weiner ofc 2008 pmd tutorial final

8/3/2019 Weiner OFC 2008 PMD Tutorial Final

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PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS LABORATORY

A.M. Weiner (OFC 2008)

Optical Spectral Processing /All-Order PMD Technology:

Compensation, Sensing, Emulation

A.M. Weiner

Purdue University

[email protected]

http://ece.www.ecn.purdue.edu/~amw

Funding:

PMD Compensation at Ultra-High Bit Ratesor





Outline

• Introduction to PMD (focus on all-order PMD)

• Optical spectral processing (pulse shaping etc.)

• Sub-ps pulse all-order PMD compensation experiments

• Extending to DWDM via hyperfine-resolution spectral dispersers

• Spectral polarization sensor (parallel sensing at under 1 ms)

• All-order PMD emulation (generation)





Polarization Mode Dispersion (PMD)

“Anatomy of a real fiber”

Poole and Nagel,

in Optical Fiber Telecommunications IIIA,

Academic Press (1997).

See also Kogelnik, Jopson, and Nelson,

in Optical Fiber Telecommunications IVB,

Academic Press (2002).

ΔτFor broadband inputs,random birefringences

lead to wavelength-

dependent polarization

scrambling and

wavelength- and

polarization-dependent

delays.





First Order PMD Narrowband inputs

• Fiber characterized by two principal states of polarization (PSPs), in general elliptical

• For input light launched along a PSP, output SOP is constant to first order in ω

• Two PSPs have a differential group delay (DGD) – Maxwellian distribution

• Valid only for small DGD (compared to pulse width)

2 2 2( ) ( ) / ( )PSP ω = Ω ω Ω ω

2 2

3 1

( ) ( ) DGDθ

ω = Ω ω ≈ω − ω

ˆˆout

out

ss

∂= Ω ×

∂ω

ŝ(ω1)ŝ(ω2)

ŝ(ω3)S3

S1

S2Ω(ω2)

θ

Poincaresphere

Poole and Giles, Opt. Lett. 13, 155 (1988)

Differential

group delay

(DGD)

1st Order PMD:

Small distortion –

Small bandwidth limit





M. Duelk and P. Winzer, IEEE 802. 3 High Speed Study Group, Nov. 2006





M. Duelk and P. Winzer, IEEE 802.3

High Speed Study Group, Nov. 2006

• Appropriate modulation format and FEC suggests impressive inroads against PMD

• For very speed systems or higher PMD fibers, PMD issues likely to remain important





Distorted

input

Polarization

splitter

Polarization

controller

Adjustable

delay

Polarization

combiner

Compensated

output

PMD Compensation

First-order optical compensator

• Applies only to small DGD

• less than a few tenths of pulse duration for RZ

• less than a few tenths of bit period for NRZ•Already challenging in view of:

• time-dependent, random PMD variations

• requirements for low outage probability (e.g., <10-5)

Split into PSPs, delay,

and recombine!

(or similar)

• Electrical compensation• Impairment resistant modulation format

• Optical compensation (bit-rate and format independent)





Limitations to First Order PMD Approximation

The autocorrelation bandwidth of the

PSP vectors is inversely proportional

to the mean differential group delay.

Foschini, Jopson, Nelson, and Kogelnik, Journal of Lightwave Technology 17, 1560 (1999)

Shtaif, Mecozzi, and Nagel, IEEE Phot. Tech. Lett. 12, 53 (2000).

0.64PMD B

DGD





All-Order PMD Effects

800 fs pulse distorted by PMD emulator with mean DGD ~ 5.5 ps

• Complicated frequency-dependent polarization scrambling

• Frequency- and polarization-dependent delays

• Will occur whenever the distortion approaches the pulse width or bit period

H. Miao, et, Opt. Lett. 32, 2360 (2007)





All-Order Optical PMD Compensation

TX Link RXCompensator

Controller Sensor

Complex

frequency-dependent

vector field

All-order PMD

(frequency-dependent

complex transfer matrix)

- Spectral polarimetry?

- Frequency-dependent

delay or phase?

-Complexity?

-Requirements on TX?

- Generate frequency-dependent

inverse matrix?

- Operate on frequency-dependent

vector field?

- Compensator synthesis in the time-domain (digital filter approach)

- Compensator synthesis in the optical frequency domain





Digital filter (time-domain) approach

All-Order Optical PMD Compensation

Cascaded all-pass filter elements – e.g., cascaded first-order compensator elements

C.K. Madsen, Opt. Lett. 25, 878 (2000)

Examples

- Cascaded polarization mode coupling in birefringent LiNbO3 – R. Noe, et al, Elec. Lett. 35, 652 (1999)

[Univ. Paderborn]

- Cascaded ring resonators in silica PLCs - C.K. Madsen, et al, JLT 22, 1041 (2004) [Lucent]

Challenges

- Large number of stages for all-order PMD

- Complexity of control problem grows with number of stages

- Compensation of various orders of PMD is coupled and must be considered simultaneously





-Pulse shaping-Dynamic spectral equalizers

-Dynamic wavelength processing

Parallel, Optical Spectral Processing

Spatial light modulator

Control of phase, intensity, polarization …

Frequency-by-frequency, independently, in parallel

Spectraldisperser

Spectral

combiner

Broadband input- Ultrashort pulse

- CW plus modulation

- Multiple wavelengths

Processed output





Femtosecond Pulse Shaping

• Diverse applications: fiber communications, coherent quantum control,

few femtosecond pulse compression, nonlinear optical microscopy, RF photonics ...

Examples:

Phase encoded

O-CDMA waveform;

square pulse

Fourier synthesis via parallel spatial/spectral modulation

A.M. Weiner, Rev. Sci. Instr. 71, 1929 (2000)

Weiner et al, Opt. Lett. 15, 326 (1990); IEEE JQE 28, 908 (1992)

Liquid crystal modulator (LCM) arrays:

•Originally phase-only, then independent

phase and intensity, now polarization•Down to ~msec response, hundreds of pixels

Basic 4-f optical system, plus spectral masking:

•Long pulses (Nd:YAG), fixed mask:

C. Froehly et al, Progress in Optics 20, 65 (1983)•100 fs pulses, fixed mask:

Weiner, Heritage, and Kirschner, JOSA B 5, 1563 (1988)





“Pulse Shaping” in WDM: Intensity Control

Manipulation on a wavelength-by-wavelength basisNo concern for phase or for coherence between channels

Ford et al, J. Lightwave Tech. 17, 904 (1999) [Lucent]

Ford et al, IEEE JSTQE 10, 579 (2004) [Lucent]

Wavelength selective add-drop multiplexer (and wavelength selective switches)

Spectral gain equalizer





Programmable Fiber Dispersion Compensation

Using a Pulse Shaper: Subpicosecond Pulses

• Coarse dispersion compensation using matched lengths of SMF and DCF

• Fine-tuning and higher-order dispersion compensation using a pulse shaper as a

programmable spectral phase equalizer

• Similar ideas apply to DWDM tunable dispersion compensation andfew femtosecond pulse compression.

Spectral phase equalizer

( )( )−∂ψ ω

τ ω =∂ω

A.M. Weiner, U.S. patent 6,879,426





Higher-Order Phase Equalization Using LCM

Input and output pulses from 3-km SMF-DCF-DSF link

Chang, Sardesai, and Weiner,Opt. Lett. 23, 283 (1998)

Input pulse

Output pulse

(with quadratic &

cubic correction)

Output pulse

(without phase

correction)

already compressed

several hundred times

Applied phase

• No remaining distortion!





460 fs transmission over 50 km SMF

-10 -5 0 5 10 15 20Time (ps)

I n t e n s i t y c r o s s - c o r r e l

a t i o n ( a . u . )

both second- and third-order DC by pulse shaper

without DCby pulse shaper

second-order DC

by pulse shaper

P h a s e (

r a d )

0

20

40

60

80

100

0 32 64 96 128

Pixel #

2π

π

(A)

(B)

Commercial DCF module (as is) with spectral phase equalizer

• ~ 5 ns after SMF

• 13.9 ps after DCF

• 470 fs after quadratic/cubic phase equalization

Z. Jiang, Leaird, and Weiner, Opt. Lett. 30, 1449 (2005)

Essentially

distortion-free!





“Pulse Shaping” in WDM: Dispersion Compensation Research

AWG pulse shaper and phase mask

Takenouchi, Goh and Ishii, OFC 2001 (NTT)

VIPA pulse shaper and curved mirror

Shirasaki and Cao, OFC 2001 (Fujitsu/Avanex)

Sano et al, OFC 2003 (Sumitomo)

• Either colorless dispersion compensation or independent fine-tuning of different channels

AWG pulse shaper and deformable mirror

Neilson et al, JLT 22, 101 (2004) [Lucent]

Grating pulse shaper and

MEMS deformable mirror array

( )( )−∂ψ ω

τ ω =∂ω





Frequency-Domain All-Order PMD Compensation

(Principles and sub-ps pulse experiments)

A.M. Weiner, U.S. Patent application 20020060760 (May 23, 2002)





An All-Order Compensation Scheme

(1) Distorted pulse:

(2) Sense and correct full spectrally dependent state of polarization

(3) Sense and compensate full spectral phase (generalized chromatic dispersion)

ˆ( ) ( ) ( ) ˆ ( )PMD in E a bω ω ω ω = +E α β

( ) ( )exp ( ) ˆin E j yω ω ω = ΨE

( ) ( ) ˆin E yω ω =E

(1) (2) (3)

Distorted input(vector field)

Equalize

spectral

phase

Alignoutput

SOPs

State-of-polarizationshaper

Phase shaper

RestoredpulseScalar field





All-Order PMD-Compensator Implementation

• Concatenated polarization and phase pulse shapers

• Wavelength-parallel polarimeter for control of polarization pulse shaper

• Ultrashort pulse measurement approach for control of phase shaper

(1542-1556nm)

(~576 fs pulse width)

(16-piece PM fiber)

(7.6 dB insertion loss) (4.5 dB insertion loss)

(Cross correlation with 72 fs

reference pulse; or FROG)

New LCMconfiguration

New

sensor

M. Akbulut, et al, Opt. Lett. 29, 1129 (2004); Opt. Lett. 30, 2691 (2005); OFC 2005 (post-deadline); JLT 24, 251 (2006)





State-of-polarization (SOP) Control

• Rotate

ARBITRARYPOLARIZATION STATE

into a

FIXED LINEAR STATE

• In an array in a pulse shaper configuration,many frequency components

can be SOP-rotatedindependently and in parallel

Birefringence axis

of LCM First Layer Birefringence axis

of LCM Second Layer

LCM Second

Layer

Operation

LCM First

Layer

Operation

SOP for a single wavelength

(OR a single LCM pixel)

RHCP

M. Akbulut, et al, Opt. Lett. 29, 1129 (2004)

Two liquid crystal layers, aligned at 90°/45°





Phase and Partial Polarization Control

• Two LC layers successively rotate

SOP about 45o point

• Polarization rotation depends on arc

length (retardance) difference

• together with a polarizer, this givesamplitude control (as in a spectral gain

equalizer)

• Phase modulation depends on total

arc length (total retardance)

Poincare sphere

Two liquid crystal layers, aligned at ±45°





Pure Phase Control

Liquid crystal layers at 45±

Poincare sphere

• With equal retardances, rotations

by two LC layers are equal and

opposite

• Output SOP = input SOP:

no polarization rotation

(independent of input SOP)

• Phase modulation depends on total

arc length (independent of input

SOP)





• Various ultrafast measurement techniques available

• Here we use the Gerchberg-Saxton algorithm

• Uses I (t ), measured via cross-correlation, and power spectrum

Spectral Phase Retrieval: 1st method

( )( ) j I e

β ω ω

( )( ) j t I t e

α

( )( ) j t E t e

α

( )( ) j E e

β ω ω

Use initial guessto start algorithm

FFT -1

FFT

Apply

intensity data

Apply power spectrum Typically 70-250 iterations

Apply phase

to shaper Measure new

intensity profile

Improved pulse

(Iterated G-S algorithm)





600 fs input pulse

through PMD emulator

(16 section PM fiber,

mean DGD ~1.3 ps)

PMD Distorted SOP Spectrum Corrected SOP Spectrum

-8 -4 0 4 8Time (ps)

-8 -4 0 4 8Time (ps)

-8 -4 0 4 8Time (ps)

-8 -4 0 4 8Time (ps)

Input Pulse (575.7 fs)PMD Distorted Pulse After SOP correction Recovered Pulse (630.8 fs)

All-Order Compensation Experiment (1)

M. Akbulut, et al, Opt. Lett. 30, 2691 (2005); OFC 2005 (post-deadline); JLT 24, 251 ( 2006)

Frequency-dependent polarization correction adds frequency-dependent phase





800 fs input pulse

through PMD emulator

(16 section PM fiber,

mean DGD ~1.3 ps)

PMD Distorted SOP Spectrum Corrected SOP Spectrum

-8 -4 0 4 8

Time (ps)

-8 -4 0 4 8

Time (ps)

-8 -4 0 4 8

Time (ps)

-8 -4 0 4 8

Time (ps)

Input Pulse (791.8 fs) PMD Distorted Pulse After SOP correction Recovered Pulse (696.3 fs)

All-Order Compensation Experiment (2)

M. Akbulut, et al, Opt. Lett. 30, 2691 (2005); OFC 2005 (post-deadline); JLT 24, 251 ( 2006)

Frequency-dependent polarization correction adds frequency-dependent phase





• Second-Harmonic Generation (SHG) Frequency-Resolved Optical Gating (FROG)

• Two-dimensional data set

• Iterative retrieval (much more robust than G-S)

• Innovations: extremely high sensitivity using A-PPLN waveguides; polarization

insensitive measurement operation

R. Trebino, “Frequency resolved optical gating”, KAP, 2000

2-D Spectrogram

with respect tofrequency and

delay

Spectral Phase Retrieval: 2nd method

H. Miao, et al, OFC 2007; Opt. Lett. 32, 424 ( 2007); Opt. Lett. 32, 874 ( 2007)





22 nW coupledfundamental power,

FROG error=0.007

600 fs pulse through PMD emulator with mean DGD ~1.4 ps)

Measured pulse

after SOP correction,

but before phase

correction.

Phase Sensing via FROGPulses measured after SOP correction, before phase correction

H. Miao, et al, OFC 2007





22 nW coupled

fundamental power,

FROG error=0.003

Measured pulse

after SOP and phase

correction

642 fs

600 fs pulse through PMD emulator with mean DGD ~1.4 ps)

Phase Sensing via FROGPulses measured after both SOP and phase correction

H. Miao, et al, OFC 2007

Robust: comparable results in several different experiments





All-Frequency PMD Compensator in Feedforward Scheme

P. B. Phua, Hermann A. Haus, and E. P. Ippen

Phua, Haus, and Ippen, JLT 22, 1280 (2004)

Frequency-dependent

PSP vector

via Poincare arc

method with

polarization

switching

Isotropicdispersion

compensation

Rotate PSP vector to common direction Frequency-dependentDGD compensation

Depiction of

PSP vectors

• Proposal and analysis, with some suggestions for implementation

• Sensing via launch polarization switching; differentiation of spectral polarimetry data





Wavelength-Parallel Jones Matrix Correction

( ) je

ψ ω

Chromatic

dispersion ( ) ( )

( ) ( )* * f U

α ω β ω

β ω α ω

⎡ ⎤= ⎢ ⎥−⎣ ⎦

PMD part

All-Order PMD

CompensationCorrecting Uf to a

frequency-independent matrix

• Wavelength-parallel Jones matrix sensing- Sensing via launch polarization switching and spectral polarimetry data

(no differentiation of polarimetry data)

• Wavelength-by-wavelength Jones matrix correction

Jones space: Full Jones matrix

( ) ( ) ( ) j

f T e U ψ ω

ω ω =( ) ( ) ( )out in E T E ω ω ω =

H. Miao, et, Opt. Lett. 32, 2360 (2007)

l h ll l i S i





Wavelength-Parallel Jones Matrix Sensing

Fast wavelength-parallel polarimeter

for SOP sensing, ms responding time

S. X. Wang, et al, JLT., vol. 24, 3982-3991, 2006

Uf

BroadbandSignal

0° Linear

Input SOP

Spectral

Polarimeter

Uf

RHC

Input SOP

Spectral

Polarimeter

Broadband

Signal

H. Miao, et al. CLEO 2007

• Determines Jones matrix, not PSP vector

• Polarimetry data processed via standard matrix inversion (no differentiation) (+)

- Less susceptible to measurement noise, reduced demands on spectral resolution

• Switching between known polarizations, as in standard Jones matrix methods (-)

difi d l h ll l i S i





Modified Wavelength-Parallel Jones Matrix Sensing

Select two output SOP spectra with angular separation closest to 90°(60°~120°)

Calculate cross product of selected SOP spectra

Associate one selected SOP spectrum, and cross-product spectrum, with 0°and

45°linear input SOP, respectively

Matrix inversion gives U(

ω)=Uf (

ω)Uconst , where Uconst is an unimportant frequency-independent rotation matrix

Compensating Uf (ω) constitutes all-order PMD compensation (plus simple

frequency-independent polarization rotation)

Broadband Signal

with frequency

independent SOPFLC FLC

(0°, 45°) (45°, 90°)

4 SOPsUf

Broadband

Polarimeter

4 Output

SOP Spectra

f const U U U =

H. Miao, et, Opt. Lett. 32, 2360 (2007)

Works for arbitrary input polarization

Processing

algorithm

Ferroelectric liquid crystals

(switchable wave plates)

Jones Matrix Correction





Jones Matrix Correction

* *U

α β

β α

⎡ ⎤= ⎢ ⎥−⎣ ⎦

cos sin

sin cos

j j

j j

e eU

e e

φ ψ

ψ φ

θ θ

θ θ − −

⎡ ⎤= ⎢ ⎥

−⎣ ⎦

Jones matrix of a

0°linear retarder

( )

( )

( )

( )3 12 21

3 12 2

exp 0 exp 0cos sin

0 exp 0 expsin cos

j j jU

j j j

θ θ θ θ

θ θ θ θ

− − −⎡ ⎤ ⎡ ⎤−⎡ ⎤= ⎢ ⎥ ⎢ ⎥⎢ ⎥−⎣ ⎦⎣ ⎦ ⎣ ⎦

Jones matrix of a

0°linear retarder

Jones matrix of a

45°linear retarder

Each frequency sensed and compensated independently

( ) ( )1 2 32 4, , and 2 4θ ϕ ψ π θ θ θ ϕ ψ π = + + = − = − −with

Jones matrix

Jones matrix

inverted

4-layer LCM configuration: 0° 45° 0°90°( )

1 0

0 exp ( ) LCM U

j V θ

⎡ ⎤= ⎢ ⎥

⎣ ⎦Compare matrix of a liquid crystal retarder

(difference leads to extra isotropic phase; taken out with layers 3&4)

Compensation Experiments





Compensation Experiments

Custom 4-layer, 128-pixel liquid crystal modulator array

Pixel spacing: 11.6 GHz

H. Miao, et, Opt. Lett. 32, 2360 (2007)

E i t l R lt (Di t t d SOP S t )





Experimental Results (Distorted SOP Spectra)

800 fs pulse distorted by PMD emulator with mean DGD ~ 5.5 ps

H. Miao, et, Opt. Lett. 32, 2360 (2007)

Distorted and Restored Pulses





Distorted and Restored Pulses

826 fs

828 fs

Intensity cross-correlation measurements

H. Miao, et, Opt. Lett. 32, 2360 (2007)





Extension to Parameters Suitable For DWDM

(e.g., 40 Gb/s systems)

Hyperfine Resolution Wavelength Demux





Hyperfine Resolution Wavelength Demux

Virtually Imaged Phased Array (VIPA)

λ1

λ2

λ3

VIPA

Fiber

Collimator Cylindrical

Lens

Virtual Source Array

• Introduced by Shirasaki, Opt. Lett. (1996)

• Offers high spectral resolution, as in a Fabry-Perot

• But acts as spectral disperer, with large spectral dispersion arising from multiple beam

interference in “side-entrance” etalon geometry

Why?

R r

k x

τ θ

ω

∂ ∂≈

∂ ∂ Bor et al, Opt. Commun. 59, 229 (1985)

Angular dispersion is fundamentally

linked to delay gradient across a

beam.

8-Channel Hyperfine Demux





8 Channel Hyperfine Demux(~700 MHz linewidth, ~3 GHz channel spacing, 50 GHz FSR)

VIPA

Receiving Fiber Array

(output)

Collimator

(input)

Cylindrical LensCylindrical Lenses

Xiao and Weiner, IEEE PTL 17, 372 (2005)

VIPA spectral disperser

(Parts donated by

)

Programmable Hyperfine Resolution VIPA Pulse Shaper





Programmable Hyperfine Resolution VIPA Pulse Shaper

Tunable Dispersion Compensation at 10 Gb/s over 240 km SMF

CYL SLM + Mirror VIPA

λn

λ1

CYL

Circulator

Collimator

B2B

G.-H. Lee, S. Xiao, and A.M. Weiner, OFC 2006 (paper OTHE5); IEEE PTL 18, 1819 (2006)

SMF

240km

uncompensated Compensated (shaper only, no DCF)

Uncompensated

@ 20 km, 40 km

( )( )−∂ψ ω

τ ω =

∂ωApply

quadratic

phase

A.M. Weiner, U.S. patent 6,879,426

PMD Compensation with VIPA Pulse Shaper





PMD Compensation with VIPA Pulse Shaper

Collimator

Cylindrical

Lens

200 GHzVIPA Lens Flipper Mirror LCM

Polarimeter PC

Photo Detector &

Sampling Scope

FLC

PMD

Optical

Pulses

FLC

15 ps

1550.7 nm

50 MHz

~42 ps

mean DGD4-layer LCM

1.6 GHz/pixel

13.8 dB insertion loss

Jones matrix sensing and compensation, as before,but scaled to finer spectral resolution and larger time aperture

H. Miao, et al, OFC 2008 (OThG2)

Pulse widths compatible with 40 Gb/s systems

Compensation Results





Compensation Results

Initial pulse, FLC stable

PMD distorted pulse

FLC switching at 20 Hz

PMD distorted pulse

FLC switching at 2 kHz

Restored pulse

FLC switching at 2 kHz

Continues to work while input polarization is switching

(enables continuous, real-time sensing)

H. Miao, et al,

OFC 2008

(OThG2)





Wavelength-Parallel Polarimetry

Requirement to sense frequency-dependent polarization data

in milliseconds!

A.M. Weiner and X. Wang, U.S. patent 7,116,419

Current Practice: Single-Channel Polarimetry





g y

detector

source

adjustablewave-plates

fixed

polarizer

To achieve frequency (wavelength) resolution:

Multiple polarimeters (expensive)

or

Frequency-swept measurements (slow)

Example:

serial configuration

Fast Wavelength-Parallel Polarization Sensor





g

FLC controller

and data processing

Broadband

optical source

InGasAs

detector

array

Fast switchingFLC retarders

Polarizer

(fixed)Spectral

disperser

(grating/lens)

State 1 State 2 State 1 State 2

Configured for:

• 256 channels

• 0.4 nm (50 GHz) spacing

• < 3° polarization error • < 1 ms read-out time

Wang et al, Opt. Lett. 29, 923 (2004); JLT 24, 3982 (2006)

High Resolution Spectral Polarimeter





High Resolution Spectral Polarimeter

• ~1GHz / pixel spacing

• ~1GHz 3dB resolution

• <1 ms read-out time

• < 3° polarization error

SOP string

spectral SOP

points

10 GHz

WDMchannel

FLCswitching

λ /4 retarder pair

polarizer

0°

50 GHz

VIPAInGaAs line-scan camera

lens

Live 10 Gb/s traffic in AT&T central office

Laboratory tests showing tight

correlation between SOP string length and PMD-

induced power penalty

Now able to resolve polarization variations within 10 Gb/s channel

Wang, Weiner, Boroditsky and Brodsky, IEEE PTL 18, 1753 (2006);

Wang, Weiner, Foo, Bownass, Moyer, O’Sullivan, Birk, and Borodistsky, JLT 24, 4120 (2006)

2D Fast Wavelength Parallel Polarization Sensor





Application to PMD sensing and compensation – Multiple λ’s in single instrument!

High resolution 2D configuration:• 32.8 nm span

• 1500 channels

• 2.8 GHz channel spacing (<20 dB crosstalk)

• 5 ms read-out time (potential)

Grating dispersion direction

V I P A d

i r e c t i o n

1520 nm 1552.8 nm

Wang, Xiao, and Weiner, Opt. Express 13, 2005

2D wavelength demux

50 GHz





All-Order PMD Emulation (Generation)

Traditional PMD Emulators





L. Yan, et. al., JLT, vol. 24, 3992-4005, 2006

Spectral Processor “PMD pulse shaper”

A new approach

Wang et al, IEEE PTL 19, 1203 (2007); Opt. Express 15, 2127 (2007); Miao et al, IEEE PTL, in press.

All-Order Emulation Experimental Setup





F o

r S O P

S e n s i n g

Generate 0°linear and RHC

input SOP for PMD sensing

Müller Matrix Method (MMM) is

used for PMD characterization

4-layer LCM

programmed according

to target PMD (Jones

matrix) profile

Miao et al, IEEE PTL, in press.

All-Order Emulation Experimental Results





PSP

Simple case: emulation of

two concatenated fibers

DGD

Miao et al, IEEE PTL, in press

All-order example: programmedaccording to computer generated

target with 5 ps mean DGD

targetdata

target

data

Independently programmable multi-channel DGD emulation





Broadband source

200 GHz

VIPA

cylindricallens

f=75mmf=500mm

achromaticlensFast scope

12

3 ( – 1 2 d B ) 2-layer

128-elementLCM + mirror

- Hyperfine resolution VIPA shaper

- Accommodates 4 WDM channels at 50 GHz spacing- High-order DGD with fixed PSP (this example)

Frequency dependent DGD profiles CH1

CH2

CH3 CH4

Wang et al, IEEE PTL 19, 1203 (2007); Opt. Express 15, 2127 (2007)

SummaryO i l l i li d ll d PMD





Optical spectral processing applied to all-order PMD

• First reported all-order PMD compensation experiment (sub-ps pulses)

• Wavelength-parallel polarization sensor (parallel sensing at under 1 ms)

• All-order PMD generation

• Extension towards DWDM compatible implementations

• Future challenges, questions, opportunities

• Systems tests

• Endless all-order compensation

• Elucidation of compensation limits, outage probabilities

• 2D spectral disperser geometry with potential for compensation/sensing/emulation of multiple DWDM channels within a single box

H. MiaoM. Akbulut

X. Wang

Li Xu

D.E. LeairdG.-H. Lee

S. Xiao

Z. Jiang

Purdue

P. Miller and L. Mirkin (CRI)M. Boroditsky and M. Brodsky (AT&T)

C .Lin (Avanex)

M. Fejer (Stanford)

Thanks to…

weiner ofc 2008 pmd tutorial final

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