TELKOM
NIKA
, Vol. 11, No. 10, Octobe
r 2013, pp. 6
105 ~ 6
110
ISSN: 2302-4
046
6105
Re
cei
v
ed Ap
ril 19, 2013; Revi
sed
Jul
y
1
3
, 2013; Acce
pted Jul
y
23,
2013
The Evolution of Dual-Wavelength Dissipative Soliton
in Yb-Doped Fiber Lasers
Yan
y
an Zhang
1
, Qiang Li
2,3
1
Huan
ghe Si
nc
e and T
e
chno
l
o
g
y
Un
iversit
y
,
Z
hengzh
ou, 4
500
63, Ch
ina
2
State Ke
y
La
b
o
rator
y
for Geo
m
echa
nics & D
eep U
n
d
e
rgro
u
nd Eng
i
n
eeri
n
g
,
China U
n
iver
sit
y
of Mini
ng &
T
e
chnolog
y,
Xuzho
u
, Jian
gsu
,
22111
6, Chi
n
a
3
School of Mec
han
ics & Civil
Engi
neer
in
g, Chin
a Univ
er
sit
y
of Mining & T
e
chno
log
y
,
Xuz
hou, Jia
ngs
u,
221
11
6,Chi
n
a
A
b
st
r
a
ct
Dual-w
av
ele
n
g
t
h dissip
a
tio
n
solito
n
(DS) in the al
l-nor
mal-d
i
spersi
on ytter
b
iu
m-d
o
p
ed fib
e
r las
e
r
(YDF
L) is rep
o
r
ted. Usin
g a p
hase-s
h
ift lon
g
peri
od fi
b
e
r gr
ating (PS-
LPF
G
) as an a
ll-fib
e
r format spect
r
a
l
filter in th
e la
ser cavity, sel
f
-starting du
al-
w
av
elen
gth p
u
l
ses ar
e obt
ai
ned
by n
onl
in
ear p
o
lar
i
z
a
ti
o
n
evol
ution
(NPE
). T
he mod
e
-lo
cking
mech
ani
sm
of the A
N
D
i
cavity w
i
th
dif
f
erent
central
wavelengths has
ana
ly
z
e
d. Ex
p
e
ri
ment
al res
u
l
t
s show
that the NPE
to
get
her w
i
th the
PS-LPF
G
play
key roles
in
the
gen
eratio
n of the du
al-w
ave
l
e
ngth,
mea
n
w
h
il
e, a sw
itchable
dual-w
ave
l
e
n
g
t
h mo
de-l
o
cke
d fiber las
e
r ca
n
achi
eve thro
ug
h chan
ge the p
o
lari
z
a
tio
n
of the cavity.
Ke
y
w
ords
:
al
l-
nor
mal-
dis
pers
i
on, fiber l
a
ser,
mod
e
-l
ocked l
a
ser, sw
itchabl
e, multiw
av
ele
ngth.
Copy
right
©
2013 Un
ive
r
sita
s Ah
mad
Dah
l
an
. All rig
h
t
s r
ese
rved
.
1. Introduc
tion
Multi-wavelength fiber lasers have versatile
applications in
clu
d
ing
fiber optic sensi
ng,
instru
mentati
on,
opti
c
al signal pro
c
e
s
sing
an
d e
s
peci
a
lly in t
he d
e
si
gn
of optical divi
sion
multiplexing sys
tems
(WDM) [1-5].
Re
cently, all
-
no
rmal
-di
s
pe
rsio
n
(ANDi) fi
ber l
a
sers have
attracted great in
terest
s
becau
se of their sim
p
le cavities and hi
gher p
u
ls
e energi
es tha
n
soliton o
r
dispersion
-ma
n
a
ged
soliton
[6, 7]. Ho
weve
r, m
o
st of th
e
sp
ectral
filter
s, i
n
the A
NDi
cavity used
so
far, a
r
e th
e
bulk
comp
one
nts
su
ch a
s
interf
eren
ce filters or birefr
ingent filters, which sa
crifice the advantage
s of
all-fibe
r form
at [6]. Özg
ö
ren et al
[8] reporte
d a
sin
g
le wavelen
g
t
h all-fibe
r-fo
r
mat ANDi m
ode-
locked femto
s
e
c
on
d laser
usin
g a pola
r
i
z
ation m
ode
fiber (PMF
) a
s
the Lyot filter. Ho
weve
r, it
did not h
a
ve
the ca
pability
of pro
d
u
c
ing
dual
- or
mult
i-wavel
ength
mode lo
cking
becau
se of t
he
output wavel
ength was de
termine
d
by the length
of the PMF and
spli
ce an
gle. Zhang et al [9]
repo
rted a m
u
lti-wavel
engt
h dissipative
soliton o
peration in an erbi
um-d
ope
d fiber laser b
a
se
d
on semi
conductor
saturabl
e absorbe
r mi
rror (SESAM). Zhu et al [
10] reported a switchable dual-
wavele
ngth a
nd pa
ssively
mode
-lo
c
ked
ANDi Yb-do
ped fibe
r lasers
by nonlin
ear p
o
lari
zati
on
evolution (NP
E
) effect.
In this p
ape
r,
usin
g a
ph
ase-shifted lo
ng
peri
od fibe
r
grating
(PS-L
P
FG) a
s
an
a
ll-fiber-
format sp
ect
r
al filter in the lase
r cavity,
a
self-startin
g
dual-wavele
ngth and m
o
de-lo
cked la
ser is
achi
eved ba
sed o
n
nonl
inear p
o
la
rization evoluti
on (NPE
) effect. The po
sition
s of du
al-
wavele
ngth a
r
e coin
cide
nt very well wit
h
that
of the passba
n
d
s
of the PS-LPFG. The mo
de-
locking m
e
ch
anism
of the
lase
r
syste
m
is illu
st
rat
ed, whi
c
h
exactly analy
s
is the evolutio
nary
pro
c
e
ss of th
e dual-wavel
ength mod
e
-l
ocked Yb
-d
o
ped fiber la
se
r. The pulses
width and p
u
l
s
e
s
energy can
chang
e furthe
r by adjusting
the polari
z
at
i
on state
s
of the wave
plate
s
in the cavity.
2. Experiment Setup
In our
expe
ri
ment, the PS-LPFG
wa
s fa
bricated
usi
n
g a
CO
2
la
se
r
f
o
cu
sed
on
a
Co
rning
HI 10
60
singl
e-mo
de fibe
r.
The
diamete
r
of the
focu
sed
la
ser sp
ot wa
s
~10
0
μ
m, a
-pha
se
shift wa
s introdu
ced at th
e cent
er of the PS-LP
FG.
The pitch of the fabri
c
ate
d
PS-LPFG
wa
s
318
μ
m, and t
he numb
e
r of
grating pe
rio
d
wa
s 70.
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ISSN: 23
02-4
046
TELKOM
NIKA
Vol. 11, No
. 10, Octobe
r 2013 : 610
5 –
6110
6106
1
010
1020
103
0
104
0
1
0
5
0
1
0
6
0
1
070
-1
5
-1
0
-5
0
Tr
ans
mis
s
(dB)
W
a
v
e
l
eng
t
h
(
n
m
)
P
B
2=
1
046
.
7
nm
P
B
1
=
103
3.
7
n
m
Figure 1. Shows the o
u
tput
spe
c
trum of
PS-
LPFG me
asu
r
ed by opt
ical spe
c
trum
analyze
r
(OSA).
We
can
se
e t
hat the two
n
ear-symm
e
tri
c
al
p
a
ssb
and
s (PB
s
) m
e
a
s
ure at 1
033.
7nm for
PB1 and 104
6.7nm for PB
2, respe
c
tively. The two passb
a
n
d
s
will
serve a
s
the
spe
c
tral filter in
the du
al-wav
elength
mod
e
-
locke
d
la
se
r. The full
wi
dth at h
a
lf maxi
mum (FWHM
)
of the
two
PBs
wa
s 7.8nm fo
r PB 1 and 8.3nm for PB 2, resp
ectively.
Figure 2 sho
w
s the config
uration of the
ex
perimental
setup of a dual wavele
ng
th and
passively mo
de-lo
cked Yb
-dop
ed fibe
r
with a PS-L
P
FG as th
e
spe
c
tral filte
r
. The la
se
r was
building
in a
unidirectio
nal
cavity for
se
lf-startin
g op
eration. A
28
cm
pie
c
e of
Yb-do
ped
g
a
in
fiber (6
12 dB
/m abso
r
ptio
n at 976 nm) was pla
c
e
d
after 72.4 m of single
-
mod
e
fiber (SMF). A
4.2 m segm
ent of SMF placed after
the gain fi
be
r to increa
se
the nonline
a
r pha
se
shi
ft
accumul
a
ted
by the expected
mode
st pulse en
ergy.
The pump la
ser
wa
s a 976 nm gratin
g-
stabili
zed la
ser dio
de, whi
c
h delive
r
s u
p
to 530 m
W
to the gai
n fiber throu
gh a wavele
ngth-
division m
u
ltiplexer
(WDM
). Mode
-lo
cki
ng op
er
atio
n
wa
s initiated
and
stabilized by nonli
n
ear
polari
z
atio
n e
v
olution
(NP
E
), whi
c
h
wa
s im
pleme
n
te
d with
q
uarte
r-wave
plate
s
(Q
WP
s),
a h
a
lf-
wave plate (HWP
) and a polariz
in
g beam
s
p
litter
(PBS). The output
of the las
e
r
was
direc
t
ly
from the NPE
rejectio
n po
rt.
Figure 2. Con
f
iguration of a
n
all norm
a
l d
i
spe
r
si
on pa
ssive mode
-lo
c
ked Yb-dop
ed fiber cavity
with a PS-LP
FG as the
sp
ectral filter.
/4,
/2: quarte
r a
nd half wave
plates.
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TELKOM
NIKA
ISSN:
2302-4
046
The Evol
ution
of Dual-Wa
v
elength
Dissi
pative
Soliton
in Yb-Do
ped
Fiber …
(Yan
yan Zh
ang
)
6107
Figure 3. Illustration of the polari
z
atio
n states of
the light in the mode-lo
cked
system. E: electric
vector of the i
nput sig
nal, U and V: the two ort
hog
onal
birefri
nge
nt axes of the optical fiber.
In orde
r to e
x
plain the m
e
ch
ani
sm of t
he dual
-wavelength la
se
r in
the ANDi
system,
firstly, we sta
r
t to analyze
the light tran
smissio
n
of the la
ser
cavit
y
as sho
w
n i
n
Figu
re 3.
θ
1
is
the angl
e bet
wee
n
the p
o
l
a
rization di
re
ction of th
e in
put sig
nal a
n
d
the verti
c
al
birefri
nge
nt a
x
is
U, and
θ
2
is the an
gle b
e
twee
n the
polari
z
atio
n
di
re
ction
of the an
alyze
r
and the
verti
c
al
birefri
nge
nt axis U. Both
θ
1
and
θ
2
can be cha
nge
d by adjusting t
he wave plat
es (q
uarte
r a
n
d
half waveplat
es). The PBS and isolator play the
rol
e
s of both the polari
z
er, transformi
ng
an
arbitrarily pol
arized lig
ht in
to a linea
r on
e, and
the
an
alyzer, int
r
od
ucin
g an i
n
te
nsity dep
end
ent
transmittance
to
obtain pa
ssive mod
e
-l
ocking acti
n
g
as
an a
r
tificial satu
rabl
e
absorb
e
r. T
h
e
s
i
gnal light is linear
polariz
ed after the PBS. Next,
the
λ
/4 transf
o
rm
s the light to an ellipti
cal
polari
z
atio
n
state. The p
o
l
a
rization
stat
e of the
light
rotates a
s
it p
r
opa
gate
s
in
the
cavity due
to
different effects of the self-pha
se mod
u
l
a
ti
on (SPM), cro
s
s-pha
se
modulatio
n (XPM) and group
velocity delay
on two
ortho
gonal
pola
r
ized compo
nen
ts. The a
ngle
of rotation i
s
prop
ortio
nal
to
the light inte
nsity. Therefore, the PBS
can
le
t only
a certain
po
larization to
pass th
rou
g
h
via
adju
s
ting the
λ
/4 and
λ
/2
wave plate
s
i
n
anothe
r en
d. The
co
mbi
nation of waveplate
s
(q
uarter
and half
waveplates), PBS, and isolator acts
as a pol
ari
z
ation-depen
dent loss for
the
wavele
ngth choo
se. The waveplate
s
act
s
as the p
o
lar
i
zat
i
on
cont
r
o
ls (P
C
s
) in t
h
e lase
r sy
st
e
m
.
The tran
smitti
vity T of the structu
r
e can e
x
presse
d as:
)
cos(
2
sin
2
sin
2
1
sin
sin
cos
cos
2
1
2
2
1
2
2
2
1
2
nl
l
T
(1)
W
h
er
e
)
(
2
x
y
l
n
n
L
(2)
1
2
2
cos
3
2
eff
nl
A
LP
n
(3)
l
is the li
nea
r
pha
se
shift resultin
g from
modal
biref
r
i
ngen
ce,
nl
is t
he no
nline
a
r
pha
se shift whose magnitu
de is the su
m of the SPM and XPM contri
bution
s
.
n
x
and n
y
are the
refra
c
tive ind
e
xes of the f
a
st an
d slo
w
axes of
the o
p
tical fibe
r, resp
ectively. L is the le
ngt
h of
the lase
r cavi
ty length.
λ
is the operatin
g wavelen
g
th
, n
2
is the no
nlinea
r (Kerr) coefficient, P is
the instantan
eou
s pea
k po
wer of inp
u
t signal, and A
eff
is the effective fiber core area. From Eq.
(1) we
can
see that th
e
system tra
n
sm
issi
on
dep
en
ds
on th
e lin
ear pha
se
sh
ift due to
mo
dal
birefri
nge
nce,
and the non
linear p
hase shift in
trodu
ced by the nonlinea
r effect
s of SPM and
XPM. The pe
ak tran
smi
ssi
on de
pen
ds o
n
θ
1 and
θ
2.
Whe
n
, both
o
f
them a
r
e e
q
ual to 0
or
π
/2,
the pe
ak tra
n
s
missio
n
can
rea
c
h
100%,
all the
wavel
e
ngth at thi
s
p
o
lari
zation
ca
n pa
ss th
rou
g
h
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ISSN: 23
02-4
046
TELKOM
NIKA
Vol. 11, No
. 10, Octobe
r 2013 : 610
5 –
6110
6108
the cavity; while o
ne
of th
em i
s
π
/2, th
e othe
r
bein
g
0, it
cha
nge
s to 0,
no
light
ca
n
wo
rk in
this
ca
se.
A
ngle
s
θ
1
and
θ
2
are the othe
r different value
s
, the transmittivity of the fiber loop
manifest
s a
s
a trigo
nomet
ric fun
c
tion
of the
o
peratin
g wavelength
and
the in
st
antane
ou
s p
eak
power.
Co
nseque
ntly, the pol
ari
z
atio
n-de
pen
dent
loss of thi
s
system
can tran
slate
into
wavele
ngth-
and int
ensity-depe
ndent l
o
ss. A
s
can
b
e
seen f
r
om
Eq. (1) that t
he tra
n
smittivity
oscillate
s with operating wavele
ngth. By incorpo
r
at
ing wave plat
es and a PB
S into Yb-doped
fiber
ring l
a
ser, pa
ssive
mode l
o
ckin
g
ba
sed
on
NPE can
re
adi
ly implement.
The
pola
r
iza
t
ion
state of the light rotate
s a
s
it prop
agat
es in t
he la
ser cavity. Moreove
r
, owin
g
to birefring
e
nce
chromati
c di
spersi
on, different
wavelengths
will
emerge from
the round tri
p
with different
polari
z
atio
n states. Since
the rou
nd-t
r
i
p
cavity
loss critically de
pend
s on th
e scala
r
pro
duct
betwe
en the
polari
z
atio
ns
of the incide
nt li
ght and the analy
z
er,
only those
wavelength
s
for
whi
c
h the loss is low enough to matc
h t
he available
gain will be laser.
It should
note
that in ou
r la
ser sy
stem
s, the PS-
LPFG
s a
s
the
all-fi
ber filter in th
e cavity,
the filter h
a
ve playe
d
a
very imp
o
rtant
role
in
th
e
wavelength
ch
oice.
Only th
e wavelengt
h
that
can
satisfy th
e pola
r
i
z
ation
of NPE a
nd
durin
g the
pa
ssban
d of the
PS-LPFG
at
the same tim
e
can b
e
laser.
Namely, the
NPE like a
wavele
ngth swee
ping, different
wavele
ngth ca
n be l
a
se
r
by chan
ged t
he cavity’s po
larization. On
ly the
wavele
ngth adju
s
tin
g
by the waveplats trappe
d in
the band of PS-LPFG, the wavelen
g
th
can be outp
u
t. Therefore, by adjusting
the waveplat
es,
the switch
abl
e dual
-wavel
ength of A
NDi fiber la
se
r can al
so b
e
ob
tained tho
ugh
combi
nation
the
NPE and PS-LPFG.
3. Results a
nd Discu
ssi
ons
The NPE te
chniqu
e u
s
ing
for a
c
hieve
the se
lf-sta
rted mod
e
-l
ocking
state of
the fiber
lase
r. The thresh
old of the
mode-l
o
cke
d
out
put wa
s
about 30
0m
W. Wh
en the
pump po
we
r is
increa
sing
ab
ove the th
re
shold, the
du
a
l
-wav
el
ength
mode
-lo
c
ked
can
be
re
adil
y
achi
eved
by
prop
erly adju
s
ting the waveplate
s
.
1020
1040
1060
1080
-2
0
-1
0
0
10
1020
1040
1060
1080
-8
0
-6
0
-4
0
Transmission (dB)
W
a
v
e
l
e
ngt
h (
n
m
)
01
0
1
FW
H
M
=
4
02
ps
Inte
nsit
y (a
.u.)
Intensity
Ti
me
(
n
s
)
Figure 4. Spectrum of the
mode
-lo
c
ked
dual-w
avel
en
gth lase
r and
its com
pari
s
o
n
with the
corre
s
p
ondin
g
transmissio
n spe
c
tru
m
of the
PS-LPFG. Solid line: the spe
c
tru
m
of dual-
wavele
ngth la
ser o
u
tput; da
she
d
line: tra
n
smi
ssi
on sp
ectru
m
of the PS-LPFG. Inset is the
output pul
se.
Figure 4 sho
w
s the spe
c
trum of the mode-
lo
cked d
u
al-wavelen
gth lase
r outpu
t and its
comp
ari
s
o
n
with the
corresp
ondi
ng transmi
ssio
n
spectrum
of th
e PS-LPF
G
.
The
pump
po
wer
wa
s 43
0m
W. The d
ual-wa
v
elength p
a
ssively mode
-l
ocked
output
in the ANDi
Yb-do
ped fi
ber
lase
rs. It
can
be
see
n
tha
t
the output
wavele
ngth
s
of the mo
de-l
o
cked
pul
se
s are
coin
cide
nt
very well wit
h
that of the
passb
and
s of
the PS-LPFG. The wavel
ength
s
of mo
de-lo
cked d
u
al-
wavele
ngth o
u
tput we
re 10
33.6nm a
nd 1
046.6nm
, respectively, co
rrespon
ding to
1033.7n
m an
d
1046.7
n
m of the passba
n
d
s
of the PS-LPFG. The
inset figure is the pulse
sha
p
e
of the mode-
locked
dual
-wavele
ngth
output at an
avera
ge p
o
w
er of 11.1
0
m
W
with a
repetition rate
o
f
2.499M
Hz. T
he full width
at half maximum (F
WHM
)
of
the pulse
width is 4
02p
s. It is show t
hat
there i
s
a
“di
p
” ap
pea
rin
g
in the middl
e
of the
pul
se.
This
ca
n expl
ain that the t
w
o m
ode
-lo
c
ked
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
The Evol
ution
of Dual-Wa
v
elength
Dissi
pative
Soliton
in Yb-Do
ped
Fiber …
(Yan
yan Zh
ang
)
6109
wavelengths have different
dispersi
on
s in the laser cavity, which
will
result in different time del
ay
in the time d
o
main. It sho
u
ld al
so be
mentione
d th
at it is not n
e
ce
ssary to
have di
spe
r
si
on
manag
eme
n
t comp
one
nts
to obtain the
stable m
ode
-l
ocked
output
s in the A
NDi
lase
r, be
cau
s
e
the spe
c
tral filter plays the
key roles in
pulse
sha
p
in
g and stabili
zing mode lo
cking by virtue
o
f
self-a
mplitud
e mod
u
lation
in the
cavity [6-7]. It can b
e
fou
n
d
that the
m
ode-l
o
cke
d
d
ual-
wavele
ngth o
u
tput is very stable a
nd the PS-LPFG a
s
the an all-fi
ber form
at sp
ectral filter in
the
las
e
r c
a
vity is effic
i
enc
y.
1
000
1020
1040
1060
-80
-60
-40
01
0
1
FWH
M
=40
2
p
s
I
n
t
e
nsit
y (
a
.u.)
Intensity (dBm)
W
a
v
e
length (nm)
Ti
m
e
(
n
s
)
(a)
1000
1
020
10
40
106
0
-80
-60
-40
I
n
t
e
n
s
it
y (a.
u.
)
Intensity (dBm)
W
a
v
e
le
ng
th (
n
m
)
1.
4
d
B
T
i
m
e
(n
s)
(b
)
0.
0
0
.
5
0
1
FW
H
M
=3
1
0ps
10
00
1
020
104
0
1
0
6
0
-80
-60
-40
In
tens
ity
(a.
u
.)
0.
0
0
.
5
0
1
FW
HM=
2
8
7ps
Intensit
y (dBm)
Wavel
e
ngth (nm)
4.9d
B
Ti
m
e
(
n
s
)
(c
)
1
000
10
20
1
0
4
0
10
60
10
80
-1
0
0
-8
0
-6
0
-4
0
01
2
0
1
In
t
e
n
s
ity
(a
.u
.)
FW
H
M
=1
.
1
5
n
s
I
n
tensity (dBm)
W
a
vel
engt
h (
n
m
)
(d
)
T
i
me
(
n
m)
Figure 5. Evolution of the spec
trum outp
u
t of mode-lo
cked la
ser o
p
e
ration in
swit
chin
g mode.
Inset are the output pul
se
s corre
s
po
ndin
g
with the out
put spe
c
tra.
Figure 5 sh
o
w
s the evol
ution
of the mod
e
-lo
c
ked outp
u
t working i
n
dual-wavel
en
gth and
swit
cha
b
le m
ode with the
pump po
we
r
of 530m
W. The wavel
engt
h swit
chin
g can be a
c
hiev
ed
by adjustin
g
the polari
z
a
t
ion comp
on
ents (e.g., quarte
r and h
a
lf waveplat
es)
as Fig
u
re 1
discu
ssi
on. F
i
gure
5(a
)
sh
ows the wav
e
length
s
of
mode
-lo
c
ked
dual-wavele
ngth output
were
1033.6
n
m a
n
d
104
6.6nm,
re
spe
c
tively. The
amplit
u
de of the
sp
ectra
pe
aks
have the
sa
me
intensity, corresp
ondi
ng to the output pulse
s with th
e same e
nergy intensity.
By slight cha
nge
the pola
r
izati
on of the ca
vity,
the pola
r
izatio
n controls can intro
duce wavel
e
ngth-d
epe
nd
ent
cavity loss, the sp
ectra p
eak
s of the dual-wavele
n
g
t
h mode-lo
cked are
cha
n
g
ed as sho
w
n
in
Figure 5(b).
We
can
see t
hat the amplit
ude of the
lef
t
peak i
s
1.4d
B highe
r than
the right p
e
a
k
,
corre
s
p
ondin
g
to the o
u
tp
ut pulse e
nergy intens
ity j
u
st reverse,
namely, the
amplitude
of
the
right pea
k is higher tha
n
the left peak.
Continua
lly
to chan
ge the polari
z
atio
n
station of the
cavity, the amplitude bet
wee
n
the two spe
c
tru
m
s
is increa
sin
g
as sh
own in Figure 5 (c). It
sho
u
ld
be
not
ed that
in th
e
Figu
re
5(c) t
here
only
a
si
ngle
pul
se
ou
tput in th
e la
ser, the
“dip” in
the middle of
the pulse disappe
are
d
, du
e to the spe
c
t
r
um am
plitud
e intensity of the left is hig
her
than the rig
h
t one, whi
c
h
resultin
g in th
e pulse en
erg
y
of the left p
eak i
s
so sm
all whi
c
h
can
not
be se
e in the pulse. Con
t
inually adjusting the pol
a
r
izatio
n stati
on of t
he ca
vity, the sing
le
wavele
ngth
mode
-lo
c
ked
is achieved a
s
sh
own in
Fi
gure
5 (d
). It
can b
e
se
en
that full width at
half maximu
m (F
WHM) of
the o
u
tput
sp
ectral
ba
nd
wi
dth is 3.25
ns,
and
the
co
rresp
ondi
ng
pu
lse
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NIKA
Vol. 11, No
. 10, Octobe
r 2013 : 610
5 –
6110
6110
width is 1.1
5
n
s with the
a
v
erage
outpu
t powe
r
ab
o
u
t
42.3mW. From Figu
re 5
we can see t
h
a
t
the NEP like
as an inte
nsit
y-depe
nde
nt loss in the
laser cavity, PS-LPFG as filter, the switch
ab
le
dual-wavel
en
gth pul
se
ca
n be ge
ne
rat
ed by adju
s
ti
ng wave plat
es for
co
ntrol
the wavele
n
g
th
-
depe
ndent lo
ss.
4. Conclusio
n
In sum
m
ary,
a qualitative
prin
ciple
of d
ual-
and
switcha
b
le
wavel
ength A
NDi fi
ber l
a
ser
has
be
en an
alyzed. Using
a
PS-LPFG as an all-fibe
r
format
s
p
ectral filter in the las
e
r
c
a
vity,
self-startin
g stabilize
d
du
al
-wavel
ength
mode
-lo
cki
ng
ope
ration
is achi
eved by NPE
effect.
By
adju
s
ting the
polari
z
atio
n compon
ents in
the cavi
ty, th
e pulses inte
nsity and pul
se wi
dth will
be
cha
nge
d co
rresp
ondi
ng to the polariza
t
ion stati
on of the laser
cavity. The switch
able du
al-
wavele
ngth
mode
-lo
c
ked
fiber la
se
r can al
so b
e
a
c
hieve
d
by chang
e the p
o
lari
zation
of the
c
a
vity.
Referen
ces
[1]
Schla
ger JB, Ka
w
a
nish
i S, and Saru
w
a
t
a
ri
M.
Dual
w
a
ve
l
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u
ls
e ge
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on usi
ng
mode-l
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cke
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erbi
um-do
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T
o
w
n
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h
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n
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al
w
a
v
e
le
ngth
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h
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ode-
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r
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u
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