<s>
Step-index	B-Device
optical	I-Device
fiber	I-Device
is	O
generally	O
made	O
by	O
doping	B-Algorithm
high-purity	O
fused	O
silica	O
glass	O
(	O
SiO2	O
)	O
with	O
different	O
concentrations	O
of	O
materials	O
like	O
titanium	O
,	O
germanium	O
,	O
or	O
boron	O
.	O
</s>
