High Performance, Low Cost PIN, APD Receivers in Fiber Optical - - PowerPoint PPT Presentation

WOCC-2005

High Performance, Low Cost PIN, APD Receivers in Fiber Optical Networks and FTTx Applications

Hui Nie 4/23/2005

WOCC-2005

Receiver Applications

Long-Haul Backbone Metropolitan Backbone Metropolitan Access Enterprise Access

Back Bone Core Nodes LR and VLR I nterface Cards Metro Transport Line Cards Metro Access Line

Cards ( ADM’s)

Transceivers Transponders OXCs

• FTTx Applications/Demands also heating up!

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Photodetectors and Optical Receivers

Introduction Photodetectors Technologies

Overviews PIN Photodiodes Avalanche Photodiodes (APDs) APD Design Trade-offs

Photoreceivers Technologies

Overviews High Performance MSA Compliant Receivers & ROSAs

PIN, APD ROSA in FTTx Applications

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Photodiodes Technologies

Overview PINs APDs

Etch-Regrowth Planar SACM APDs Buried-Mesa APDs w/ Regrowth Guard Ring Resonant-Cavity APD w/ Thin Multiplication Layer Wafer-Fused SHIP APD InGaAlAs/InAlAs Superlattice APD Waveguide APD Transit Time Bandwidth RC Time Bandwidth Surface-Illuminated PINs Waveguide PINs Traveling-Wave PINs

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Photoreceiver Sensitivities v.s. Bit-Rate

Bit Rate (Gbit/s)

0.1 1 2.5 10 20 40

Sensitivity @ BER=10-9 (dBm)

• 50
• 40
• 30
• 20
• 10

PIN OEIC PIN Hybrid EDFA Preamp APD Hybrid Quantum Limit

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• 50
• 40
• 30
• 20
• 10

20 40 60 80 100 120 140

Transmission Length (km) Received Power (dBm)

1.3µm 1.5µm

. 2 5 d B / k m 0.3 dB/km 0.4 dB/km 0.6 dB/km

EDFA+PIN APD+Amp. (+EDC)

PIN+Amp.

10 Gb/s Receivers Sys.

Dispersion limit

Receiver Systems & Applications (10Gb/s Systems)

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Industry Standard Top-illuminated Planar PIN

InP Substrate n++ InP Buffer layer n - InGaAs Absorption Cap Layer Zn Diffused p+ p+ Metal Contact Bonding pad SiNx AR coating Dielectric coating

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High-Speed Surface-illuminated Mesa PINs

Light Input SiNx Coating InP:Fe Substrate n InP p InP i InGaAs PMGI n-Metal Metal Reflector Alloyed p-Metal Air-Bridged Metal

• InGaAs/InP Graded Double

Heterostructure p-i-n

• Superlattice Interface Grading
• Small Mesa Size <10 µm2
• < 0.2 µm InGaAs Absorption Layer
• Undercut, Mushroom Mesa to

Minimize Parasitic Capacitance

• QE <25%@1.3 µm
• Hard to Manufacture
• Integrated Bias Circuit (Bias Tee

and Matched Resistor)

• Possible Wafer-Fusion DBRs to

Enhance QE

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Waveguide Photodetectors (WGPDs)

• Side-Illumination
• Optimize Bandwidth and

QE Independently

• Multimode Ridge

Waveguide

• Micro-Lenses Fiber

Coupling, Small Spot Size

• External QE>70%
• Bandwidth>100GH
• Can be integrated OEIC

Photoreceiver

p+ InP p+ InGaAsP i InGaAs -0.2 µm n+ InGaAsP n+ InP polyimide

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Traveling-Wave Photodetectors (TWPDs)

• Electrical Waveguide

Concomitant with Optical Waveguide

• Match Between Electrical

Wave and Optical Wave (50Ω)

• Eliminate RC Time Tradeoff
• Higher Saturation Power
• Bandwidth=172 GHz, QE~40%
• Small Geometry w=1 µm

1 µm

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Multiplication Process Enhance Performance

Multiplication region Distance Time

p+ n+ i + Injected electron Electric field Secondary hole Primary and Secondary electron x E(k) + +

Gain process will slow down transit-time! Figure of Merit: Gain-Bandwidth Product High Electrical Field near avalanche breakdown!

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APD Photocurrent & Gain vs. Temperature

1.E-07 1.E-06 1.E-05 1.E-04 10 20 30 40 50 60 70 Reverse Voltage, volt Current, A

1 2 3 4 5 6 7 8 9 10 11 12 13

Gain

n40C n20C 0C 25C 50C 85C M_40C M_20C M0C M25C M50C M85C

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Receiver Sensitivity vs. APD Gain, TIA noise

• 36
• 34
• 32
• 30
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• 24

1 5 9 13 17 21 25 29

APD Gain Receiver Sensitivty (dBm)

Sen(120nA) Sen(250nA) Sen(350nA) Optimum-M

Locus of Optimum APD gain APD Noise < TIA Noise APD Noise > TIA Noise

How does APD Enhance Rx Sensitivity?

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Planar Separate Absorption, Multiplication (SAM) APD Structure

n+ InP Buffer n- InGaAs abs. layer

n- InGaAsP layer

n+ InP Sub.

n+ InP Multi. n- InP cap layer

AR coating n-metal p-metal SiNx layer P+ Diffusion Guard Ring

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Planar SACM/SACGM APD

• InGaAs/InP Two-step

MOCVD

• Planar Structure
• Etch and Regrowth Charge

and Multiplication Region

• Diffusion controlled

Multiplication Layer (single Diffusion or Well Etching- Diffusion)

• Xd ~ 0.2-0.4 µm
• GB product = 122 GHz
• Noise Ratio k~0.45
• No Implant

n-Metal AR SiO2 p+ InP n- InP Multiplication n InP Charge

Grading Layer

n InGaAs

n- InGaAs Absorption n- InP Buffer n+ InP Substrate

Xd Xj tInGaAs

tmesa

tcharge

tBuffer

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Resonant-Cavity InGaAs/InAlAS SACM APD

• Resonant-Cavity Structure
• High QE ~ 75%
• Mesa Isolated
• SACM Configuration
• Thin InAlAs Multiplication

Region (200 nm)

• Lower Noise k ~ 0.18
• Bandwidth>20 GHz
• High Gain-Bandwidth

Product

Polyimide n+ InAlAs/InGaAs DBR

hυ

Probe Metal

n+ InP Buffer Layer

Semi-Insulating InP Substrate

Metal Ring Contact

Dielectric DBR

InGaAs Cap Ring Contact APD Active Region

n+ InAlAs

200 nm InAlAs Multiplication 60 nm InGaAs Abs. Layer

p+ InAlAs

150 nm p-InAlAs Charge 50 nm InAlAs Spacer 50 nm InAlAs Spacer

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Wafer-Fused SHIP APD

• Silicon Heterointerface

Photodetector (SHIP)

• Wafer-Fused Si

Multiplication Region

• Mesa Isolated (20-30 µm)
• Backside Illumination
• Bandwidth= 13 GHz
• GainxBandwidth= 315

GHz

• Reliability Issue

Au/Zn Contact PMGI p+ InGaAs n- InGaAs p-type Implant Bonding Interface

n-type Si Substrate

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Buried Mesa APD with Regrown Guard-Ring

• Mesa Etch and Regrowth

Isolation Layer (Patented)

• No Diffused Junctions and

Multiple Implanted GRs

• Regrowth p-InP Guard Ring

+ Implanted Guard Ring

• Bandwidth< 4GHz for OC-48

Applications (2.5 GHz)

• GB Product=37 GHz
• Sensitivity= -33 dBm
• Excess Noise Factor=0.4

P+-InP n-InP Mulutplication InGaAsP i-InGaAs n-InP Regrown p-InP Proton Implant Isolation

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Planar InGaAlAs/InAlAs MQW APD

Ti Implanted Guard-Ring AR Coating p-contact Sn Bump n+ InAlAs Cap InGaAlAs/ InAlAs Superlattice p+ InP Field Buffer P- InGaAs p+ InP SI-InP Substrate Zn Diffused Region

• SI InP Substrate
• Inverted Mesa Junction
• Ti Implanted Guard-Ring to

Decrease p-concentration of Field-Buffer Layer

• Dark Current Increase Due to

Implantation

• SiNX Passivation
• p+ Zn Diffusion Isolation
• Contact Metal Deposition
• Flip-Chip Bonding
• Cd=0.15pF, Cp=0.06pF
• RL=25 Ω to achieve

Bandwidth=15.2GHz

• Id=0.36µA@ M=10
• GB Product = 120GHz

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Waveguide APD

• Multimode Waveguide Structure
• Mesa Etch and SiNx Passivation
• InAlAs/InAlGaAs MWQ

Multiplication Layer ~0.25 µm

• InGaAs Abs. Layer ~ 0.3 µm
• Top and Bottom InAlGaAs

Cladding Layer ~ 0.8 µm

• Bandwidth= 20 GHz
• GB Product= 160 GHz
• Large Dark Current
• 1 µA @ 90% VB
• Edge Coupled w/ Lensed Fiber (3

µm Spot Size)

20 µm p+ InAlGaAs n-Metal InAlGaAs InAlAs/InAlGaAs MQW

n+ InAlGaAs InP Substrate SiNx

6 µm p-Metal

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Real-World APD Device Specifications

Quantum Efficiency, Responsivity Gain characteristics Bandwidth @ M=10,12 when PIN is low (Sensitivity) Bandwidth @ M< 4 when PIN is high (Overload) Primary Dark Current Excess Noise Factor Capacitance Breakdown Voltage

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Performance of APD comes with price!

• Trade-off 1: Bandwidth~ Responsivity
• InGaAs Absorption Layer Thickness
• Trade-off 2: RC Bandwidth ~ Transit Time Bandwidth
• InGaAs, InP layer thickness
• Device geometry
• Trade-off 3: BW@ M~10 ~ BW@ M~3
• Multiplication layer doping
• Diffusion junction depth control (Ehet control)
• Trade-off 4: Breakdown Voltage ~ Thickness, Doping
• InGaAs, InP layer thickness
• Multiplication layer doping

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APD Design- Balance between Trade-offs

APD Bandwidth vs. Gain

1 10 1 10 100

Gain 3 dB Bandwidth (GHz)

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TriQuint APD Chips

• Over than 15 years of design and volume manufacturing APDs used

in commercial communication systems (AT&T Bell Labs -> Lucent -> Agere -> TriQuint -> CyOptics?)

• High quality, high yield and low cost MOCVD epi
• Reliability proven with > 5000 hrs aging and >15 years of field use
• High-speed automated wafer level electrical and optical probing

systems

• Receiver performance demonstrated with high performance APD

chips

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Failure Rates vs. Activation Energy

Failure Rate vs. Ea

0.1 1 10 100 1000 0.4 0.5 0.6 0.7 0.8 0.9 1

Activation Energy, eV P rojected Failure R ate, FIT

MOCVD APD

With the estimated Ea of 0.96 eV, these devices have very small FIT (< 1 FIT). With >5000 hrs accelerated aging test, activation energy is extracted.

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TriQuint Receiver Product Family

Traditional butterfly package

receiver

MSA small-form-factor

surface-mounted Receiver

Ceramic packaged ROSA TO-can based ROSA

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APD & PIN MSA Receivers

Key Advantages

• MSA Small Form Factor
• Surface Mount
• High Sensitivity & Overload

R195A typical –26 dBm, -3dBm R195P typical –19 dBm, +1 dBm

• Small Group Delay Variations
• Good Linearity

700mV Output Voltage Swing

• Excellent OSNR Performance

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MSA APD Receivers

• 26 dBm, M=10 9.953 Gb/s, 1550 nm, 2E31 – 1 PRBS

Eye

• 3 dBm, M=3

BER

TriQuint R195A BER vs. Temperature @ 9.95Gb/s

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• 30
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• 24
• 22
• 20

Power (dBm) BER

T= 0 C T= 25 C T= 50 C T= 70 C

10

• 12

10

• 4

10

• 8

10

• 6

10

• 10

< 1.0 dB Penalty from 25C to 70C

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10G APD Receiver OSNR Performance

Tx

9.95328 Gb/s

M

Attn.

EDFA

Attn.

M

R195A Rx BERT OSA

BPF

LM (Vth Adjust)

R195A BER at 18dBm OSNR (Vth optimized)

• 22
• 20
• 18
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• 14
• 12
• 10
• 8
• 6
• 4
• 2

Power (dBm) BER

unit 1, opt. -20dBm unit 2, opt. -20dBm unit 3, opt. -20dBm unit 4, opt. -20dBm unit 5, opt. -20dBm

10

• 12

10

• 4

10

• 8

10

• 6

10

• 10

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BER vs. Vpd over Temperature

* For each temperature the optical power was adjusted to obtain a BER in the range of 4e-11 to 9e-11.

TriQuint R195A BER vs. Vapd, 9.95Gb/s, T=0, 25, 50, 70 OC

20 21 22 23 24 25 26 27 28 29 30 31 32 Vapd (V) BER

T= 0 C T= 25 C T= 50 C T= 70 C

10

• 12

10

• 4

10

• 8

10

• 6

10

• 10

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Next Generation MSA Receiver & ROSA

• 28 dBm, M=9

9.953 Gb/s, 1550 nm, 2E31 – 1 PRBS

Eye

+1 dBm, M=3

BER

• 32
• 30
• 28
• 26
• 24
• 22
• 20

Power (dBm)

BER

10

• 12

10-4 10

• 8

10

• 6

10

• 10

7/4/2005 32

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Fiber Transmission Experiments

100 km

(a) (b)

0 km

Eye diagrams back-to-back, and after 100 km transmission. (a) Optical. (b) Electrical.

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Path Penalty after 100 km Fiber

Receiver Sensitivity vs. APD Vpd (B/B, 100Km)

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• 29.5
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• 28.5
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• 27.5
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• 26.5
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• 25.5
• 25
• 24.5
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24 24.5 25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30 30.5 31 31.5 32

APD Bias (Volt) Receiver Sensitivty (dBm)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4

Path Penalty 100km Fiber (dB) B2B 100Km

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PIN & APD ROSAs

Low cost, high performance XMD compatible 3.3V TIA Detector on carrier

TIA TIA APD flip-chip On carrier APD flip-chip On carrier

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100k 1M 10M 100M 1G

622M B- PON G/GE-PON π

ADSL

2000 2001 1998 Speed (bit/s)

final final IEEE802.3 FSAN FSAN,ITU-T

2003

155M B- PON ＰＯＮ系 ＰＯＮ系

100M-Ｅｔｈｅｒ MC GbE-MC 10M-Ｅｔｈｅｒ MC

ＬＡＮ（ ＬＡＮ（SS) SS) STM PON

Under development Commercial product

※G-PON：Gigabit-PON（FSAN） GE-PON:GigaEthernet-PON（IEEE802.3）

FSAN

Advancement in Access Advancement in Access

Under research

WDM-PON

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PON (Passive Optical Network)

A single, shared optical fiber serving 32 customers. “Passive” because no active electronics in access network, except for the end points.

Med-Small Office Residential Circuit/Packet Switch Optical Line Terminal (OLT) Ethernet N x POTS Optical Network Terminal (ONT) ONT ONT Central Office Splitter

FTTP Architecture

1550 nm broadcast 1490nm data 1310 nm data

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Market:

North America: 1-2M home for 2005 Verizon: About 150k Subscribers, 1M home passed. Plan to add 2M home by 2005 SBC: Field trial on 2004, and plan add 300K home on 2005 Japan: 2-3M homes for 2005 NTT: Plan spend $48B for 30M subscribers by 2010, add 1-2M subscribers on 2005 Yahoo BB: Strong competitor with 2M subscribers in 2005 plan Korea: Plan to add 10M subscribers by 2007, but no detail plan yet China: Still on earlier stage of deployment, a lot of trials Europe: About 400K Subscribers, not high level growth can see in the near future

Equipment:

• Optical Network Terminal (ONT):
• 1310 DFB or 1310nm FP for upstream
• 1490nm PD 1550nm analog detector for receiver
• Optical Line Terminal (OLT):
• 1490nm DFB for downstream data transmission
• APD for receiving
• Cost, cost and cost while not sacrificing performance!

FTTP Market

1310nm FP, DFB or 1490nm DFB 1.25G APD or PIN

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EPON & GPON Requirements

EPON & GPON Different Requirements

PIN mostly in ONT side APD mostly used in OLT side APD will be more common due to split ratio increases

1000BASE-PX10 1000BASE-PX20 G.984.2 Distance 10 Km 10 Km 20 Km Attn Range 5-20dB @ upstream 5-20dB @ upstream Class A: 5-20dB Class B: 10-25dB Class C: 15-30dB Output Power ONT: -1 ~ +4 dBm OLT: -3 ~ +2 dBm ONT: -1 ~ +4 dBm OLT: +2 ~ +7 dBm ONT: -2 ~ +3 dBm @ ClassB OLT: +1 ~ +6 dBm @ ClassB Receive Power ONT: -24 ~ -3 dBm OLT: -24 ~ +1 dBm ONT: -24 ~ -3 dBm OLT: -27 ~ -6 dBm ONT: -25 ~ -4 dBm @ ClassB OLT: -28 ~ -7 dBm @ ClassB EPON (IEEE 803.2ah) GPON (ITU-T)