Namkyoo Park Nanoscale Energy Conversion and Information Processing Devices
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Transcript of Namkyoo Park Nanoscale Energy Conversion and Information Processing Devices
Next Generation Optical Amplifiers Next Generation Optical Amplifiers
requirements, bottlenecks, possible resolutionsrequirements, bottlenecks, possible resolutions
(Approach concerned on Cost, Footprint , Functionality(Approach concerned on Cost, Footprint , Functionalityrather than Efficiency, utilizing nano-photonics)rather than Efficiency, utilizing nano-photonics)
Namkyoo Park
Nanoscale Energy Conversion and Information Processing DevicesSeptember 24 th, 2006
Photonic Systems LaboratorySchool of EE, Seoul National University
http://[email protected]
Photonic Systems Lab School of EECS, S.N.U.
Photonic Systems Lab School of EECS, S.N.U.
Research Topics in PSL : Research Topics in PSL : PastPast / Present / Present
Photon Generation Raman Amplifier Erbium Amplifier Thulium Amplifier nano-Photonics : Er / Raman based Si Amplifier / Laser) This presentation
Photon Transport Transient control & amplified transmission line design Polarization Mode Dispersion tolerant transmission format Multi-level Optical Transmission
Photon Control – Coding, Detection, Logic Optical Coding (CDMA, Noise reduction) Super-resolution Techniques (2D / 3D Imaging) Surveillance system for FTTH network Distributed / Multi-port Temperature sensor Semiconductor Amplifier & SOA based Logic Gates
Integration with / Applications to IT, BT & NT Tunable Optical devices (including Photonic Crystals, MEMS) Application to Medical-Photonics (3-D Tomography)
Photonic Systems Lab School of EECS, S.N.U.
The First MileThe First MileThe First MileThe First Mile
BackboneBackbone Continent to Continent Continent to Continent Coast to Coast all over Coast to Coast all over
Fiber at 10 Gbps & upFiber at 10 Gbps & up
BackboneBackbone Continent to Continent Continent to Continent Coast to Coast all over Coast to Coast all over
Fiber at 10 Gbps & upFiber at 10 Gbps & up
MetroMetro City to City-Town to Town City to City-Town to Town all over Fiber all over Fiber at 1Gbps 10 Gbpsat 1Gbps 10 Gbps
MetroMetro City to City-Town to Town City to City-Town to Town all over Fiber all over Fiber at 1Gbps 10 Gbpsat 1Gbps 10 Gbps
AccessAccess To the optically Fibered To the optically Fibered World “First Mile / Last Mile” World “First Mile / Last Mile” 56kbps 1 Gbps56kbps 1 Gbps
AccessAccess To the optically Fibered To the optically Fibered World “First Mile / Last Mile” World “First Mile / Last Mile” 56kbps 1 Gbps56kbps 1 Gbps
LANLAN Desktop to Desktop – Desktop to Desktop – Floor to Floor Floor to Floor 10 Mbps 1 Gbps10 Mbps 1 Gbps
LANLAN Desktop to Desktop – Desktop to Desktop – Floor to Floor Floor to Floor 10 Mbps 1 Gbps10 Mbps 1 Gbps Jonathan Thatcher, OFC2002, Tutorial Sessions(2002)Jonathan Thatcher, OFC2002, Tutorial Sessions(2002)
Network Evolution – Market Calls for METRO and BelowNetwork Evolution – Market Calls for METRO and Below
Long Haul More of the same (higher speed, more wavelength, longer reach…)
Metro/Access will shape the next wave of innovative components Tunable, intelligent, distributed amplification
The “siliconization” of photonics Drive scalable manufacturing and cost efficiency Push optics further into the network and ensure sustainable growth of the industry
Photonic Systems Lab School of EECS, S.N.U.
Network Evolution – Challenges in TechnologyNetwork Evolution – Challenges in Technology
OITDA2000
Photonic Systems Lab School of EECS, S.N.U.
Network Evolution – Challenges : Met for METRO netwoNetwork Evolution – Challenges : Met for METRO networkrk
Now in the Market ! (2002)Now in the Market ! (2002)
Photonic Systems Lab School of EECS, S.N.U.
Network Evolution – Beyond Metro : How far Network Evolution – Beyond Metro : How far ??
You will need more photons forYou will need more photons forYour desktop PC / ProcessorsYour desktop PC / Processors
Electronics-photonics must converge !
Photonic Systems Lab School of EECS, S.N.U.
Two pillars of information revolution: Si IC & Two pillars of information revolution: Si IC & photonicsphotonics
WDM
vsvs
“A chip that can transfer data using laser light”, NYT, 20060918 By Intel and UC-Santa Barbara
“$6 million project to develop silicon-based laser”, 20060804 By MIT, the Microphotonics Center from US DoD Using nanocrystalline silicon as an sensitizer for Er
“Electronics-photonics must converge”, MIT, 20050520 By MIT from 3-year study
Photonic Systems Lab School of EECS, S.N.U.
Status of Photonics – Compared to ElectronicsStatus of Photonics – Compared to Electronics
Electronics : Vacuum tube Transistor IC VLSI Common User
$’s per 0.1M 100’s M Gb Memory
TO OPEN THE PHOTONIC AGE, compatible to that of semiconductor industry,
Need Cost reduction
Need Smaller Footprint
Need Integrated functionality
Need optical power lines (amplification function)
25% of the material cost is in the package
Another 25% is in the assembly
Beyond automation and off-shore assembly
Packaging really hasn’t advanced much until recently Costly 70’s-era technology Poor signal integrity Poor Thermal properties
Need : New materials, Athermal designs, and Packaging standards
OpticalSub-Assembly
Electronics Sub-Assembly
Zolo Technologies
Photonic Systems Lab School of EECS, S.N.U.
Challenges and PromisesChallenges and Promises
Challenges in achieving Photonic Age -- if it comes ^^; Cost 10’s of $ Footprint Size of PCMCIA Functionality More than Serial integration
Promises made to meet above challenges, with some technologies OEIC mostly for active devices Compound semiconductor PLC mostly for passive devices Silica, Polymer MEMS mostly for switching devices Silicon, Glass, etc.. EDWA mostly for amplification devices Silica Hybrids Si-Photonics Plasmonics Ph-Xtals ….. ….
How far do we need to go ?
Is it really possible to meet these Promises ?
Let’s sit back and look at the status of Silica based technologies (EDWA / PLC )
Photonic Systems Lab School of EECS, S.N.U.
Si Photonics – Optical Communication in the Si Photonics – Optical Communication in the ChipChipLeveraging the astronomical Si processing technology for photonicsPhotonics based on Si-based materials and Si-compatible processesPassives, Modulators, Detectors but still missing Photon Generators
0.5 m bend
0.5 m splitter
0.5 m bend0.5 m bend
0.5 m splitter0.5 m splitter
Photonic Systems Lab School of EECS, S.N.U.
Discrete
Gain
PLC
Loss
Discrete components
??????
Integration
EDFA
EDWA
What are we missing ? - Functionality / SizeWhat are we missing ? - Functionality / Size
For Photonics, there is lack of optical power lines which is compatible to that of electrical PCB
For Increased data rates, we need more photon (per bit) : Photon generator (amplifier, laser)
For SOA, with its strong electron - electron interaction and high noise figure
For EDWA, true integration is impossible after certain level (e.g. Splitting OA) : Only serial
??????
Integration /Functionality
Cost
PLC
EDA
PLC + EDA
High Power DFB
Not allowed by physics
Photonic Systems Lab School of EECS, S.N.U.
Challenges in Amplifier TechnologyChallenges in Amplifier Technology
Gbps/user Gbps/user need more photons/bit, but not with $1K/unit nor at current size !! need more photons/bit, but not with $1K/unit nor at current size !!
OITDA2000
Photonic Systems Lab School of EECS, S.N.U.
1962Proposal for optical amplifier first published J.E. Geusic and H.E.D. Scovil at ATT
Stimulated Raman scattering first observed E. Woodbury and Won Ng
1964 optical fiber amplifier demonstrated E. Snitzer using Nd doping for 1060-nm signals
1966 Proposal for glass light waveguides By K.C. koa and G. A. Hockman
1970
First continuous operation of diode laser at room temperature simultaneously demonstrated
Hayashi and M. panish at ATT.
and Z.I. Alferov at loffe institute(USSR)
Mass production of quality optical fiber Corning
1976 First major trial of commercial lightwave system Atlanta, Georgia(USA), without optical amplifiers
1983 First demonstration of doped single-mode fiber By ATT
1984First demonstration of 1550-nm operation Without optical amplifiers
5 wavelength CWDM in 1310-nm range By Toshiba, using 5-nm spacing
1987First EDFAs simultaneously developed R.J. mears, D. Payne. et al at university of Southa
mpton, and E. Desurvire, et al, at ATT
1989
Diode-pumped EDFA demonstrated By m. Nakazawa
First commercial EDFA introduced By Oki Electric
First commercial SOA introduced By BT&D Technologies (now Agilent)
1993 First major installation of optical amplifiers By MCI
1996 First installation of EDFAs into undersea links TPC-5 and TAT-12,13
1999 First EDWAs introduced MOEC and Teem Photonics
Amplifier evolution before millenniumAmplifier evolution before millennium
Photonic Systems Lab School of EECS, S.N.U.
20 30 40 50 60 70 80 90 100 110 1200 100
1.0
3.0
4.0
2.0
Rel
ativ
e C
ost
(A
.U.)
Bandwidth (nm)
Nortel Networks,1999
Amplifier – Bandwidth and CostAmplifier – Bandwidth and Cost
Gain media (whatever)Pump laser diode
PumpMUX
Tap Tap
Photodiode
Photodiode
IsolatorIsolator
DGFF
Photonic Systems Lab School of EECS, S.N.U.
Amplifiers – Any challenges left ?Amplifiers – Any challenges left ?
Optical Amplifier now 40 + year old, mature technology
Researchers have touched most issues on amplifiers Gain flattening Transient Temperature Power Conversion efficiency Noise, Scattering, Fiber structure, Host materials, Co-Dopants
Various types of OAs have been commercialized, by numerous vendors EDFA TDFA Raman Hybrid EDWA SOA (bulk, QW, QD)
Not much issues left for OAs, especially for LH, trunk line applications (personal opinion)
Let’s sit back and look at the Technology / Bottlenecks of OA for Metro and beyond
Photonic Systems Lab School of EECS, S.N.U.
Photonics : Different material / structure for each function, with high losses
1st Generation of Integration : Parallel (Laser, Detector, VOA arrays)
2nd Generation of Integration : Serial (ILM, Router, Receiver..)
Amplifier : 10-20 components with intensive package SERVING JUST ONE FUNCTION
NOT have been integrated with any other functional devices
Size reduction achieved to reasonable level to Metro, but not yet enough
Cost reduction achieved to reasonable level to Metro, but not yet enough
Is it possible to achieve above requirements with EDWA ?
Status of Amplifier – for Metro and beyond, to FTTHStatus of Amplifier – for Metro and beyond, to FTTH
x N
Pump LDIsolators
PD
Er-doped Waveguide Gain Block Array
Hybrid integrated activesPhotodiode Pump laser die
Yields ? Delivery ?
For N=8 : 80 1 part
Photonic Systems Lab School of EECS, S.N.U.
The current status of EDWAThe current status of EDWA
Exactly the same schematic as that of an EDFA
Efforts on the amplifying section only : > 10 M$ to make the cheapest part cheaper
Larger than the smallest available conventional EDFA
Need every component in one plane : severely restricts further reduction in size
Integration no more than an addition : Amplifying splitter = AMP + splitter
Photonic Systems Lab School of EECS, S.N.U.
Story behind the Limitation - CostStory behind the Limitation - Cost
For EDFA & EDWA, optical excitation occurs through direct photon absorption Very small absorption cross section (210-21 cm2)
Requires a long interaction length btw pump and signal Efficiency, Size Narrow absorption band – requires finely tuned lasers
Requires an expensive pump LD with wavelength (temperature) control Cost
Cost-centered view of an EDA
Pump laser diodePump laser diode
$1.53m0.98m0.80m0.66m
4F9/2
4I9/2
4I13/2
4I11/2
4I15/2
Er Er energy level diagramenergy level diagram
Energy level determined by QM
Photonic Systems Lab School of EECS, S.N.U.
Splitting Section
Amplifying Section
Reflecting mirror
Half MUX/ DMUX
Story behind the Limitation - StructureStory behind the Limitation - Structure
PLC and EDWA shares the same platform but the real integration is Difficult
Limited to serial integration Marginal reduction in the footprint with lower chip yield
Point amplification impossible Series of resistors and filters adds in system noise
Photonic Lightwave circuit without optical power line, EDWA as a mimic of EDFA
Serial Integration : Lower Yield 2-D Structure : Point Access Impossible
Photonic Systems Lab School of EECS, S.N.U.
Story behind the Limitation - MaterialStory behind the Limitation - Material
PLC is a stabilized, patterned fiber arrays using the same material
Mode size limitation dictates the minimum device size (much bigger than memory chip)
Wafer uniformity affects the yield of the chip higher index for smaller device size
To keep the Er numbers same within smaller volume, concentration have to be much higher
Increased Er concentration much lower ( ~ x 2 ) PCE from the quenching process
Photonic Systems Lab School of EECS, S.N.U.
Faults of Integrated Amplifiers proposed so far Faults of Integrated Amplifiers proposed so far
EDFA on a substrate Similar properties under similar conditions
competes against established products with only an incremental advantage Can never be integrated with anything else
can never truly “siliconize” photonics
Still requires an expensive pump LD Transfers the control over the final price of the device to LD suppliers The better you are, the worse this problem gets!
The smaller you get, you lose more pump power from Er quenching Dictates the smallest possible size of EDWA Not different at all when compared to EDFA again
Current OA technology not enough to support for metro – access network Cost Too high Photon Price, dictated by Electrical – Optical – Optical pumping Footprint Limited by Erbium on Silica wafer Functionality Limited by 2-D structure
Any solutions… ?Any solutions… ?
Photonic Systems Lab School of EECS, S.N.U.
Compound Semiconductor Bandgap - electrical : fast, strong interaction modulation, switching Strong interaction Smaller device size Energy source (electrical pump) independent from signal plane Feedback structure : LED FP, DFB but at much increased cost Bandgap engineering Wider, adjustable bandgap Difficulties in pigtailing Cost Differences in refractive index with fiber AR coating for SOA
Silica base Rare Earth Atomic level - optical : slow, weak interaction amplification without crosstalk Weak interaction Larger device size, Low efficiency Energy source (optical pump) requires waveguide Feedback structure : Fiber laser but no modulation capability Bandgap engineering None Compatibility in Pigtailing
Next generation Optical Amplifier – photon wavelength converter Eliminate an expensive LD source : just need to provide inversion COST Require dimensional separation of Pump and Signal plane FUNCTIONALITY Need stronger interaction mechanism for the excitation FOOTPRINTS
Contemplations on Photon GeneratorsContemplations on Photon Generators
Photonic Systems Lab School of EECS, S.N.U.
Si-Photonic Optical Amplifier ?Si-Photonic Optical Amplifier ?
Photonic Systems Lab School of EECS, S.N.U.
Pump photonsInteracting medium
Conversion mechanism
Signal photons
Signal photons
SiO 2
(host matrix)
Si nanoclustersEr ions
20 nm
Nanocrystal-Si sensitized EDWANanocrystal-Si sensitized EDWA
Amplifier is Wavelength Converter in its nature
Why do we use expensive coherent photons ?
Photonic Systems Lab School of EECS, S.N.U.
Material propertiesMaterial properties
1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65102
103
104
105
0 10 20 30 4010-2
10-1
100
Inte
nsit
y (a
.u.)
Wavelength (m)
with 477 nm pump with 980 nm pump
Time (msec)
PL
Int
ensi
ty (
a.u.
)
Continuous excitation spectra from IR to UV: anything bluer than green works!
No need of Frequency control (or cooling)
>100 times Er3+ luminescence intensity even with half the photon flux
nc-Si completely dominates excitation (100 x larger with 477nm than 980nm)
Photonic Systems Lab School of EECS, S.N.U.
SRSO / Er layer depositionSRSO / Er layer deposition
Deposition process ECR – PECVD (electron cyclotron resonant plasma enhanced chemical deposition) Silicon rich silicon oxide to construct silicon nanocluster Silicon contents control : Ar , SiH4, O2 (automated MFC) Evaporation / sputtering Er
Microwave
Sampleholder
SiH4, O2 gas(99.999%)
Ar gas(99.9999%)
Arplasma
Er Target(with negative bias)
Load lockChamber
TMP
Sampleholder
Photonic Systems Lab School of EECS, S.N.U.
Silicon nanocrystal controlSilicon nanocrystal control
Silicon nanocrystal Controlled by RTA annealing condition / silicon contents
Best energy coupling condition to Er ions
Size control : Quantum energy state of nanocrystal
State control : Crystal or amorphous
Photonic Systems Lab School of EECS, S.N.U.
Bulk performance measurementBulk performance measurement
PL measurement PL intensity and lifetime for various pump wavelength (980nm for Er, 477nm for NC-Er)
Activity of silicon nanocluster and Er, coupling efficiency
RBS measurement Atomic composition estimation for layer depth
Photonic Systems Lab School of EECS, S.N.U.
Waveguide characterization (amplification)Waveguide characterization (amplification)
Butt-coupled tapered fibers for signal input and output
15mm linear array of commercial, 470 nm LEDs
Need to clear the fibers and cover glass: 2mm separation between LED and waveguide, pump only center 5mm portion of the waveguide
Ridge WaveguideW 8 m x L 11 mm
LED arrayW 1,000 m x L 5 mm
H 2 mm
Photonic Systems Lab School of EECS, S.N.U.
Wavelength-dependence of signal changeWavelength-dependence of signal change
1515 1520 1525 1530 1535 1540 1545
-3
-2
-1
0
1
2
3
Sig
nal C
hange (
dB
/cm
)
Wavelength (nm)
Laser on (24W/cm2)
Laser on (16W/cm2) LED on Pump off
Signal change: Itrans(P)/Itrans(0): typical inversion curves for Er3+
With LED pump: low pump density due to unoptimized alignment
lower inversion, optical gain at 1545 nm
Simulation of high LED pump power with 477 nm laser:
full inversion with 3 dB/cm optical gain at 1533 nm
1532 1533
1292 1294
Sig
nal
Inte
nsit
y (a
.u.)
Wavelength (nm)
LED On LED Offa)
Wavelength (nm)
Sig
nal
Inte
nsit
y
Photonic Systems Lab School of EECS, S.N.U.
Numerical Assessment / DesignNumerical Assessment / Design
Parameters from experimental results Much larger effective excitation cross-section and signal absorption cross-section Emission cross-section from PL measurement Absorption cross-section from McCumber relation
Simulation scheme (top pumped NC-Si EDWA) 2-D propagation equations (with 10x10x400 segments) 1500 ~ 1610 nm with 1nm resolution
Photonic Systems Lab School of EECS, S.N.U.
Population inversion characteristics of NC-Si ErPopulation inversion characteristics of NC-Si Er
Much larger pump absorption cross-section than signal emission cross-section Over 50% inversion with small # of pump photons (Left-shift of red region in below figures) Top pumping scheme Large doping area than conventional EDF
Doping area confined to the center of the fiber core for high inversion (conventional EDF) Large doping area Enhancement of overlap factor with signal high gain per length
Pump intensity (dBm/cm2)
Sig
nal
inte
nsi
ty (
dB
m/c
m2 )
Inversion of conventional EDFA Inversion of NC-Si EDWA
Pump intensity (dBm/cm2)
Sig
nal
inte
nsi
ty (
dB
m/c
m2 )
Populationinversion
Photonic Systems Lab School of EECS, S.N.U.
Device Structure & FeasibilityDevice Structure & Feasibility
Performance comparison 4 cm EDWA without coupling loss NC-Si EDWA with type A core (7x7 μm2) Type A core EDWA with bottom mirror (100% reflection)
Large gain by reusing of wasted pump power
Adiabatic designed large core (type B, 100x7 μm2) Saturation gain enhancement by increasing pump collection area Small signal gain enhancement by overlap factor enhancement
Type A w/ mirror
Photonic Systems Lab School of EECS, S.N.U.
High intensity visible (blue) pump LED
Chip LED for illumination application (Cree)
Max 25W/cm2 (hard contact)
Easy to align (waveguide width 50um < LED 250um)
LED Die-Bonding pattern Emission of LED Array(0.3x3 cm)
7mW(at 20mA) x 64 Chip size : 300um x 300 um Array size : 0.03(cm) x 3(cm) Total Power : 5W/cm2
Optimization : Pump LEDs Optimization : Pump LEDs
Photonic Systems Lab School of EECS, S.N.U.
Gain: 2.4dB/cmPL : 93000LT : 6.3 ms
Optimization : Material Composition Optimization : Material Composition
x 17
x 12
Estimated result
Gain: 0.2dB/cmPL : 8000
LT : 9.3 ms
Experimental result
Evaporation Sputtering
Photonic Systems Lab School of EECS, S.N.U.
Schematic of a SRSO based VCPAC (pump WDM removed)
Pump light
SRSO wafer
LED Pump array
VCPAC Splitter (Splitting section = Amplifying section)
Amplifying Splitter
Examples & Implications in the applicationsExamples & Implications in the applications
Splitting SectionPump WDMs
Pump & Signal
Amplifying Section
Amplifying Section
Ultra-compact, low-costUltra-compact, low-cost True integration for Active PLCTrue integration for Active PLC
Totally NEW concept, Reduced Complexity & Higher Chip Yield !Totally NEW concept, Reduced Complexity & Higher Chip Yield !
Photonic Systems Lab School of EECS, S.N.U.
Much things you can do with NANO Si !!That’s a good news for Photonics Engineers
Summary Summary
# of Am
plifier W
orldw
ide
# of nan
o-particle W
orldw
ide
# of Am
plifier E
ngin
eers
Photonic Systems Lab School of EECS, S.N.U.