5/19/2006cipi workshop on fiber lasers l r chen multi-wavelength semiconductor fiber lasers lawrence...
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5/19/2006CIPI Workshop on Fiber LasersL R Chen
Multi-wavelength Semiconductor Fiber Lasers
Lawrence R. ChenPhotonic Systems Group
Department of Electrical and Computer EngineeringMcGill University
Montreal, Quebec, [email protected]
5/19/2006CIPI Workshop on Fiber LasersL R Chen
Acknowledgments
• Reuven E. Gordon, Véronique Pagé, Dr. Varghese Baby
• Serge Doucet, Prof. Sophie LaRochelle
• NSERC Canada and Canadian Institute for Photonic Innovations
• Anritsu Electronics, Ltd.
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Multi-wavelength optical sources have numerous applications:– Optical instrumentation– Fiber optic sensing– Optical communications– Microwave photonics
• Regimes of operation– Continuous wave– Mode-locked
• Fiber-based solutions are attractive and have the advantage of low coupling loss to optical fiber systems
Motivation
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Stable operation– Power– Wavelength
• Broad wavelength range• Wavelength spacing from very large (100’s of GHz) to very
narrow (10’s of GHz)• High output power (mW)• Single longitudinal mode• Tunable operation
Features
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Stable, multi-wavelength operation with narrow wavelength spacing is difficult to achieve in erbium-doped fiber (EDF) due to homogeneous broadening– Cool to 77 K– Frequency-shifting– Polarization holeburning– Careful gain equalization – Complex cavities
• Semiconductor optical amplifiers exhibit inhomogeneous linewidth broadening
Challenges
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Use SOAs as the gain medium
• Ring or standing-wave cavities
• Multi-wavelength filters– Ideally, fiber-based such as:
Fiber Bragg gratings Mach-Zehnder interferometers
• Tunable multi-wavelength operation– Tunable wavelength filters (lasing wavelengths are
individually tunable)– Tunable comb filters (lasing wavelengths have equally
increased or decreased wavelength spacing)
Semiconductor Fiber Lasers
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• First demonstration of a multi-wavelength semiconductor fiber ring laser– Serial SOAs used to increase lasing bandwidth
SFL with a Fabry-Pérot Filter
N. Pleros et al, IEEE PTL, vol. 14, pp. 693-695 (2002)
38 wavelengths with 50 GHz channel spacing
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• First demonstration of multi-wavelength lasing in a ring laser using a sampled FBG
SFL with Sampled FBG
J. Sun et al, IEEE PTL, vol. 14, pp. 750-752 (2002)
nP2
2
Sampled FBG: periodic comb filterwith wavelength spacing set by thesample period P
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Switchable operation demonstrated with a sampled FBG in HiBi fiber
SFL with Sampled FBG in HiBi Fiber
B.-A. Yu et al, IEE EL, vol. 39, pp. 649-650 (2003)
yx nn 2
Due to the different effective indices of the x and y polarizations in the HiBi fiber, each polarization will have its own reflection peak
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• > 40 wavelengths with 0.5 nm spacing and tunable operation– VOA used to control lasing wavelengths by saturating
the SOA
SFL with a Mach-Zehnder Interferometer
F. W. Tong et al, IEE EL, vol. 40, pp. 594-595 (2004)
VOA = 3 dB
, nm, nm
VOA = 8.5 dBVOA = 14 dB
, nm
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• 75 wavelengths with 40 GHz spacing
SFL with a PLC-BasedDelayed Interferometer
DI spectral responseLaser output
increasingcavityloss
H. Dong et al, IEEE PTL, vol. 17, pp. 303-305 (2005)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• 50 wavelengths with 50 GHz spacing at 1300 nm
SFL with a Fabry-Pérot Filter
H. Chen, Opt Lett, vol. 30, pp. 619-621 (2005)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• LOA (gain-clamped SOA)– Reduced transients compared to conventional SOA
which results in improved power stability
SFL with a Linear Optical Amplifier
K. K. Kureshi, IEEE PTL, vol. 17, pp. 1611-1613 (2005)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• 20 wavelengths with 100 GHz spacing using multi-wavelength thin film etalon filter
SFL with a Linear Optical Amplifier
Sample laser output
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Comparison of power stability
SFL with a Linear Optical Amplifier
LOA SOA
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Fiber loop mirror incorporating a segment of HiBi fiber– Coupler splits input beam into two counter-propagating
beams and recombines them after traveling through fiber loop
– Birefringence (n) produces a phase difference () between the fast and slow components of a propagating beam
HiBi Fiber Loop Mirror Comb Filter
Fang and Claus, Opt Lett, vol. 20, pp. 2146-2148 (1995)Dong et al., Electron. Lett., vol. 36, pp. 1609-1610 (2000)
PC1
HiBi, L
3 dBcoupler
in
out
• Reflectivity of FLM depends on this phase difference:
where • Periodicity given by
cos121
)( R
/2 nL
nL
2
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Interleaved waveband switching• 17 wavelengths with 100 GHz spacing, bands separated
by 50 GHz
SFL with HiBi-FLM
Y. W. Lee et al, IEEE PTL, vol. 16, pp. 54-56 (2004)
Comb filter responseLaser output response
5/19/2006CIPI Workshop on Fiber LasersL R Chen
Digitally Programmable HiBi-FLM
L. R. Chen, IEEE PTL, vol. 16, pp. 410-412 (2004)
• State of the switches determines the total length of HiBi fiber in the FLM– If the HiBi fiber segments have equal lengths L, the
total length can be varied digitally between L, 2L, … NL– Thus, the wavelength separation can also vary digitally
between
…
PC1
HiBi, L1
PC2
HiBi, L2
PCN
HiBi, LN
22 switch3 dBcoupler
combinerin
out
nLNnLnL
222
,,2
,
• As a simple demonstration, we use two fiber segments and one switch– For the cross-state,
– For the bar state,
PC1
HiBi, LPC2
HiBi, L
22 switch3 dBcoupler
combinerin
out
nL
2
nL
2
2
5/19/2006CIPI Workshop on Fiber LasersL R Chen
Digitally Programmable HiBi-FLM
1535 1540 1545 1550 1555 1560 1565-60
-40
-20
contrast > 20 dB = 3.2 nm
Ref
lect
ivity
, dB
Wavelength, nm
Switch in cross-state• L = 1.99 m 3.2 nm• insertion loss 7 dB
1535 1540 1545 1550 1555 1560 1565-90
-80
-70
-60
-50
contrast > 15 dB = 1.6 nm
Ref
lect
ivity
, dB
Wavelength, nm
Switch in bar state• L = 3.98 m 1.6 nm• insertion loss 10 dB
After changing the state of theswitch, may need to adjust PC to optimize contrast
• Results
5/19/2006CIPI Workshop on Fiber LasersL R Chen
1540 1550 1560 1570 1580 1590 1600-80
-70
-60
-50
-40
-30
-20
-10
P = < 5 dB
Out
put p
ower
, dB
m
Wavelength, nm
Tunable SFL
• Switch in cross-state
• 6 lasing wavelengths with minimum SNR = 40 dB• linewidths < 0.12 nm
• Switch in bar-state
• 11 lasing wavelengths with minimum SNR = 36 dB• linewidths < 0.15 nm
1540 1550 1560 1570 1580 1590 1600-80
-70
-60
-50
-40
-30
-20
-10
P = < 8.5 dB
Out
put p
ower
, dB
m
Wavelength, nm
5/19/2006CIPI Workshop on Fiber LasersL R Chen
1562 1564 1566 1568 1570 1572
Wavelength, nmin
tens
ity, 1
0 dB
/div
Tunable SFL
• Stability: repeated scans of output spectra
Output power fluctuations < 1.5 dBWavelength variations < 0.05 nm
1560 1565 1570 1575 1580
Wavelength, nm
inte
nsity
, 10
dB/d
iv
Switch in cross-state ( = 3.2 nm) Switch in bar state ( = 1.6 nm)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
Waveband-Switchable SFL
M. P. Fok et al, IEEE PTL, vol. 17, pp. 1393-1395 (2005)
• Phase modulator in HiBi-FLM allows tuning of the comb filter transfer function– Used to vary amount of birefringence in the loop– Shift in comb response but comb spacing is unchanged
• 21 wavelengths with 100 GHz spacing
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Increased wavelength range of operation
SFL with HiBi-FLMand Hybrid SOA-EDFA Gain Medium
Y.-G. Han et al, IEEE PTL, vol. 17, pp. 989-991 (2005)
Tunable wavelength spacingTunable wavelengths
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Superimposed chirped FBGs can be used to create a high-finesse FP resonator (CFPR)
FBG-Based Fabry-Pérot
R. Slavík et al, IEEE PTL, vol. 16, pp. 1017-1019 (2004)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Standing-wave cavity
SOA
PC C/L Coupler
FBG
10:90
Output
50:50
OSA
PC
HiBiFiber
1548 1552 1556 1560 1564 1568-24
-20
-16
-12
-8
-4
Wavelength (nm)
Tra
nsm
issi
on
(d
B)
Grating Transmission
SFL with a CFPR
V. Baby et al, CIPI Project IT2
FSR = 25 GHz
5/19/2006CIPI Workshop on Fiber LasersL R Chen
1545 1550 1555 1560 1565 1570-60
-40
-20
0
1545 1550 1555 1560 1565 1570-60
-40
-20
0
Variation of Laser with 23nm HiBi Filter, using Polarization Control
1545 1550 1555 1560 1565 1570-60
-40
-20
0
1545 1550 1555 1560 1565 1570-60
-40
-20
0
1545 1550 1555 1560 1565 1570-60
-40
-20
0
1545 1550 1555 1560 1565 1570-60
-40
-20
0O
utp
ut P
ow
er
(dB
m)
Wavelength (nm)Wavelength (nm)
Ou
tpu
t Po
we
r (d
Bm
)
Wavelength (nm)
Ou
tpu
t Po
we
r (d
Bm
)
Wavelength (nm)
Ou
tpu
t Po
we
r (d
Bm
)O
utp
ut P
ow
er
(dB
m)
Wavelength (nm)
Ou
tpu
t Po
we
r (d
Bm
)
Wavelength (nm)
• Tunable operation by adjusting PC in HiBi-FLM
SFL with a CFP Resonator
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• 35 wavelengths with 25 GHz spacing
1548 1552 1556 1560 1564 1568-60
-50
-40
-30
-20
-10
0
Wavelength (nm)
Ou
tpu
t Po
we
r (d
Bm
)Laser Spectrum using 23nm HiBi Filter
SFL with a CFP Resonator
9 dB
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Photonic code conversion in packet-switched networks with code-based processing (CIPI Project IT2)
Application of Multi-wavelength SFL
Code Contention System
Switch
Contention Resolution
(Label switching)
R. E. Gordon and L. R. Chen, IEEE PTL, vol. 18, pp. 586-588 (2006)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
Photonic Code Conversion: Schematic and Principle
PC1
SOA1 SOA2
AWG
λj1 λj2 λj3 λj4
Output Code j
10%
90%PC2
VOA
TLS1
TLS2
TLS3
TLS4
4
x
1
MOD EDFA
Isolator
λi1λi2λi3λi4
Loop Mirrors
OCA
OCB
CONTROL ARM
RING
Input Code i
PCC
PD Rx
SAT
OFF
ON
5/19/2006CIPI Workshop on Fiber LasersL R Chen
PC1
SOA1 SOA2
AWG
λj1 λj2 λj3 λj4
Output Code j
10%
90%PC2
VOA
TLS1
TLS2
TLS3
TLS4
4
x
1
MOD EDFA
Isolator
λi1λi2λi3λi4
Loop Mirrors
OCA
OCB
CONTROL ARM
RING
Input Code i
PCC
PD Rx
UNSAT
ON
OFF
Photonic Code Conversion: Schematic and Principle
5/19/2006CIPI Workshop on Fiber LasersL R Chen
PCC Results
-70
-60
-50
-40
-30
-20
-10
1532 1534 1536 1538 1540 1542 1544
Input Code
Output Code
Wavelength (nm)
Pow
er
(dB
m)
λi
1
λi
2
λi3 λi
4
λj1 λj2 λj3 λj4 PCC setup:
ISOA,1 = 36mAISOA,2 = 139mA
-60
-55
-50
-45
-40
-35
-30
-25
-12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2
Total Input Power (dBm)
Peak O
utp
ut
Pow
er
(dB
m)
Static Response Summary:
• 4.7dB Input swing
• 23.3dB Output swing
• Sharp, step-like transition
• Thresholding and limiting functionality
• 2R regeneration possible
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Measuring chromatic dispersion based on time-of-flight
V. Pagé and L. R. Chen, Opt Commun (to appear, 2006)
Applications of Tunable Multi-wavelength SFL
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Measurements using both wavelength spacings
Measuring CD based on TOF: Results
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• CD measurements for both wavelength spacings and comparison to standard phase-shift technique
Measuring CD based on TOF: Results
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Tunable photonic microwave filter
L. R. Chen and V. Pagé, IEE EL, vol. 41, pp. 1183-1184 (2005)
multi-optical source
RF out
electro-opticmodulator
dispersivemedium
SMF
fRF
lightwave componentanalyzer
EDFA
N
mRFm
RFRF DfmjP
fc
DfH
1
220 1exp
2cos
DFSR
1
Applications of Tunable Multi-wavelength SFL
0 2 4 6-50
-40
-30
-20
-10
0
no
rma
lize
d fi
lter
resp
on
se, d
B
frequency, GHz
0 2 4 6-50
-40
-30
-20
-10
0
= 3.2 nm
= 1.6 nm
• Microwave filter response (using 9.5 km of SMF as dispersive medium)
5/19/2006CIPI Workshop on Fiber LasersL R Chen
• Using SOA as a gain medium allows for:– Stable, multi-wavelength operation at room
temperature– Narrow wavelength spacings (25 GHz demonstrated)– Relatively simply implementation
• Issues for further study:– Power equalization– Single longitudinal mode operation
Summary