santa clara leos june 2007 - ieee web hosting · semiconductor laser basics laser light out p-type...
TRANSCRIPT
IEEE SCV LEOS Chapter Meeting6 June 2007
High Reliability Diode Pump LasersToby StriteManager of High Power Laser Marketing
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION2
Outline
AlGaInAs High Power Diode Lasers basics
Evolution of High Power AlGaInAs LDs
What is a telecom grade diode laser?
Fiber in lasers paradigm shift
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION3
Semiconductor laser basics
LASER LIGHT OUT
P-TYPE
N-TYPE
HEAT OUT
ACTIVE REGION (QW)LIGHT CREATION
HEAT GENERATION
OSCILLATION
MIRRORHIGH REFLECTIVITY
MIRRORLOW REFLECTIVITY
OUT-COUPLE
HEAT SINKEL
ECTR
ONS
HOLE
SCURRENT IN
WAVEGUIDE
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION4
What’s important?
LASER LIGHT OUT
P-TYPE
N-TYPE
HEAT OUT
Quality of active layer material forwavelength control and reliability
Low internaloptical loss
Extremely robust facetpassivation for reliability
HEAT SINK
Low electrical resistance
Low thermalresistance
2D waveguide formation: epitaxial
&pattern / etch / re-grow
CURRENT IN
ELEC
TRO
NS
HOLE
S
vs
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION5
NIR (800 – 1000nm) Diode Laser Sweet Spot
Material Quality– Excellent substrates, MBE/MOCVD– Bi-polar dopability, low optical absorption– Mirror passivation for high optical power density
Low electrical resistance, low optical lossDiode Laser Design– Pseudomorphic InGaAs QW’s– Symmetric heterostructure band offsets– AlGaAs/GaAs index contrast/lattice match
Low threshold, good confinement, wide λ rangeModerate ~1eV Photon Energy
Between Auger and lattice damage thresholds
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION6
High Power Lasers - Key Attribute Space
main attributesoptical powerlasing wavelengthbrightness (number of modes)integration level
POWER
SPEED
BRIGHTNESS
WAVELENGTHPRICE
RELIABILITY
EFFICIENCY
additional metrics• $ / W• reliability• efficiency (electrical to optical)• speed
INTEGRATION LEVEL
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION7
High Power Lasers - Key Attribute : Power
Power = optical watts
– power at required reliability level• power per deployed hour• telco: ~10M-hr MTBF (100 FIT)• industrial: ~250k-hr MTBF (~4000 FIT)
– power per dollar• customers often use multiple components in
single application
– power at required brightness
POWER
100W
10W
1W
0.1W
1kW
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION8
HPL Key Attributes: integration level
BAR: 100W50-200μm wide apertures
10mm x 1~3mm chip10~50 emitters
MULTI MODE: 10W50-200μm wide aperture
0.4mm x 1~3mm chiptrend to better brightness
SINGLE MODE: 1W3μm wide aperture
0.4mm x 1~3mm chipultimate brightness
BRIGHTNESS
INTEGRATIONLEVEL
Multi Mode
Bars
Single Mode
Single Emitters
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION9
High Power Laser Product Segments
single emitters
multi-emitters,
bars
multi-bars, stacks
fiber-coupled
Telecom,Industrial,Modules
non-fiber-coupled
Chip/CarrierWindowed
Bundles,High
Brightness
Bare chips,Submounts,
Coolers
DirectIllumination
RemoteDelivery
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION10
Industrial Diode Laser Eras
Reliability (inception 2003) “$$$’s and *#&%^!!”– DPSS is considered technology of the future (“always has
been, always will be…”)– Diode laser investment focused in telecom– Unreliable, low brightness bars often the only choice
Telecom-grade (2003 ?) “$/Watts”– Telecom migrants disrupt brightness, drive $/Watt– Even low-end bars reliably deliver 10,000hrs– Reliability and $/Watts begin to de-couple
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION11
Third Industrial Diode Era - Efficiency
Diode Efficiency (2005 ?) “still $/Watts”– reliable power is limited by waste heat
T=15C
0
5
10
15
20
25
30
0 5 10 15 20 25 30
Current, A
Pow
er, W pulsed
CW
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION12
Optimizing single-emitter efficiency
Research funded by DARPA SHEDS program promises power conversion efficiency improvements in future fiber laser pumps
Device Efficiency of Similar Structures at 25C, 940nmDashed = Commecially Available Solid Red = SHEDS Design
0
2
4
6
8
10
0 2 4 6 8 10
Drive Current (A)
Out
put P
ower
(W)
30%
40%
50%
60%
70%
80%Pow
er Conv. Eff.
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION13
SHEDS 940 nm Bars – Final Status
>75% Bar Efficiency at 80W and above>69% Stack Efficiency (NIST) to 500W and beyond
Performance of JDSU/SHEDS 80W Bars
0
25
50
75
100
125
150
0 20 40 60 80 100 120
Drive Current (A)
Out
put P
ower
(W)
50%
55%
60%
65%
70%
75%
80%
Power C
onversion Efficiency
SHEDS Performance of Lensed Water Cooled 950nm StackNIST Measured and Calibrated
0
100
200
300
400
500
600
0 20 40 60 80 100Stack Current (A)
Stac
k Po
wer
(W)
50%
60%
70%
80%
PCE
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION14
Fourth Industrial Diode Era - Brightness
Diode Efficiency (2009 (?) - ???) “$/Watts/sterradian”– How useful is our low cost, ultra-reliable, efficient source?
Reliable 980nm pump lasers for telecom operate 25yrs at >50 MW/cm2
Preserve the inherent brightness of diode lasers– Cut out the solid-state middleman
What’s in the box?
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION15
What is a Telecom-Grade Diode Laser?
Operational Excellence and Business Breadth– Large, fully-absorbed fab (ISO-9001 a decade ago, now TL-9000)– High-volume off-shore assembly
Technical and Cost Roadmaps, Extensive Track Record– Platforms, not just products
Predictable, sustained performance– Rigorous NPI, PCN and PDN processes– Reliability understanding surpasses the qualification report
… Confidence and Transparency for the Customer!
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION16
Which data would you prefer to see your supplier present?
0 1000 2000 3000 4000 5000 6000 7000 8000 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Elapsed time (hrs) Elapsed time (hrs)
JDSU is proud to offer both devices to the market…– …but all recently released and future products are tested to failure
Weaknesses of “rose-colored glasses reliability”– No data on robustness (what happens at 1.2x Pop? What happens in
Year Two of deployment?) – How does reliability scale with temperature, power, current (i.e. real
use conditions)?
100um stripe, 808nm20 units, 7500 hoursTested to nominal deployment conditions
100um stripe, 915/940nm20 units, 5000 hoursTested to nearly 2x Iop, 145°C junction temperature
?
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION17
Rigorous Reliability: Multi-cell Test MethodologyParallel lifetests varyingkey parameters:
– Temperature– Optical Power and/or– Drive Current
Reliable AlGaInAs lasers follow:
(Fop, EA, m, n) determined from
best fit of multi-cell data
( )m
op
n
opopjB
Aopj I
IPP
TTkE
FIPTF ⎟⎟⎠
⎞⎜⎜⎝
⎛•⎟
⎟⎠
⎞⎜⎜⎝
⎛•⎟
⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛−−•=
11exp,,
6
6.5 7
7.5 8
8.5 9
9.5
10
10.5
50
70
90
0.0000
0.1000
0.2000
0.3000
0.4000
0.5000
0.6000
0.7000
0.8000
0.9000
1.0000
Normalized Failure Rate
ex-face t Power (W)
Junction Temperature (C)
Example for multicell test designMulti-cell test conditionsIntended deployment condition
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION18
Pre-conditions for applying multi-cell method
Diode technology must be robust– Permits aggressive, highly effective infant failure
screening– Permits multi-cell test to interrogate wide parameter
space without generating new failure modes
Diode technology should have a single dominant failure mode– Single-emitter diode lasers are typically dominated by
time-independent, sudden, catastrophic failure rates (negligible wear-out)
– Permits high quality empirical fitting of reliability model to multi-cell reliability data
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION19
6390 Diode Laser Multi-cell Test Results
Cell # fixture temp., 0Cjunction temp., 0C Power, W Current, A
number of lasers hours device hours Failures
1 92 129 5.2 7 75 5000 3.6E+05 52 55 107 8.4 10 40 5000 1.7E+05 83 70 126 7.8 10 19 5000 8.9E+04 24 85 145 7.0 10 20 5010 9.2E+04 25 55 125 9.5 12 20 5000 5.5E+04 136 70 145 8.5 12 19 5000 5.4E+04 11
total 193 8.3E+05 41
Cells 1/3/5 and 4/6 vary I at constant TjFailure rates increase with current/power
Cells 2/3/4 and 5/6 vary Tj at constant IFailure rates correlate with power, not temperature
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION20
6390 Diode Laser Multi-cell Test Analysis
Maximum likelihood estimate for random exponential failure distribution neglecting current acceleration (m=0)
Key fitting parameters:
MTBF = 690,000hrs (with 60% confidence level) at 6.5W/35°C heatsink temperature
( )n
opopjb
aopj P
PTTk
EFPTF ⎟⎟⎠
⎞⎜⎜⎝
⎛•⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛−−•=
11exp,
FITFn
eVE
op
A
14207.541.0
===
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION21
Multi-cell testing yields a “user’s manual”
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
0 2 4 6 8 10
Power, W
med
ian
life
time,
hrs
6390 Median time-to-failures for different operating conditions
Heatsink temperature,
0C Power,
WMedian
time, hrs
Median time with 60% C.L.,
hrs
Cumulative failures in 1 year
Cumulative failures in 5 years
Cumulative failures in 10 years
Cumulative failures in 25 years
2.6 6.0E+08 3.0E+08 0.0% 0.0% 0.0% 0.0%5.2 9.1E+06 5.4E+06 0.0% 0.2% 0.7% 2.3%6.5 2.1E+06 1.3E+06 0.2% 1.9% 4.4% 11.2%8 5.3E+05 3.5E+05 1.4% 9.2% 16.8% 31.8%
2.6 3.2E+08 1.7E+08 0.0% 0.0% 0.0% 0.0%5.2 4.8E+06 3.0E+06 0.0% 0.6% 1.6% 5.0%6.5 1.1E+06 7.4E+05 0.5% 4.2% 8.7% 19.3%8 2.8E+05 1.9E+05 3.3% 16.2% 26.9% 45.0%
2.6 1.8E+08 9.8E+07 0.0% 0.0% 0.0% 0.0%5.2 2.6E+06 1.8E+06 0.1% 1.4% 3.5% 9.2%6.5 6.1E+05 4.3E+05 1.2% 8.0% 15.1% 29.3%8 1.5E+05 1.1E+05 6.5% 25.5% 38.7% 58.0%
25
35
45
25C35C45C
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION22
Telecom 980nm pump lasers since 1993…
90mW 980nm pumps assembled in Boston fetched $7000
Five chips, several packages, one transfer to China later…– 660mW 980nm pumps sell below $1000– 90mW 980nm pumps cost $300– and 980nm pump vendors are (again) profitable
Over 13yrs, innovation and focused cost-reduction realized– -21% annual price reduction for 90mW part– +15% annual power increase for 980nm pumps– -26% annual $/mW price reduction to the market
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION23
The Story moves to Fiber Laser Pumps
0.1
1.0
10.0
100.0
1992 1994 1996 1998 2000 2002 2004 2006 2008
Year of Introduction
Pow
er (W
)
Commercially available fiber-coupled power from 100um 9xx nm fiber laser pump diodes
14% average annualpower increase
Multi-mode product cycle times have shortened, driving a performance up-tick since the 2004 release of the 5W 6390-L3.
Annual 17.5% (red) power increases enabling 26% annual $/Watt erosion predicts a reliable 35W fiber-coupled diode will sell for $70 in 2016…!!
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION24
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10 12 14 16
Current, A
Pow
er, W
0%
10%
20%
30%
40%
50%
60%
70%
WP
E
639763966380
Fiber Laser Pump Performance over Generations
Consistent power scaling through increased cavity length, design and technology improvements
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION25
Why Fiber Lasers?
Telecom grade diodes and fiber – disrupting the laser industry– Fiber-based Laser SS/Gas Lasers– Modular, spliced Delicate alignments– Service free Disposables– High efficiency (25+%) Low efficiency (few to 10%)– High brightness Inferior brightness
Direct Diode systems are just another fiber laserSolid-state (classic) lasers are adopting fiber
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION26
Telecom Grade Diodes and Fiber in Lasers
Yb-doped Fiber Laser
Direct Diode w/ Fiber Delivery
Green, Yellow, Orange, uv Fiber Lasers
White Super-continuum Fiber Laser
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION27
JDSU FCD-488 Blue Laser
Laser diode FBG PP crystal beam shaping/light loop
TelecomEDFA
© 2006 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION28
Thanks to:Erik Zucker, Victor Rossin, Thomas Kraft and many other JDSU colleagues