Transcript Slide 1

Nortel Networks Institute
University of Waterloo
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High Performance Semiconductor
Optical Amplifiers:
Enabling All-optical Circuits
Simarjeet Singh Saini
Nanophotonics and Integrated Optoelectronics Group
University of Waterloo
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Semiconductor Amplifiers and
Lasers
Power
Intensity
Fabry-Perot (FP) Laser Diode
R ~ 30%
R ~ 30%
Current
Wavelength
Semiconductor Optical Amplifier (SOA)
Intensity
AR
Power
AR
R < 0.1%
R < 0.1%
Current
Wavelength
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Outline
Introduction
SOA performance in DWDM systems
Non-Uniform Current Distribution
SOA as non-linear elements for Optical Logic
Optical Header Recognition and Packet Routing
Monolithic Integration
Conclusion
4
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Introduction to SOAs
•
SOA Chip
•
•
Angled Facet Ridge or Buried Waveguide
AR Coated (R < 10-5)
•
Typical Performance Specifications
•
•
•
•
•
Gain: 10-20 dB
Saturation Output Power (Psat): 9-12 dBm
Noise Figure: 7-9 dB
Polarization Dependent Gain (PDG): 1.0 dB
Gain flatness: 3 dB
20
Iop=600mA
19
18
17
Gain(dB)
16
MAX@1530nm
MIN@1530nm
15
14
13
12
11
10
9
8
-10
-8
-6
-4
-2
0
2
4
6
8
Output Power (dBm)
10
12
14
16
18
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SOA Applications
Optical Switches
Inline amplification
Pre - amplification
Optical Logic
WDM
DEMUX
Post – amplification
(Booster)
Amplifiers in PICs
WDM
MUX
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SOA vs. EDFA
EDFA responds to average power operation in linear or saturated regime possible
EDFA
Ppeak
Pave
SOA responds to peak power pattern dependent loss if operated in saturation
SOA
SOA operated in linear regime no pattern dependent loss
SOA
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8-Channel DWDM
Experiments
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8-Channel Spectrum
SOA#1 Output Spectrumvs.Output Power
8 WDM Channels
45
100 GHz
7.5 dBm SOA Output
40
9 dBm SOA Output
11 dBm SOA Output
35
13 dBm SOA Output
Output Spectrum (dB)
30
25
20
15
FWM Signals
10
5
0
-5
1550
1552
1554
1556
1558
1560
1562
Wavelength (nm)
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10 Gbps Results
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WDM Performance
 Pattern dependence and multi-channel crosstalk effects are eliminated
by operating the SOA in the linear regime
 Increasing Psat is the key for achieving higher SOA linear output power
Gain
3 dB
Linear Operation
2-3dB
3 dB
Optical Output
Pave Ppeak Psat
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Different Active Regions
Active Region
Engineering
Gain, Psat
Comments
Bulk
Very Easy
High, Low
Have low saturation Power
compared to the QW’s
Most of the commercial
SOA’s are Bulk
Alternate
compressive and
tensile strain QW’s
Easy
High, Low
Half the carriers are not
used at one time; NF will be
High
Tensile Strained
QW’s
δ-strained QW’s
Difficult (get the right High but at lower Can be used for S-band; but
not for C- and L-band
balance)
wavelengths (1.5
mm), High
Difficult
Medium, Medium Easy to grow and reproduce
Distortions in carrier
wavefunctions lead to
reduced gain and saturation
power
Large transparency current
increases NF
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δ-Strained Concept
GaAs Delta Layers
(e = -3.7%)
InGaAsP
(l = 1.27 mm)
Ec
2 6 2 6 2
43 A
Ev
52 A
43 A
Lattice
Matched
InGaAs
repeated 6X
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SOA Results: PI
SOA Performance vs Current
26
24
22
Gain
20
18
16
dB
14
12
Psat
10
8
Gain Max @ 1530
6
Gain Max @ 1550
4
Psat Min @ 1550
Psat Min @ 1530
2
Noise Figure
0
200
300
400
500
Iop (mA)
600
700
800
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SOA Results: Polarization
Sensitive
19
Gain (dB)
I @ 500 mA
 @ 1540 nm
0
TEC : 25 C
16
13
10
8
12
16
20
24
Output Power (dBm)
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• Non-uniform Current Distribution
for Improved Device Performance
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Concept
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Approach
 Using vias in contact layer and changing the longitudinal
density, can change local resistance in the device.
 Arbitrary current distributions can be achieved
 No change in processing steps
P-Metal
Contact vias
Dielectric
Isolation
Ridge
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Resistance Measurements
 2 mm long FP lasers
were used to measure
change of resistance
with contact via spacing
 Ridge width was 3.2 mm
 Contact via spacing was
uniformly varied from 4
mm to 50 mm for
different devices
 Contact via diameter
was 2.7 mm
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Effect on Saturation Power
40.00
Standard
4-20 um spacing
4-50 um spacing
Psat = 15.5 dBm
Gain (dB)
35.00
Psat = 17.8 dBm
30.00
Psat = 19.0 dBm
25.00
Psat increases by 3.5 dB
The linearity of the curve also improves
20.00
0.00
5.00
10.00
15.00
20.00
25.00
Output Power (dBm)
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Multi-contact Topology
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16
16
14
14
1.6 dB
12
12
10
10
8
1.0 dB8
6
6
Psat with Via Contact
NF with Via Contact
Psat with Std. Contact
NF with Std. Contact
4
2
Noise Figure (dB)
Saturation Power (dBm)
Performance Improvements
4
2
0
0
0
2
4
6
8
10
12
Package Number
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Noise Figure Improvement
22
20
Top= 25 C
Iop = 500 mA
16
14
12
10
min g @ 1530
max g @ 1530
min g @ 1550
max g @ 1550
8
10
-16 -14 -12 -10 -8
-6
-4
-2
0
2
4
6
8
10
12
14
16
18
20
9
Output Power [dBm]
8
Noise Figure (dB)
Gain [dB]
18
7
6
5
4
3
2
1
0
0
100
200
300
400
500
600
700
Current (mA)
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• SOAs as Non-linear Elements
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Non-linear Effects in SOA
Cross Gain Modulation
Cross Phase Modulation
Four Wave Mixing
Wavelength Conversion
2R/3R Regeneration
Optical Logic: AND, NAND
Optical Switching
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Packet Routing
Output
Address
Decision is
made at each
stage by taking
the
autocorrelation
of header with a
properly
delayed copy of
itself and
thresholding the
result
1 x 2 Space
Switches
000É 01
Slot 8
Slot
1
clock
bit
100É 01
010... 01
Input
110É 01
001... 01
101É 01
011É 01
111É 01
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Address Recognition
Optical Delay
Optical AND
Gates
Electronic
Trigger
Circuit
.
Toward 1 x
2 Space
Switch
Reading the first header bit
Address Bits
Control Bits
Copy of header
Copy of header delayed by 4 bits
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Sagnac Gate for Optical AND
SOA
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Input Bits
32 bits
Input to the gate
1000xxx 00É 0001000xxx 00ÉÉ .
Control bits
Header bits to be detected
Delay aligned to the 5 th bit
Gate was tested for all 8 combinations of address bits
Correlated output should be 1 only when the 5th bit is 1
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Logic Outputs
Intensity (mW)
5th bit correlated output
Input
1000100
3.00
2.00
1.00
0.00
0
0.2
0.4
0.6
0.8
1
0.8
1
Tim e (ns )
Input
1000011
Intensity (mW)
3.00
2.00
1.00
0.00
0
0.2
0.4
0.6
T im e (n s )
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Control Electronics
From Optical
AND gate
THORLAB
D400FC
Modulator
InGaAs
Detector
MINICIRCUITS
ZFBT-4R2GW
Pulse
Research lab
PRL-470B
Pulse
Research lab
PRL-434A
Wideband
Bias Tee
0.1~4200MHz
Line-Driver
Fanout
Buffer
ECL
BNC
6040
Pulse
Generator
MINICIRCUITS
ZFL-500LN
Amplifier
MINICIRCUITS
SBLP-300
Low-Pass
Filter
DC~180MHz
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Output from InGaAs
Detector
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Integration and SOA driver
7V
0V
10ns
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Eye diagrams for Cascaded
SOAs
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Packet Transmission
All SOA’s turned on
One out of 3 SOA’s off
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•
TM
PARC :
A Platform for Monolithic
Integration of Photonics Devices
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Approach
Amplifier
Passive Splitter
Integrated Mach-Zehnder
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Resonantly Coupled Tapers
Top View of Active and Passive Waveguides
Mode Transform Section
Passive Section
Gain Section
Off-resonance region
Mode excited due
to sharp taper
st
1 order
Suprermode
Phase Matching region
2nd order
Suprermode
Transverse view of Active and Passive Waveguides
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Basic PARC Platform
Mode ormation
f
s
n
a
r
T
on
Secti
v
Passi
on
i
t
c
e
eS
tion
c
e
S
Gain
2.5 mm
1.5 mm
0.3 mm
600 mm
50 mm
2.0 mm
50 mm
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Experimental Results
1.0
30 mm
40 mm
80 mm
100 mm
60 mm
simulated lateral farfield
experimental lateral
simulated farfield
experimental data transverse
Light Intensity (AU)
Output Power (mA)
10
5
0
0
50
Current (mA)
100
0.5
0
-90
-60
-30
0
30
60
90
Angle (in degrees)
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3-dB Lossless Splitters
Input Waveguide
S-bend
Waveguides
Mode
Transformation
Mode Expansion
Mode Expansion
Gain Section
Passive Section
Coupling Gain
Section Sectio
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3-dB Lossless Splitters
20
30
Internal Gain (dB)
Signal Gain (dB)
Amplifier 1
Amplifier 2
20
15
10
10
5
0
0
100
Current (mA)
200
0
1490
1500
1510
1520
1530
1540
1550
1560
1570
Wavelength (nm)
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2x2 Crosspoint Switches
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2x2 Crosspoint Switch
0
Modulation (in dB)
Bar
Cross
-10
-20
Wavelenghth = 1570 nm
-30
-40
0
1
2
3
Voltage (V)
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Conclusion
SOA performance continues to improve
Higher saturation power extends linear operating range
Minimal non-linear distortion/crosstalk for ave. output power < Psat – 6 dB
SOA saturation power of 16 dBm with NF less than 6 dB
demonstrated
SOA can allow for all-optical logic
Further Integration of SOA with photonic devices should allow for
highly functional modules
Future:
Low cost application
FTTH
Coarse and D-WDM
Ultra-fast optical signal processing and Integration
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