microwave photonics applications of stimulated brillouin scattering dr. avi zadok, school of...

Microwave Photonics Microwave Photonics Applications of Stimulated Applications of Stimulated

Brillouin ScatteringBrillouin Scattering

Dr. Avi ZadokDr. Avi Zadok, , School of Engineering, Bar-Ilan UniversitySchool of Engineering, Bar-Ilan University +972-3-5318882+972-3-5318882 [email protected]@eng.biu.ac.il www.eng.biu.ac.il/~zadoka/www.eng.biu.ac.il/~zadoka/

Together with: Together with: Prof. Moshe Tur, Prof. Avishay Eyal, Dr. Oded Raz, Elad Prof. Moshe Tur, Prof. Avishay Eyal, Dr. Oded Raz, Elad

Zilka, and Yair Peled, School of Electrical Engineering, Zilka, and Yair Peled, School of Electrical Engineering,

Tel-Aviv UniversityTel-Aviv University

BIU – UV workshop, 13-14/4/2010BIU – UV workshop, 13-14/4/2010 Dr. Avi ZadokDr. Avi Zadok 22

OutlineOutline Broadband Stimulated Brillouin Scattering Processes in Broadband Stimulated Brillouin Scattering Processes in

Optical FibersOptical Fibers

Variable (“slow light”) group delay of waveformsVariable (“slow light”) group delay of waveforms

Data pulsesData pulses

Analog, radar waveformsAnalog, radar waveforms

Single-sideband modulation formatSingle-sideband modulation format

Ultra-wideband noise-based transmissionUltra-wideband noise-based transmission


Stimulated Brillouin Scattering Stimulated Brillouin Scattering

Strict phase matching conditions: Strict phase matching conditions: pp - - ss = = B B (~2(~211 GHz)11 GHz)


Characteristics of SBSCharacteristics of SBS Low threshold in standard fibers (few mW)Low threshold in standard fibers (few mW) Simple and robustSimple and robust Detrimental effect in optical communication: restricts the Detrimental effect in optical communication: restricts the

transmitted powertransmitted power Gain coefficient is of Lorenzian lineshape: Gain coefficient is of Lorenzian lineshape:

Ultra-narrow linewidth for CW pump: ~ 30 MHz only!Ultra-narrow linewidth for CW pump: ~ 30 MHz only! Objective: utilize SBS for all-optical signal Objective: utilize SBS for all-optical signal

processingprocessing

2 2

0 0

1 21 2

p p

sBs p B B

g A g Ag

jj


SBS with Broadened PumpSBS with Broadened Pump

SignalPump1p2p3p


SBS with Broadened PumpSBS with Broadened Pump

Broadened Pump: Magnitude gain is proportional to Broadened Pump: Magnitude gain is proportional to the pump spectrumthe pump spectrum

Phase response related to the magnitude gain Phase response related to the magnitude gain through the Kramers – Kronig Relations:through the Kramers – Kronig Relations:

'

'

'Re'2Im

22

d

gg

s

s

Calculation of SBS response for arbitrary pumpCalculation of SBS response for arbitrary pump


Pump Broadening Via Direct Pump Broadening Via Direct ModulationModulation

Shalom et. al, JQE, Vol. 34 pp. 1816-1824, 1998

Thermalchirp

Adiabaticchirp


Pump spectrum measurementPump spectrum measurement

tiT

Ttiiti N

5.1

0

mod1

SimulationSimulation Heterodyne measurementHeterodyne measurement

ns320T

mA11i

mA6.12 tiN

Synthesized pumpSynthesized pump

Modulation:Modulation:

MHz20NB

mA800 i


““Slow Light”Slow Light” Optically-controlled, variable group delayOptically-controlled, variable group delay Sharp phase delay variations, often Sharp phase delay variations, often

associated with narrow-band gain / absorptionassociated with narrow-band gain / absorption Control through non-linear interactionsControl through non-linear interactions

Spectral gain Spectral phase delay


Pump spectrum synthesisPump spectrum synthesis

-3 -2 -1 0 1 2 30

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Re

lativ

e g

ain

Normalized frequency offset-3 -2 -1 0 1 2 3

-1.5

-1

-0.5

0

0.5

1

1.5

Normalized frequency offset

Ph

ase

re

spo

nse

[arb

.]

gIm 2Re BpEg

Sharp spectral edges of pump spectrum: Sharp spectral edges of pump spectrum: enhancement of delay–bandwidth product.enhancement of delay–bandwidth product.


Measurement of SBS gain and Measurement of SBS gain and phase responsephase response

Optical BPF

EDFA

Tunable Laser SSB Modulator

Arbitrary Waveform Generator

EDFA

DSFNetwork Analyzer

Polarization Controller

Isolator

Variable Attenuator

Detector

Pump

Pump

Probe

Loayssa et. al, IEE Proc. Optoelectron., Vol. 148 pp. 143-148, 2001


SBS Slow and Fast LightSBS Slow and Fast Light SBS amplification accompanied by steep gradients of the SBS amplification accompanied by steep gradients of the

signal phase as a function of frequency – group delay signal phase as a function of frequency – group delay

-3 -2 -1 0 1 2 30

10

20

Ga

in [d

B]

-3 -2 -1 0 1 2 3-2

0

2Frequency offset [GHz]

Ph

ase

[ra

d]


Delay of Isolated PulsesDelay of Isolated Pulses SBS amplification accompanied by steep gradients of the SBS amplification accompanied by steep gradients of the

signal phase as a function of frequency – group delay signal phase as a function of frequency – group delay

A. Zadok et al., Opt. Express 14, 8498, 2006


Delay of 5Gb/s PRBS Delay of 5Gb/s PRBS Output NRZ eye diagram: Synthesized modulation, 22dBm, 120ps delay

First demonstration of high-rate PRBS delay using SBS

BER for 80, 100, 120ps delay: <10-9, 10-8, 410-6

Zadok et. al, Opt. Express, Vol. 14 pp. 8498-8505, 2006


5Gb/s PRBS: Delay Enhancement5Gb/s PRBS: Delay Enhancement

Synthesized pump modulation: 25-40% longer delays

6 7 8 9 10 11 12 130

20

40

60

80

100

120

140

PRBS signal power gain [dB]

Me

asu

red

PR

BS

de

lay

[pS

]SynthesizedMod.

Random Mod.


True Time Delay (TTD) in phased True Time Delay (TTD) in phased array antennasarray antennas

True TimeDelay

DD D DD D DD

Beam-stirring using variable delay between elements Beam-stirring using variable delay between elements Large bandwidth: group delay instead of phase delayLarge bandwidth: group delay instead of phase delay Low distortion necessaryLow distortion necessary


LFM “impulse response” metricsLFM “impulse response” metrics

PSLPSLMain lobeMain lobewidth ~ 1/Bwidth ~ 1/B

elsewhere

LFM

lobemain

LFM dhdh22

ISLR


Delay of LFM signalsDelay of LFM signals

10 15 20 25

100

200

300

SBS power gain [dB]

De

lay

[ps]

10 12 14 16 18 20 2250

100

150

SBS power gain [dB]

De

lay

[ps]

20km DSF20km DSF

3.5km HNLF:3.5km HNLF:

‘‘+’: VNA+’: VNA

‘‘’’: LFM: LFM

Zadok et. al, IEEE PTL, Vol. 19, pp. 462-464, 2007

0

sin sinNd N Nc c f

50 GHz system: ~ 10 elements, 90°


Measured impulse responseMeasured impulse response

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

x 10-5

-150

-100

-50

0Input pulse

[Sec]

[dB

]

-500 -250 0 250 500-5

-3

-1

1

RF frequency [MHz]

ph

ase

[ra

d]

-30 -20 -10 0 10 20 30-60

-40

-20

0

Time [ns]

Re

spo

nse

[dB

] μs20T

1GHzB

Pump power:Pump power:

20dBm20dBm

Width broad: <1%Width broad: <1%

PSL: < -26dBPSL: < -26dB

ISLR: > 21dBISLR: > 21dB

Delay: 230psDelay: 230ps


SSB modulation - noiseSSB modulation - noiseHeterodyne spectral measurement of LFM-modulated signal:Heterodyne spectral measurement of LFM-modulated signal:

One side band amplified by SBS. One side band amplified by SBS. No harmonicsNo harmonics. . NF ~ 150*. NF ~ 150*.

Pump offPump off

Pump onPump on

μs2T

1GHzB

Pump 20dBmPump 20dBm

-4 -3 -2 -1 0 1 2 3 4-110

-100

-90

-80

-70

-60

-50

Optical frequency Offset [GHz]

Pro

be p

ower

spe

ctra

l den

sity

[dB

]

NoiseNoise

*: Olsson et. al, JLT, Vol. 5

pp. 147-153, 1987

A. Zadok et al. J. Lightwave Technol. 25, 2168-2174 (2007)


Impulse response of SSB Impulse response of SSB modulated LFM signalmodulated LFM signal

-40 -30 -20 -10 0 10 20 30 40-60

-50

-40

-30

-20

-10

0Im

puls

e re

spon

se [d

B]

Time [ns]

Simulated noiseIdealMeasurement


Ultra-wideband waveform Ultra-wideband waveform generationgeneration

UWB impulse radio: several GHz-wide, no sine-wave UWB impulse radio: several GHz-wide, no sine-wave carriers, low power spectral densitycarriers, low power spectral density

Applications: indoor wireless communication, imaging Applications: indoor wireless communication, imaging systems, vehicular radar systems. systems, vehicular radar systems.


UWB noise-based communicationUWB noise-based communication

Slow-rate modulation of broadband noise with carefully Slow-rate modulation of broadband noise with carefully controlled power spectral densitycontrolled power spectral density

Alternative to tailored, short pulses.Alternative to tailored, short pulses.


Experimental resultsExperimental resultsBrillouin pump spectrum: Generated noise spectrum:

1.1 GHz bandwidth1.1 GHz bandwidth

Y. Peled, M. Tur and A. Zadok, Paper NTuC16, Nonlinear Photonics 2010


Experimental results Cntd.Experimental results Cntd.8 Mb/s transmission (no reference) Correlation properties

Q = 10Q = 10



Experimental results Cntd.Experimental results Cntd.4 Mb/s transmission (with reference) Decoded waveform

Q = 5Q = 5

1 2 3 4 5-0.5

0

0.5

Time [micro-sec]1 2 3 4 5

-5

0

5

10

15

20

25

Time [micro-sec]


microwave photonics applications of stimulated brillouin scattering dr. avi zadok, school of...

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