IEEE Communications Society Chapter Meeting February 17, 1998 Optical Communications Technology for Free Space and Guided Wave Systems Dr. Mark Wickert, [email protected] Communications and Signal Processing Group Electrical and Computer Engineering Department University of Colorado at Colorado Springs Colorado Springs, Colorado 80933-7150 February 17, 1998
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IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Opt
ical
Com
mun
icat
ions
Te
chno
logy
for
Fr
ee S
pace
and
Gui
ded
Wav
e S
yste
ms
Dr.
Mar
k W
icke
rt, w
icke
rt@
sign
al.u
ccs.
edu
Com
mun
icat
ions
and
Sig
nal P
roce
ssin
g G
roup
Ele
ctri
cal a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f C
olor
ado
at C
olor
ado
Spri
ngs
Col
orad
o Sp
ring
s, C
olor
ado
8093
3-71
50
Febr
uary
17,
199
8
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
2
Ove
rvie
w
•C
omm
unic
atio
n sy
stem
s ov
ervi
ew
•A
bri
ef h
isto
ry o
f op
tical
com
mun
icat
ions
•O
ptic
al v
s. R
F an
d C
oppe
r
•Sy
stem
s th
eory
vie
w o
f op
tical
com
mun
icat
ions
•A
pplic
atio
n E
xam
ples
—G
uide
d-w
ave/
fibe
r
—Fr
ee s
pace
dir
ecte
d an
d no
n-di
rect
ed (
diff
use)
•T
he f
utur
e
—A
ll op
tical
net
wor
ks, i
nclu
ding
sw
itchi
ng
—W
irel
ess
netw
orke
d cl
assr
oom
s an
d m
eetin
g ro
oms
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
3
Fo
rms
of
Co
mm
un
icat
ion
Sys
tem
s
Th
e el
ectr
om
agn
etic
sp
ectr
um
Mes
sage
Sour
ceM
essa
geSi
nkR
ecei
ver
Cha
nnel
Tra
ns-
mitt
er
Wav
elen
gth-
λ
Freq
uenc
y-H
z10
310
410
510
610
710
910
1010
1410
1510
1110
8
105
104
103
102
101
101–
102–
106–
100
800–
2550
nm
Optica
l Fibe
rs
mm-Wav
es
SHF
UHF
VHF
HF
MF
LF
VLF
Audio
AM Radio
VHF TV/
FM R
adio Cell Pho
nes PCS
Sat. C
omm.
LORAN
Human
Hearin
g
IE
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C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
4
So
me
His
tory
•T
he i
nven
tion
of t
he l
aser
in
abou
t 19
60 f
orm
s th
e st
art-
ing
poin
t for
opt
ical
com
mun
icat
ions
res
earc
h
•In
the
ear
ly 1
960’
s fr
ee s
pace
opt
ical
com
mun
icat
ions
rese
arch
sta
rted
1
•O
ne o
f th
e m
ore
sign
ific
ant
mili
tary
pro
gram
s w
as t
heA
ir F
orce
405
B p
rogr
am w
hich
set
out
to d
evel
op s
pace
-qu
alif
ied
lase
r co
mm
unic
atio
ns h
ardw
are
—T
he s
yste
m w
as f
light
tes
ted
in t
he l
ate
1970
’s a
t th
eW
hite
San
ds M
issi
le R
ange
1.S
. Lam
bert
and
W. C
asey
, Las
er C
omm
unic
atio
ns in
Spa
ce, A
rtec
h H
ouse
, Bos
ton,
199
5
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
5
His
tory
(co
nt.
)
—T
he s
yste
m u
sed
a ne
odym
ium
yit
triu
m a
lum
inum
gar
-ne
t (N
D:Y
AG
) la
ser
doub
led
from
inf
rare
d to
gre
enlig
ht,
with
a
dire
ct
dete
ctio
n re
ceiv
er
(PM
T’s
an
dA
PD’s
)
—T
he n
omin
al b
it ra
te w
as 1
Gb/
s w
ith s
lant
ran
ges
up t
o10
0 km
—Fo
llow
on
proj
ects
incl
ude
sate
llite
cro
ss li
nks
and
sate
l-lit
e to
sub
mar
ine
links
usi
ng b
lue-
gree
n la
sers
—D
evel
opm
ent i
n th
is a
rea
is n
ow n
on-e
xist
ent
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
6
Fib
er H
isto
ry
•W
ork
in o
ptic
al f
iber
s w
aveg
uide
s be
gan
at a
bout
the
sam
e tim
e
•In
itial
ly lo
sses
wer
e on
the
orde
r of
100
0 dB
/km
•T
he v
iabi
lity
of o
ptic
al w
aveg
uide
s ca
me
in 1
970
atC
orni
ng G
lass
Wor
ks, w
here
a s
ilica
fibe
r w
ith 2
0 dB
/km
of lo
ss w
as f
abri
cate
d
•D
urin
g th
e ne
xt tw
o de
cade
s th
e lo
ss w
as d
rive
n do
wn
toa
mer
e 0.
16 d
B/k
m a
t 155
0 nm
IE
EE
C
om
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ni
ca
ti
on
s
So
ci
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Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
7
Fiv
e G
ener
atio
ns
of
Fib
er P
rog
ress
1
1974
1976
1978
1980
1982
1984
1986
1988
1990
0.1
1.010100
1000
System Performance (Gb/s x km)
Yea
r
1550
nm
sing
le-m
ode
cohe
rent
det
ecti
on
1550
nm
, sin
gle-
mod
edi
rect
det
ecti
on
1300
nm
sing
le-m
ode
800
nmm
ulti
mod
e
Erb
ium
-dop
edfi
ber
ampl
ifie
rsat
155
0 nm
1.G
erd
Kei
ser,
Opt
ical
Fib
er C
omm
unic
atio
ns, s
econ
d ed
itio
n, M
cGra
w H
ill,
New
Yor
k, 1
991.
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
8
Lo
w A
tten
uat
ion
Win
do
ws1
Attenuation (dB/km)
Wav
elen
gth
(nm
)Ear
ly 1
970’
s
1980
’s
Seco
ndW
indo
wT
hird
Win
dow
Fir
stW
indo
w10
0
50 20 10 5.0
2.0
1.0
0.5
0.2
0.1
600
800
1000
1200
1400
1600
1800
1.G
erd
Kei
ser,
Opt
ical
Fib
er C
omm
unic
atio
ns, s
econ
d ed
itio
n, M
cGra
w H
ill,
New
Yor
k, 1
991.
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
9
Tech
no
logy
Dev
elo
pm
ent1
Gen
erat
ion
Lig
ht
Sour
cea
a.L
D =
lase
r di
ode;
DFB
= d
istr
ibut
ed f
eedb
ack
lase
r; D
BR
= d
istr
ibut
ed B
ragg
ref
lect
ion
lase
r
Wav
elen
gth
(nm
)
Fib
er
Att
enua
tion
(dB
/km
)
Fib
er
Dis
pers
ion
Det
ecti
on
Fir
stG
aAs
LD
Fabr
y-P
erot
(F
B)
LD
800–
900
>5
Lar
ge
(mul
tim
ode)
Dir
ect
Sec
ond
FP
LD
1300
1 at
1330
nm
very
sm
all
(sin
gle-
mod
e fi
ber)
Dir
ect
Thi
rdD
FB L
D13
00 a
nd
1550
0.2
at 1
550
very
sm
all a
t 13
30D
irec
t
Four
thD
FB a
nd
DB
R L
D13
00 a
nd
1550
0.2
at 1
550
0.5
at 1
300
Dis
pers
ion
shif
ted
for
zero
at 1
550
Coh
eren
t
Fif
thD
FB
and
D
BR
LD
1300
and
15
50O
ptic
al
ampl
ifie
rsO
ptic
al s
oli-
tons
Dir
ect a
nd
cohe
rent
1.M
ax M
ing-
Kan
g L
iu, P
rinc
iple
s an
d A
ppli
cati
ons
of O
ptic
al C
omm
unic
atio
ns, I
rwin
, Chi
cago
,IL
, 199
6.
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
10
Co
st H
isto
ry1
Communications costs ($/1000 mi/mo/kb/s)Computing costs ($/10 kips)10
6
105
104
103
102
10 119
7019
7419
7819
8219
8619
9019
9419
98
Subs
crib
erC
osts
Fib
erT
runk
s
Com
puti
ng
1.Pa
ul G
reen
, Fib
er O
ptic
Net
wor
ks, P
rent
ice
Hal
l, E
ngle
woo
d C
liff
s, N
ew J
erse
y, 1
993.
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
11
Th
e S
tate
-of-
the
Art
Jan
uar
y 19
961
Wav
elen
gth
div
isio
n m
ult
iple
xin
g (
WD
M)
•A
T&
T B
ell
Lab
s de
mon
stra
ted
a sy
stem
tra
nsm
ittin
gei
ght
5 G
b/s
WD
M c
hann
els
over
an
equi
vale
nt d
ista
nce
of 9
000
km (
dist
ance
acr
oss
the
Paci
fic)
•In
a la
ter
expe
rim
ent t
wen
ty 5
Gb/
s ch
anne
ls w
ere
tran
s-m
itted
ove
r a
dist
ance
of
6300
km
(0.
1 T
b/s
tran
scon
ti-ne
ntal
)
1.T.
Bel
l, J.
Ada
m, a
nd S
. Low
e, “
Tech
nolo
gy 1
996–
Com
mun
icat
ions
,” I
EE
E S
pect
rum
, pp.
30–
41,
Janu
ary
1996
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
12
Sta
te-o
f-th
e A
rt (
con
t.)
Dis
per
sio
n-c
om
pen
sati
ng
fib
er•
Ord
inar
y fi
bers
lim
it hi
gh c
apac
ity o
ver
long
dis
tanc
es b
yth
e fi
ber’
s ch
rom
atic
dis
pers
ion
and
nonl
inea
ritie
s
•A
chr
omat
ic d
ispe
rsio
n co
mpe
nsat
ing
fibe
r at
155
0 nm
,w
hich
is
the
win
dow
of
low
est
atte
nuat
ion
for
sing
le-
mod
e fi
bers
, was
dev
elop
ed
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
13
Sta
te-o
f-th
e A
rt (
con
t.)
So
lito
ns
•A
n al
tern
ativ
e to
com
pens
ated
fib
ers
is th
e us
e of
sol
iton
light
pul
ses
whi
ch s
tay
in s
hape
tem
pora
lly a
nd s
pec-
tral
ly a
s th
ey p
ropa
gate
thro
ugh
an o
rdin
ary
fibe
r
•T
his
grou
p of
res
earc
hers
, al
so f
rom
AT
&T
Bel
l L
abs,
dem
onst
rate
d tr
ansm
issi
on o
f ei
ght
5 G
b/s
WD
M c
han-
nels
ove
r 90
00 k
m
•A
n ad
ded
feat
ure
of th
e so
liton
pul
ses
is th
at th
ey m
ay b
esp
aced
clo
ser
in w
avel
engt
h (0
.2 n
m)
than
tha
t of
the
othe
r B
ell L
ab’s
gro
up
•A
pot
entia
l dra
wba
ck to
sol
itons
is p
ower
con
sum
ptio
n
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
14
Op
tica
l vs.
RF
an
d C
op
per
Adv
anta
ges
Ove
r R
F S
yste
ms
•T
rem
endo
us i
ncre
ase
in t
he m
odul
atio
n ba
ndw
idth
and
henc
e th
e ov
eral
l inf
orm
atio
n ba
ndw
idth
•O
n th
e su
rfac
e th
e us
able
ban
dwid
th o
f op
tical
sys
tem
s is
abou
t fi
ve o
rder
s of
mag
nitu
de l
arge
r th
an t
hat
avai
labl
eto
an
RF
carr
ier;
25,
000
GH
z of
BW
in e
ach
optic
al b
and
•Fr
ee s
pace
opt
ical
sys
tem
s al
so p
rovi
de s
ecur
ity a
ndin
terf
eren
ce im
mun
ity s
ince
ver
y na
rrow
bea
mw
idth
s ar
epo
ssib
le
•D
ue t
o th
e sm
all
wav
elen
gths
inv
olve
d, o
ptic
al c
ompo
-ne
nts
are
very
sm
all
in c
ompa
riso
n w
ith R
F/m
icro
wav
eco
mpo
nent
s
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
15
Op
tica
l vs.
RF
an
d C
op
per
(co
nt.
)
•Fi
ber
spec
ific
fe
atur
es
incl
ude:
sm
all
size
an
d lig
htw
eigh
t, el
ectr
ical
iso
latio
n, a
nd a
n ab
unda
nce
of r
awm
ater
ials
(sa
nd f
or m
akin
g gl
ass)
Dis
adva
nta
ges
Ove
r R
F S
yste
ms
•O
ptic
al f
requ
enci
es h
ave
diff
eren
t pro
paga
tion
char
acte
r-is
tics
than
RF
freq
uenc
ies,
thus
the
desi
gn te
chni
ques
are
muc
h di
ffer
ent
—T
radi
tiona
l R
F co
mm
unic
atio
n sy
stem
s en
gine
ers
sim
-pl
y ne
ed to
be
educ
ated
on
thes
e is
sues
•T
he n
arro
w b
eam
wid
ths
alth
ough
goo
d fo
r se
curi
ty a
ndpo
wer
eff
icie
ncy,
req
uire
ver
y ac
cura
te a
lignm
ent
of f
ree
spac
e be
ams
and
accu
rate
cou
plin
g in
fib
er s
yste
ms
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
16
Op
tica
l Co
mm
un
icat
ion
s P
yram
id1
App
licat
ions
Net
wor
ks: v
oice
,vi
deo,
CA
TV
,L
AN
, WL
AN
Syst
ems:
tran
smit
ters
,re
ceiv
ers,
poin
t-to
-poi
nt li
nks
Com
pone
nts:
LE
Ds,
lase
rs,
fibe
rs,
phot
odet
ecto
rs
Mat
eria
ls
1.L
eoni
d K
azov
sky,
Ser
gio
Ben
edet
to, a
nd A
lan
Wil
lner
, Opt
ical
Fib
er C
omm
unic
atio
n S
yste
ms,
Art
ech
Hou
se, N
orw
ood,
MA
, 199
6.
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
17
Gu
ided
-Wav
e (O
pti
cal F
iber
) S
yste
ms
•Fi
ber
syst
ems
may
be
eith
er a
nalo
g or
dig
ital
Inte
nsi
ty M
od
ula
ted
An
alo
g S
yste
ms
•W
ith
inte
nsity
m
odul
atio
n (I
M)
the
info
rmat
ion
isdi
rect
ly m
odul
ated
ont
o th
e op
tical
car
rier
. As
an a
ltern
a-tiv
e w
e m
ay w
ish
to u
se a
rad
io f
requ
ency
(R
F) s
ubca
r-ri
er
Sub
carr
ier
Mod
ulat
or
Lase
r w
ithIn
tens
ityM
odul
ator
SC
M/IM
Lig
ht
Fie
ld
Pho
toD
etec
tor/
Rec
eive
r
Sub
carr
ier
Rec
over
yB
P F
ilter
Sub
carr
ier
Dem
od
Mes
sag
e
dt()
mt()
yt()
zt()
d̂t()
SNR
d
SNR
sc
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
18
Gu
ided
Wav
e S
yste
ms
(co
nt.
)
•R
easo
ns f
or c
hoos
ing
this
SC
M/I
M s
chem
e ar
e:
—To
im
prov
e th
e de
mod
ulat
ed S
NR
via
non
linea
r m
odu-
latio
n, e
.g.,
freq
uenc
y m
odul
atio
n (F
M)
—To
allo
w m
ultip
le s
ubca
rrie
rs e
ach
carr
ying
a d
iffe
rent
info
rmat
ion
sour
ce (
subc
arri
er m
ultip
lexi
ng)
Driv
e C
urre
nt
Output Light Intensity
I s
mt()
I sβm
t()
Las
er D
iod
e w
ith
In
ten
sity
Mo
du
lati
on
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
19
Gu
ided
Wav
e S
yste
ms
(co
nt.
)
Dig
ital
Sys
tem
s•
Dig
ital s
yste
ms
may
impl
emen
t:
—In
tens
ity
mod
ulat
ion
with
ba
seba
nd
dire
ct
dete
ctio
n(I
M/D
D)
—In
tens
ity m
odul
atio
n us
ing
subc
arri
ers
—C
oher
ent m
odul
atio
n an
d de
mod
ulat
ion
•T
he m
ost c
omm
on I
M/D
D s
chem
e is
on-
off
keyi
ng
0
1D
ata
Inp
ut
I sO
N
OF
F0
Tb
Lig
ht
Ou
tpu
t
t
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
20
Dir
ect
Det
ecti
on
Rec
eive
r M
od
el
•Si
gnal
-to-
nois
e ra
tio (
SNR
)
Ps
1βm
t()
+[
]P
b+
Det
ecto
rw
ith g
ain
αg
Hω(
)S
ign
al
αg2
Ps
Pb
+(
)I dc e------
Sh
ot
No
ise
Dar
kN
0c
Cu
rren
t
Pos
tD
etec
tF
ilter
it()
yt()
Th
erm
alN
ois
eP
ho
toD
etec
tor
Pho
to-
Det
ecto
r
yt()
2πB
m–
2πB
m
S mω(
)
Mea
sure
SN
R H
ere
ω
1F
ω()
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
21
Fre
e S
pac
e S
yste
ms
Dir
ecte
d a
nd
No
n-D
irec
ted
•D
irec
ted
links
can
be
used
in s
atel
lite
cros
slin
ks, a
nd c
anbe
use
d to
net
wor
k bu
ildin
gs in
a c
ampu
s
•H
ere
the
fiel
d of
vie
w (
FOV
) of
bot
h th
e re
ceiv
er a
ndtr
ansm
itter
is v
ery
narr
ow
•A
hou
seho
ld e
xam
ple
of a
non
-dir
ecte
d lin
k is
the
rem
ote
cont
rol u
sed
for
TV
and
aud
io s
yste
ms
•In
an
trul
y di
ffus
e lin
k th
e op
tical
pow
er i
s sc
atte
red
abou
t a r
oom
by
the
wal
ls, c
eilin
g, f
loor
, and
fur
nitu
re
•A
qua
si-d
iffu
se s
chem
e w
here
the
‘ba
se s
tatio
n’ h
asbr
oad
cove
rage
and
the
rem
ote
stat
ions
are
lin
e-of
-sig
htis
als
o po
ssib
le
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
22
Fre
e S
pac
e E
xam
ple
:W
irel
ess
Lo
cal A
rea
Net
wo
rk1
Wir
eles
s Te
rmin
als
Dif
fuse
Acc
ess
Nod
es
Net
wor
kSe
rver
Peer
-to-
Peer
Net
wor
king
1.Jo
seph
Kah
n, J
ohn
Bar
ry,
et.a
l., “
Non
-Dir
ecte
d In
frar
ed L
inks
for
Hig
h-C
apac
ity W
irel
ess
LA
Ns,
” IE
EE
Per
sona
l Com
mun
icat
ions
, sec
ond
quar
ter
1994
, pp.
12–
25.
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
23
Gu
ided
Wav
e E
xam
ple
: W
DM
Fib
er-
Bas
ed O
pti
cal N
etw
ork
s
•C
reat
e a
mul
tiple
acc
ess
netw
ork
usin
g tim
e di
visi
onm
ultip
le a
cces
s (T
DM
A)
(or
TD
M t
ime
divi
sion
mul
ti-pl
exin
g)
and
wav
elen
gth
divi
sion
m
ultip
le
acce
ss(W
DM
A)
(or
WD
M w
avel
engt
h di
visi
on m
ultip
lexi
ng)
•T
he n
etw
ork
itsel
f re
quir
es a
lar
ge i
nter
conn
ectio
n of
man
y op
tical
fib
er p
aths
•L
oss
asso
ciat
ed w
ith s
igna
l sp
littin
g ca
n be
miti
gate
dus
ing
phot
onic
am
plif
iers
•In
the
fut
ure
phot
onic
sw
itchi
ng w
ill a
void
the
nee
d to
conv
ert t
o el
ectr
ical
sig
nals
and
bac
k to
opt
ical
aga
in
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
24
WD
M O
pti
cal N
etw
ork
s (c
on
t.)
•A
rec
ent
artic
le b
y R
yan1 d
iscu
sses
WD
M d
eplo
ymen
tan
d th
e fu
ture
of
true
opt
ical
net
wor
king
usi
ng o
ptic
alsw
itche
s
1.Jo
hn R
yan,
“W
DM
: Nor
th A
mer
ican
Dep
loym
ent T
rend
s,”
IEE
E C
omm
unic
atio
ns M
agaz
ine,
vol
.36
, no.
2, F
eb. 1
998,
pp.
40–
44.
1994
1995
1996
1997
1998
100 050 1040 30 2060708090
Gb/s
WD
M &
TD
M
TD
M O
nly
•M
axim
um
tran
smis
sion
ra
te u
sing
co
mm
erci
ally
av
aila
ble
hard
war
e
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
25
Fre
e S
pac
e E
xam
ple
: P
oin
t-to
-Po
int
•H
igh
spee
d da
ta l
inks
bet
wee
n bu
ildin
gs u
sing
dir
ecte
dbe
ams
•A
com
mer
cial
ven
dor,
Silc
om, h
as a
pro
duct
lin
e kn
own
as F
rees
pace
and
Fre
espa
ce T
urbo
for
wir
eles
s bu
ildin
g-to
-bui
ldin
g ne
twor
king
•Fe
atur
es:
—D
ista
nces
up
to 1
000
ft. (
300
m)
with
99.
9% a
vaila
bilit
y
—Fr
eesp
ace:
ful
l dup
lex
10 M
bps
Eth
erne
t
—Fr
eesp
aceT
urbo
: 44
Mbp
s E
ther
net t
o 15
0 M
bps
AT
M
—M
icro
wav
e be
twee
n 1
GH
z an
d 10
0 G
Hz
can
prov
ide
10M
bps
Eth
erne
t at a
max
imum
ran
ge o
f 1
km
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
26
Co
ncl
usi
on
s
•T
he t
echn
olog
y be
hind
tod
ay’s
opt
ical
com
mun
icat
ions
is
inde
ed
inte
rest
ing,
an
d m
ay
even
be
co
nsid
ered
extr
aord
inar
y
•O
ptic
al c
omm
unic
atio
ns h
as m
ade
grea
t pr
ogre
ss i
n its
rela
tivel
y sh
ort ~
30 y
ear
hist
ory
•O
ne a
utho
r st
ates
tha
t th
e pr
ogre
ss i
n op
tical
fib
er c
om-
mun
icat
ions
tec
hnol
ogy
is r
ival
ed o
nly
by t
he f
ield
of
com
pute
rs
•Q
uest
ions
rem
ain:
—A
s co
nsum
ers
whe
n w
ill w
e ha
ve f
iber
in th
e ho
me?
—W
ill o
ptic
al w
irel
ess
LA
Ns
prov
ide
any
com
petit
ion
into
day’
s R
F w
irel
ess
revo
lutio
n?
IE
EE
C
om
mu
ni
ca
ti
on
s
So
ci
et
y
Ch
ap
te
r
Me
et
in
g
Fe
br
ua
ry
1
7,
1
99
8
Dr.
Mar
k W
icke
rt–O
ptic
al T
echn
olog
y fo
r Fr
ee-S
pace
and
Gui
ded-
Wav
e S
yste
ms
Ele
ctric
al a
nd C
ompu
ter
Eng
inee
ring
Dep
artm
ent
Uni
vers
ity o
f Col
orad
o at
Col
orad
o S
prin
gsC
olor
ado
Spr
ings
, Col
orad
o 80
933-
7150
27
Ref
eren
ces
[1]
John
Bar
ry, W
irel
ess
Infr
ared
Com
mun
icat
ions
, Klu
wer
Aca
dem
ic P
ublis
h-er
s, B
osto
n, M
A, 1
994.
[2]
Rob
ert
M. G
aglia
rdi
and
Sher
man
Kar
p, O
ptic
al C
omm
unic
atio
ns, s
econ
ded
ition
, Joh
n W
iley,
New
Yor
k, 1
995.
[3]
Paul
Gre
en,
Fib
er O
ptic
Net
wor
ks,
Pren
tice
Hal
l, E
ngle
woo
d C
liffs
, N
ewJe
rsey
, 199
3.
[4]
Jose
ph K
ahn,
Joh
n B
arry
, et
.al.,
“N
on-D
irec
ted
Infr
ared
Lin
ks f
or H
igh-
Cap
acity
Wir
eles
s L
AN
s,”
IEE
E P
erso
nal C
omm
unic
atio
ns, s
econ
d qu
arte
r19
94, p
p. 1
2–25
.
[5]
Leo
nid
Kaz
ovsk
y, S
ergi
o B
ened
etto
, and
Ala
n W
illne
r, O
ptic
al F
iber
Com
-m
unic
atio
n Sy
stem
s, A
rtec
h H
ouse
, Nor
woo
d, M
A, 1
996.
[6]
Ger
d K
eise
r, O
ptic
al F
iber
Com
mun
icat
ions
, sec
ond
editi
on, M
cGra
w H
ill,
New
Yor
k, 1
991.
[7]
Max
Min
g-K
ang
Liu
, Pri
ncip
les
and
App
lica
tion
s of
Opt
ical
Com
mun
ica-
tion
s, I
rwin
, Chi
cago
, IL
, 199
6.
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