gtti08 fotonica avanex.ppt [modalità compatibilità] drivers, is reduced by decreasing the...

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Evergreen Lithium Niobatefor optical components

The Italian Challenge

©2007 Avanex, Inc. All rights reserved. CONFIDENTIALITY NOTICE: The information contained in this presentation is Avanex confidential information. Any dissemination, distribution or copying of this presentation or disclosure of the information contained within by any unauthorized person is strictly prohibited.

Michele Belmonte

Avanex

Bangkok, ThailandSan Donato, ItalyHorseheads, NY

Regeneration R&D

Manufacturing Exit Complete Modulation R&D Centralized Operations Center

Transmission R&D

Nozay, France

Fremont, CA

LiNbO3 Fab Operations Logistics for CM Partners

Manufacturing Transition to CMs

Shanghai ChinaM lb FL


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Headquarters

MIM R&D

Shanghai, ChinaDevelopment Center

Melbourne, FLTransmission R&D

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Avanex S. Donato: Historical Background

1988 – First Niobate process

Optical Components

Submarine SystemsTerrestrial

Systems

10%90%


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Components

Components philosophy

Products must be ready before the market requires them

• It is difficult to get this target

Components availability allows development of systems

• No components no system• Development of Components together with Systems


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Cheaper but• Smaller• More functionalities integrated

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Who is LiNbO3?

Well known source for discrete components, especially “passives”• Modulators for different applications (analog and digital)Modulators for different applications (analog and digital)• Fast switches are another field where niobate is playing a role

providing that the number of ports are reasonable (2x2 or 4x4) • Other devices such as AO Filters and lasers (together with

modulators) were also demonstrated

• The next challenges for LiNbO3 modulators are:


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– Making them smaller and smaller (few millimeters?)– Lowering the driving voltages (1V or less)– Increase the speed (100G and beyond) and use doable drivers– Cost, cost, cost

3rd youth of niobate

1st Spring• Externally modulated lasers• IL

2nd Spring• Amplifiers long reach so IL no more a problem• Other cheaper technologies available: EML

3rd Spring• Tunable laser arrived: Niobate is transparent

M f ti liti b i t t d I P


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• More functionalities can be integrated on InP

4th Spring?• See last slides of the presentation

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LiNbO3 modulators evolution

Higher integration level• Smaller devices• I t ti f dditi l f ti• Integration of additional functions

Transmission capacity• Bit Rate increase

(40 Gb/s, 100 Gb/s)


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Cost reduction• (Component level)• System level

10 Gb/s : Reducing system cost

Networks deployment at 10 Gb/s in the last years mainly involved metro/regional links

• As network dimension increased, development of extended reach transmitters allows to avoid dispersion managementTransmission reach:

– Zero chirp NRZ modulation 1000 ÷ 1200 ps/nm (~ 70 km)– Chirped NRZ 1600 ÷ 2000 ps/nm (~ 100 ÷125 km)– Duobinary modulation > 3200 ps/nm (> 200 km)


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• Cost of electronics within network cards/transponders, and particularly of modulator drivers, is reduced by decreasing the modulator driving voltage

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Optically chirped modulators

Groundelectrode

Hotelectrode

Groundelectrode

LiNbOx

Groundelectrode

Hotelectrode

Groundelectrode

LiNbOx

Groundelectrode

Hotelectrode

Groundelectrode

LiNbOx

Groundelectrode

Hotelectrode

Groundelectrode

LiNbOz

Groundelectrode

Hotelectrode

Groundelectrode

LiNbO

Groundelectrode

Hotelectrode

Groundelectrode

LiNbOz

Groundelectrode

Hotelectrode

Groundelectrode

LiNbO LiNbO3

Waveguide Buffer layerz

LiNbO3


LiNbO3


X-cut zero chirp LiNbO3 modulator transverse geometry

Z-cut electrically chirped LiNbO3 modulator transverse geometry

X-cut optically chirped LiNbO3 modulator transverse geometry

30

60

90

120

150

Electrical chirp

0 1 0 1

LiNbO3

Waveguide Buffer layerx

LiNbO3

Waveguide Buffer layerLiNbO3

Waveguide Buffer layerx

LiNbO3

Waveguide Buffer layer


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Optically chirped modulators possess a finite extinction ratioThe dynamics of induced chirp is different

Optical chirpElectrical chirp Optical chirpElectrical chirp

210

240

270

300

330

180 0

Optical chirp

Optical vs. Electrical chirp

0.5

1

Electrical chirp Optical chirp Freq. variation

Output power0.5

1

Electrical chirp Optical chirp

0.5

1

Electrical chirp Optical chirp Freq. variation

Output power

Electrical chirp

-1

-0.5

0

-1

-0.5

0

-1

-0.5

0

Electrical chirp

Optical chirp

O ti l hiEl t i l hi

Time resolved chirp behavior Spectral enlargement measurement


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Optical chirp provides smoother frequency variation over the pulseAlso, with optical chirp, spectral enlargement is limited

Optical chirpElectrical chirp

P. Bravetti et al., Phot. Techn. Lett. Vol 17, no 3, pp 564 - 567

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Transmission performances

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185

.

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12

13

14

15

16

Req

uire

d O

SNR

@ B

ER=6

e-5

DuobinaryOptical chirpElectrical chirpZero chirp


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Required OSNR @ BER=6e-5 for different modulation formats

110 25 50 75 100 125 150 175 200 225

Propagation length [km]

Duobinary – implementation

Duobinary format introduces phase alternation betweenadjacent symbols, which allows for strong spectralfiltering while still minimizing the effect of ISI. Filtering enhances tolerance to chromatic dispersion

Data Encoder LPFDriverData Encoder LPFDriver

filter


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The filter has been integrated within the modulator packageLPF is directly connected to LiNbO3 chip to minimize RF transitionsSynthesis of both filter and modulator frequency response has been optimized for mutual match

electrical electrical after LPF optical

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Frequency response

Rippling frequency response (both amplitude and phase) is the main

Frequency response and group delay of different filters and corresponding eye diagrams


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source of eye diagram performances.Synthesis of optimal frequency response of the series filter + modulator is crucial for modulator performances

P. Bravetti et al., Phot. Techn. Lett. vol 16, no. 3, pp 2159 – 2161

Duobinary optimization

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

BER

Matched

Unmatched(commercial)


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Both-ways filter and modulator frequency reponse optimization allows for improved jitter and OSNR performances

1.00E-11

1.00E-10

10 12 14 16 18 20 22OSNR (dB)

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Low driving voltage modulator

Rationale: • a class of low cost drivers, originally developed for electro-absorption

modulators, with output voltage <3V are available.• By reducing the driving voltage to <3V, we make LiNbO3 modulators

compatible with these drivers, enabling cost saving at transponder level

Alternatively to prior structures, we proposed ferroelectric domain engineering in LiNbO3 to increase modulation efficiency:

“Classical” z-cut in single domain:Type Structure Vpi Chirp RF drive

#1 Standard CPW ≈12 V*cm ≠ 0 (-0.7) Single

#2 Dual drive CPW ≈8 V*cm 0 (in principle any Dual (opposite sign Voltages)


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#2 Dual drive CPW 8 V cm 0 (in principle any value)

Dual (opposite sign Voltages)

“Novel” z-cut with domain inversion:#3 CPW modulator with half

line reversedIdentical to #1 Variable,

also ≈0Single

#4 z-cut single drive (Avanex implementation)

Close to #2 0 Single

Domain engineered structure

Previous approach for single ended, zero chirp low driving voltage modulator

Our implementation

Domain inversion causes opposite signs of the electrooptic coefficients in each


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Domain inversion causes opposite signs of the electrooptic coefficients in each half of the transverse sectionBoth waveguides are placed under the same hot electrodePush-pull modulation is possible with single drive RF electrodeElectrooptic efficiency is strongly enhanced vs. conventional z-cut chirped modulatorSymmetry of electrodes reduces thermal drift considerably

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Results

Good electrooptical

SEM image after HF etching of domain engineered LiNbO3 structure

Frequency response (S21)


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Good electrooptical performances obtainedEye diagram performances with EAM drivers are comparable to std. modulators

Eye diagram with EAM driverF. Lucchi et al., Proc. OFC 2007, paper

Small form factor modulators

LiNbO3 Chip

3 “

48 mm

Small form factor modulator is

TransponderXS-10

Modulator


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suited to next generation transponders/transceiversDriving voltages are compatible with std drivers

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40 Gb/s overview

High-bandwidth, flexible and dynamicnetwork systems are driven byapplications such as

• IPTV networks• Cellular systems• New deployment in emerging markets

Video is the assumed to be the killer application for large bandwidth optical networks


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The industry is still not at the benchmark “2.5x of 10G” but costs are decreasing

• PMD and chromatic dispersion compensation need to be factored in for a true apples-to-apples comparison

40Gb/s modulation formats

The beauty of the 40Gb/s solutions being devised today is that they can operate successfully by plugging interfaces into existing 10Gb/s systemsCongestion on a fiber can be alleviated by implementing 40Gb/s line cardsVarious modulation formats are being implementedg p

40 Gb/s NRZ DB (CS(RZ))DPSK (RZ) DQPSKChannel Spacing 100 50 100 (NRZ: 50) 50 Complexity Tx low medium/low low highComplexity Rx low low medium highBitrate single channel 40 40 40 20RZ possible N/A possible possibleAdvantage Simple CD tolerance 3 dB sensitivity

improvementCD / PMD tolerance

Disadvantage Low CD/PMD tol. Poor OSNR perf. More complex Rx More complex TxMore complex Rx


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Uncompensated link length 2 km 20 km (1300 nm) 12 km 4 km 10 km

Max. transmission distance SR solution ~ 600 km NRZ: ~ 1500 km(RZ: 10.000 km) ~ 1000 km

Comment TRx Available Mature Solution LN Performance

Tx commercialRx Standard

CommercialField Trials

First commercialTRx

p

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40 Gb/s NRZ, DPSK, duobinary

NRZ, DPSK: conventional 40 Gb/s MZ modulator. Low driving voltage needed for 2Vπ modulationπ

Duobinary modulation:same approach as @ 10Gb/s

• Integrated filter


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• Filter + modulator series optimization

40 Gb/s (D)QPSK

Optical IN Optical OUT

RF1 RF2 Vb2 Vb1 Vphase

Integration of two parallel MZI on the same chip is the preferred approach


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Preliminary results

NRZ after Rx demodulator With pulse carver

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Next: 100 Gb/s?

Option 1• 100G could supplant 40G before 40G begins a serious volume ramp

Option 2• 100G is an evolution of 40G with room in the marketplace for both100G is an evolution of 40G with room in the marketplace for both

Option 3 • All the talk of 100G is just a ploy to get 40G vendors to drop their prices

Anyway, Dual-Polarization QPSK w/ coherent detection will be the standard approach towards 100 Gb/s

A


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BC

D

Next future components?

At transmitter side: more integration

O ti l OUTOptical IN

RF11 Vb22Vb21Vph2RF12 RF21 RF22 Vb12Vb11Vph1

Optical OUT


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At receiver side:• 90° hybrids• Integration of O/E converters

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Conclusions

After more than 3 decades Niobate is still the material of choice for optical componentsp pPromising for advanced modulation formats for high speed link More components integrated on single substrate/package will enable the development of new generation transmission systemsD l t d f b i ti f t t f th t d i


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Development and fabrication of state of the art devices is the mission of Avanex in Italy

gtti08 fotonica avanex.ppt [modalità compatibilità] drivers, is reduced by decreasing the...

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