Ultrafast all-optical signal processing using semiconductor optical amplifiers

149 Pages·2017·9.48 MB·English

Ultrafast all-optical signal processing using semiconductor
optical amplifiers
Citation for published version (APA):
Li, Z. (2007). Ultrafast all-optical signal processing using semiconductor optical amplifiers. [Phd Thesis 1
(Research TU/e / Graduation TU/e), Electrical Engineering]. Technische Universiteit Eindhoven.
https://doi.org/10.6100/IR626974
DOI:
10.6100/IR626974
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Published: 01/01/2007
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Ultrafast all-optical signal processing
using semiconductor optical ampli(cid:12)ers
Zhonggui Li

Ultrafast all-optical signal processing using
semiconductor optical ampli(cid:12)ers
PROEFSCHRIFT
ter verkrijgingvan de graad van doctor aan de
Technische Universiteit Eindhoven, op gezag van de
Rector Magni(cid:12)cus, prof.dr.ir. C.J. van Duijn, voor een
commissie aangewezendoor het College voor
Promoties in het openbaar te verdedigen
op dinsdag 12 juni 2007 om 16.00 uur
door
Zhonggui Li
geboren te Sichuan, China
Dit proefschrift is goedgekeurd door de promotor:
prof.ir. G.D. Khoe
en
prof.dr. D. Lenstra
Copromotor:
dr.ir. H.J.S. Dorren
CIP-DATA LIBRARY TECHNISCHE UNIVERSITEIT EINDHOVEN
Li, Zhonggui
Ultrafast all-optical signal processing using semiconductor optical ampli(cid:12)ers / by
Zhonggui Li - Eindhoven : Technische Universiteit Eindhoven, 2007.
Proefschrift.- ISBN 978-90-386-1534-9
NUR 959
Trefw.: optische telecommunicatie / halfgeleiderversterkers/ optische
signaalverwerking.
Subject headings: optical (cid:12)bre communication / semiconductor optical ampli(cid:12)ers
/ optical information processing.
Copyright c 2007by Zhonggui Li
(cid:13)
Allrightsreserved.Nopartofthispublicationmaybereproduced,storedin are-
trievalsystem,ortransmittedinanyformorbyanymeanswithoutthe priorwrit-
ten consent of the author.
Typeset using LATEX, printed in The Netherlands
Summary
Ultrafast all-optical signal processing us-
ing semiconductor optical ampli(cid:12)ers
As the bit rate of one wavelength channel and the number of channels keep
increasing in the telecommunication networks thanks to the advancement of op-
tical transmission technologies, switching is experiencing the transition from the
electrical domain to the optical domain. All-optical signal processing, including
wavelengthconversion,opticallogicgatesandsignalregeneration,etc,isoneofthe
mostimportantenablingtechnolgiestorealizeopticalswitching,includingoptical
circuit switching, optical burst switching and optical packet switching.
Semiconductoropticalampli(cid:12)ers(SOAs)areverypromisinginall-opticalsignal
processingbecausetheyarecompact,easytomanufactureandpowere(cid:14)cient. Itis
thereforeveryimportanttodevelopnumericalmodelsfortheSOAstounderstand
their behaviourin di(cid:11)erent system con(cid:12)gurations,especiallywhen the interacting
pulsedurationbecomesshorterandshorterwith increasingbitrate,whereseveral
e(cid:11)ects that are neglected in previous models have to be accounted for.
To investigate high-speed SOA-based all-optical signal processing systems, in
this thesis we develop a comprehensive model, which includes both inter- and
intra-bandcarrierdynamics,gaindispersionandgroupvelocitydispersion,inthis
thesis. Polarization dependent e(cid:11)ects can also be taken into account through
introducing an imbalance factor f. Finite-di(cid:11)erence beam propagation method is
employed to solve the numerical model.
Mode-locking lasers o(cid:11)er a lot of applications in all-optical signal processing
systems. Inthisthesisweinvestigateanovelmode-lockedlaserbasedonnonlinear
polarization rotation in an SOA. The pulse narrowing process is demonstrated
numerically, achieving good agreement with our experimental results. The pulse
performance is largely determined by the ultrafast SOA gain dynamics and the
cavity dispersion. The laser can produce a pulse train of sub-picosecond pulse
width at a repetition rate of 28 GHz, which is limited by the carrier lifetime, for
a moderate SOA currentlevel. For higher currentsinstabilities occurin the laser.
vi
OneofthedrawbacksoftheSOA-baseddevicesistherelativelylonggainrecov-
ery time which results in strong pattern e(cid:11)ects for high bit rate operaion. In this
thesis we extensively investigate a very high bit rate wavelength converter based
on a single SOA and an optical bandpass (cid:12)lter. The enhancement in operation
speed is based on (cid:12)ltering an amplitude- and phase-modulated signal. We study
the underlying working principle and perform detailed analysis of the high-speed
wavelengthconverter,whichleadstooptimizationrulesforhigh-speedSOA-based
wavelengthconversion. Moreover,bothinvertedandnon-invertedwavelengthcon-
version at much higher bit rate(1 T b/s), is also predicted. Furthermore, genetic
algorithm is introduced in the optimization of the transfer function of the OBF
following the SOA. Through optimization, eye opening of more than 33 dB is
shown for non-inverted wavelength conversion. The optimized (cid:12)lter can be ex-
perimentally implemented through a combination of asymmetric Mach-Zehnder
interferometer and a Gaussian (cid:12)lter.
Enlightenedbytheworkingprincipleofthewavelengthconverter,weproposed
and demonstrated experimentally a novel optical logic gate with a very simple
structure: an SOA followed by an OBF. This logic gate can realize AND, OR
and XOR gate functions based on the same setup but with di(cid:11)erent operation
conditions. This novel device can be integrated.
Contents
1 Introduction 1
1.1 Switching: From electrical to optical . . . . . . . . . . . . . . . . . 1
1.2 All-optical signal processing . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 Di(cid:11)erent materials . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.2 SOA-based all-optical signal processing: State of the art . . 5
1.2.3 Motivation of the work. . . . . . . . . . . . . . . . . . . . . 6
1.3 Contributions of this thesis . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Outline of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Numerical model including ultrafast carrier dynamics 9
2.1 Overview of the SOA models . . . . . . . . . . . . . . . . . . . . . 9
2.1.1 Carrier dynamics . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2 Field propagation. . . . . . . . . . . . . . . . . . . . . . . . 12
2.2 The SOA model used in this thesis . . . . . . . . . . . . . . . . . . 14
2.2.1 Basic Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.2 Extended model . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3 Numerical implementation . . . . . . . . . . . . . . . . . . . . . . . 21
2.3.1 Solving carrier equations. . . . . . . . . . . . . . . . . . . . 21
2.3.2 Solving (cid:12)eld equations . . . . . . . . . . . . . . . . . . . . . 22
2.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3 Mode-lockingbasedonnonlinearpolarizationrotationinanSOA 25
3.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.1.1 Nonlinear polarization rotation in the SOA . . . . . . . . . 25
3.1.2 Mode-locking . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2 Working principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.3 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.3.1 System model . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.3.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.4 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
viii CONTENTS
4 Performanceanalysisof(cid:12)lter-assistedhighspeedwavelengthcon-
version 47
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.1.1 All-optical wavelength conversion . . . . . . . . . . . . . . . 47
4.1.2 SOA-based AOWC: Advantages and Challenges. . . . . . . 48
4.2 Working principle of (cid:12)lter-assisted wavelength converter . . . . . . 50
4.2.1 History in this (cid:12)eld. . . . . . . . . . . . . . . . . . . . . . . 50
4.2.2 Working principle . . . . . . . . . . . . . . . . . . . . . . . 51
4.3 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.3.1 Experimental results at 160 Gb/s . . . . . . . . . . . . . . . 54
4.3.2 Experimental results at 320 Gb/s . . . . . . . . . . . . . . . 56
4.4 Simulation results . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4.1 Previous work. . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4.2 Simulation Con(cid:12)guration . . . . . . . . . . . . . . . . . . . 60
Filter model. . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Performancemetrics of the output signal . . . . . . . . . . 62
Characteristics of the investigated SOA . . . . . . . . . . . 63
Gain dispersion . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.4.3 Simulation results at 160 Gb/s . . . . . . . . . . . . . . . . 65
Output from detuned OBF . . . . . . . . . . . . . . . . . . 65
Pump pulse energy dependence . . . . . . . . . . . . . . . . 66
Probe power dependence. . . . . . . . . . . . . . . . . . . . 68
Linewidth enhancement factor dependence. . . . . . . . . . 70
Injection current dependence . . . . . . . . . . . . . . . . . 73
4.4.4 Simulation results at 320 Gb/s . . . . . . . . . . . . . . . . 76
4.4.5 Simulation results at 1 Tb/s. . . . . . . . . . . . . . . . . . 77
4.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.5.1 Di(cid:11)erentation function of the OBF . . . . . . . . . . . . . . 81
4.5.2 In(cid:13)uence of ASE . . . . . . . . . . . . . . . . . . . . . . . . 82
4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5 Filter optimization for wavelength converter based on Genetic
Algorithms 85
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.1.1 Problem statement . . . . . . . . . . . . . . . . . . . . . . . 85
5.1.2 Search algorithms . . . . . . . . . . . . . . . . . . . . . . . 86
5.1.3 Genetic Algorithms. . . . . . . . . . . . . . . . . . . . . . . 87
5.2 Simulation con(cid:12)gurations . . . . . . . . . . . . . . . . . . . . . . . 88
5.3 Optimization results . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5.3.1 Optimum (cid:12)lters. . . . . . . . . . . . . . . . . . . . . . . . . 89
5.3.2 Optimum (cid:12)lter tolerance against (cid:12)lter parameters . . . . . 92
5.3.3 Optimum(cid:12)ltertoleranceagainst(cid:11)andSOAoperationcon-
dition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.4 Implementation consideration . . . . . . . . . . . . . . . . . . . . . 94
CONTENTS ix
5.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6 A novel all-optical logic gate based on an SOA and an optical
bandpass (cid:12)lter 99
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
6.2 System concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
6.3 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7 Conclusions and recommendations 107
References 111
A List of Abbreviations 125
B List of Publications 127
C Samenvatting 133
D Acknowledgements 135
E Curriculum Vit(cid:26) 137