Semiconductor Laser Engineering, Reliability and Diagnostics

This reference book provides a fully integrated novel approachto the development of high-power, single-transverse mode,edge-emitting diode lasers by addressing the complementary topicsof device engineering, reliability engineering and devicediagnostics in the same book, and thus closes the gap in thecurrent book literature.

Diode laser fundamentals are discussed, followed by an elaboratediscussion of problem-oriented design guidelines and techniques,and by a systematic treatment of the origins of laser degradationand a thorough exploration of the engineering means to enhance theoptical strength of the laser. Stability criteria of critical lasercharacteristics and key laser robustness factors are discussedalong with clear design considerations in the context ofreliability engineering approaches and models, and typical programsfor reliability tests and laser product qualifications. Novel,advanced diagnostic methods are reviewed to discuss, for the firsttime in detail in book literature, performance- andreliability-impacting factors such as temperature, stress andmaterial instabilities.

Further key features include: * practical design guidelines that consider also reliabilityrelated effects, key laser robustness factors, basic laserfabrication and packaging issues; * detailed discussion of diagnostic investigations of diodelasers, the fundamentals of the applied approaches and techniques,many of them pioneered by the author to be fit-for-purpose andnovel in the application; * systematic insight into laser degradation modes such ascatastrophic optical damage, and a wide range of technologies toincrease the optical strength of diode lasers; * coverage of basic concepts and techniques of laser reliabilityengineering with details on a standard commercial high power laserreliability test program.

Semiconductor Laser Engineering, Reliability andDiagnostics reflects the extensive expertise of the author inthe diode laser field both as a top scientific researcher as wellas a key developer of high-power highly reliable devices. Withinvaluable practical advice, this new reference book is suited topractising researchers in diode laser technologies, and topostgraduate engineering students.

Dr. Peter W. Epperlein is Technology Consultant with his ownsemiconductor technology consulting businessPwe-PhotonicsElectronics-IssueResolution in the UK. He looks backat a thirty years career in cutting edge photonics and electronicsindustries with focus on emerging technologies, both in global andstart-up companies, including IBM, Hewlett-Packard, AgilentTechnologies, Philips/NXP, Essient Photonics and IBM/JDSU LaserEnterprise. He holds Pre-Dipl. (B.Sc.), Dipl. Phys. (M.Sc.) and Dr.rer. nat. (Ph.D.) degrees in physics, magna cum laude, from theUniversity of Stuttgart, Germany.

Dr. Epperlein is an internationally recognized expert incompound semiconductor and diode laser technologies. He hasaccomplished R&D in many device areas such as semiconductorlasers, LEDs, optical modulators, quantum well devices, resonanttunneling devices, FETs, and superconducting tunnel junctions andintegrated circuits. His pioneering work on sophisticateddiagnostic research has led to many world s first reports andhas been adopted by other researchers in academia and industry. Heauthored more than seventy peer-reviewed journal papers, publishedmore than ten invention disclosures in the IBM Technical DisclosureBulletin, has served as reviewer of numerous proposals forpublication in technical journals, and has won five IBM ResearchDivision Awards. His key achievements include the design andfabrication of high-power, highly reliable, single mode diodelasers.

Book Reviews Semiconductor Laser Engineering, Reliability andDiagnostics: A Practical Approach to High Power and Single ModeDevices . By Peter W. Epperlein Prof. em. Dr. Heinz Jackel, High Speed Electronics andPhotonics, Swiss Federal Institute of Technology ETHZurich, Switzerland

The book Semiconductor Laser Engineering, Reliabilityand Diagnostics by Dr. P.W. Epperlein is a landmark in therecent literature on semiconductor lasers because it fills alongstanding gap between many excellent books on laser theory andthe complex and challenging endeavor to fabricate these devicesreproducibly and reliably in an industrial, real worldenvironment.

Having worked myself in the early research and development ofhigh power semiconductor lasers, I appreciate the competent,complete and skillful presentation of these three highlyinterrelated topics, where small effects have dramatic consequenceson the success of a final product, on the ultimate performance andon the stringent reliability requirements, which are the name ofthe game.

As the title suggests the author addresses three tightlyinterwoven and critical topics of state-of-the-art power laserresearch. The three parts are: device and mode stabilityengineering (chapter 1, 2), reliability mechanisms and reliabilityassessment strategies (chapter 3, 4, 5, 6) and finally material anddevice diagnostics (chapter 7, 8, 9) all treated with a strongfocus on the implementation. This emphasis on the complex practicalaspects for a large-scale power laser fabrication is a truehighlight of the book.

The subtle interplay between laser design, reliabilitystrategies, advanced failure analysis and characterizationtechniques are elaborated in a very rigorous and scientific wayusing a very clear and easy to read representation of the complexinterrelation of the three major topics. I will abstain from tryingto provide a complete account of all the topics but mainlyconcentrate on the numerous highlights.

The first part 1 Laser Engineering is dividedin two chapters on basic electronic-optical, structural, materialand resonator laser engineering on the one side, and on single modecontrol and stability at very high, still reliable power-levelswith the trade-off between mirror damage, single mode stability onthe other side. To round up the picture less well-known conceptsand the state-of-the-art of large-area lasers, which can be forcedinto single-mode operation, are reviewed carefully. The subtle andcomplex interplay, which is challenging to optimize for a designfor reliability and low stress as a major boundary condition iscrucial for the design. The section gives a rather complete andwell-referenced account of all relevant aspects, relations andtrade-offs for understanding the rest of the book.

The completeness of the presentation on power laser diodedesign based on basic physical and plausible arguments is mainlybased on analytic mathematical relations as well as experimentsproviding a new and well-balanced addition for the power diodelaser literature in particular. Modern 2D self-consistentelectro-optical laser modeling including carrier hole burning andthermal effects this is important because the weak opticalguiding and gain-discrimination depend critically on rather smallquantities and effects, which are difficult to optimizeexperimentally is used in the book for simulation results,but is not treated separately.

The novel and really original, gap-filling bulkof the book is elaborated by the author in a very clear way in thefollowing four chapters in the part 2 LaserReliability on laser degradation physics and mirror designand passivation at high power, followed then by two veryapplication oriented chapters on reliability design engineering andpractical reliability strategies and implementation procedures.This original combination of integral design and reliabilityaspects which are mostly neglected in standardliterature is certainly a major plus of this book. I likedthis second section as a whole, because it provides excellentinsights in degradation physics on a high level and combines it inan interesting and skillful way with the less glamorous (unfortunately) but highly relevantreliability science and testing strategies, which is particularlyimportant for devices operating at extreme optical stresses withchallenging lifetime requirements in a real wordenvironment.

Finally, the last part 3 Laser Diagnostics comprising three chapters, is devoted mainly to advancedexperimental diagnostics techniques for material integrity,mechanical stress, deep level defects, various dynamic laserdegradation effects, surface- and interface quality, and mostimportantly heating and disordering of mirrors and mirror coatings.The topics of characterization techniques comprising micro-Raman-and micro-thermoreflectance-probing, 2K photoluminescencespectroscopy, micro-electroluminescence and photoluminescencescanning, and deep-level-transient spectroscopy have been pioneeredby the author for the specific applications over many yearsguaranteeing many competent and well represented insights. Thesetechniques are brilliantly discussed and the informationdistributed in many articles by the author has been successfullyunified in a book form.

In my personal judgment and liking, I consider the parts 2and 3 on reliability and diagnostics as the most valuable and truenovel contribution of the book, which in combination with theextremely well-covered laser design of part 1 clearly fill the gapin the current diode laser literature, which in this detail hascertainly been neglected in the past.

In summary, I can highly recommend this excellent,well-organized and clearly written book to readers who are alreadyfamiliar with basic diode laser theory and who are active in theacademic and industrial fabrication and characterization ofsemiconductor lasers. Due to its completeness, it also serves as anexcellent reference of the current state-of-the-art in reliabilityengineering and device and material diagnostics.

Needless to mention that the quality of the book, itsrepresentations and methodical structure meet the highestexpectation and are certainly a tribute from the long and broadexperience of the author in academic laser science and theindustrial commercialization of high power diode lasers.

In my opinion, this book was a pleasure to read and due toits quality and relevance deserves a large audience in the powerdiode laser community!

Prof. em. Dr. Heinz Jackel, High Speed Electronicsand Photonics, Swiss Federal Institute of Technology ETHZurich, Switzerland

June 16, 2013

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Semiconductor Laser Engineering, Reliability andDiagnostics: A Practical Approach to High Power and Single ModeDevices . By Peter W. Epperlein

Dr. Chung-en Zah, Research Director,Semiconductor Technologies Research, S&T Division,Corning Incorporate, Corning NY, USA

This book covers for the first time the three closelyinterrelated key laser areas of engineering (design), reliabilityand diagnostics in one book, written by the well-known practitionerin cutting-edge optoelectronics industries, Dr. Peter W. Epperlein.The book closes the gap in the current book literature and is thusa unique and excellent example of how to merge design, reliabilityand diagnostics aspects in a very professional, profound andcomplete manner. All physical and technological principles,concepts and practical aspects required for developing andfabricating highly-reliable high-power single-mode laser productsare precisely specified and skilfully formulated along with all thenecessary equations, figures, tables and worked-out examples makingit easy to follow through the nine chapters. Hence, this uniquebook is a milestone in the diode laser literature and is anexcellent reference book not only for diode laser researchers andengineers, but also diode laser users.

The engineering part starts with a very informative andclear, well-presented account of all necessary basic diode lasertypes, principles, parameters and characteristics for an easy andquick understanding of laser functionality within the context ofthe book. Along with an elaborate and broad discussion of relevantlaser material systems, applications, typical output powers,power-limiting factors and reliability tradeoffs, basic fabricationand packaging technologies, this excellent introductory section iswell suited to become quickly and easily familiar with practicalaspects and issues of diode laser technologies. Of specialimportance and high usefulness is the first analytic andquantitative discussion in a book on issues of coupling laser powerinto optical single mode fibers. The second section discusses in awell-balanced, competent and skilful way waveguide topics such asbasic high-power design approaches, transverse vertical and lateralwaveguide concepts, stability of the fundamental transverse lateralmode and fundamental mode waveguide optimization techniques byconsidering detrimental effects such as heating, carrier injection,spatial hole burning, lateral current spreading and gain profilevariations. Less well-known approaches to force large-area lasersinto a single mode operation are well-identified and carefullydiscussed in depth and breadth. All these topics are elaborated ina very complete, rigorous and scientific way and are clearlyarticulated and easy to read. In particular, the book works out thecomplex interaction between the many different effects to optimizehigh-power single-mode performance at ultimate reliability and thusis of great benefit to every researcher and engineer engaged inthis diode laser field.

Another novelty and highlight is, for the first time ever inbook form, a comprehensive yet concise discussion of diode laserreliability related issues. These are elaborated in four distinctchapters comprising laser degradation physics and modes, opticalstrength enhancement approaches including mirrorpassivation/coating and non-absorbing mirror technologies, followedby two highly relevant product-oriented chapters on reliabilitydesign engineering concepts and techniques and an elaboratereliability test plan for laser chip and module productqualification. This original and novel approach to link laserdesign to reliability aspects and requirements provides both, mostuseful insight into degradation processes such as catastrophicoptical mirror damage on a microscopic scale, and a wide selectionof effective remedial actions. These accounts, which are of highestsignificance for lasers operating at the optical stress limit dueto extremely high output power densities and most demandinglifetime requirements are very professionally prepared anddiscussed in an interesting, coherent and skilfulmanner.

The diagnostics part, consisting of three very elaboratechapters, is most unique and novel with respect to other diodelaser books. It discusses for the first time ever on a very highlevel and in a competent way studies on material integrity,impurity trapping effects, mirror and cavity temperatures, surface-and interface quality, mirror facet disorder effects, mechanicalstress and facet coating instability, and diverse laser temperatureeffects, dynamic laser degradation effects and mirror temperaturemaps. Of highest significance to design, performance andreliability are the various correlations established between laserdevice and material parameters. The most different andsophisticated experiments, carried out by the author at micrometerspatial resolutions and at temperatures as low as 2K, providehighly valuable insights into laser and material qualityparameters, and reveal for the first time the origins of high powerlimitations on an atomic scale due to local heating effects anddeep level defects. It is of great benefit, that the experimentaltechniques such as Raman spectroscopy, various luminescencetechniques, thermoreflectance and deep-level transientspectroscopy, pioneered by the author for the specific experimentson lasers, are discussed with great expertise in depth and breadth,and the numerous paper articles published by the author are nowrepresented in this book.

The book has an elaborate table of contents and index, whichare very useful, over 200 illustrative figures and tables, andextensive lists of references to all technical topics at the end ofeach of the nine chapters, which make it easy to follow from coverto cover or by jumping in at random areas of special interest.Moreover, experimental and theoretical concepts are alwaysillustrated by practical examples and data.

I can highly recommend this extremely relevant,well-structured and well-formulated book to all practisingresearchers in industrial and academic diode laser R&Denvironments and to post-graduate engineering students interestedin the actual problems of designing, manufacturing, testing,characterising and qualifying diode lasers. Due to its completenessand novel approach to combine design, reliability and diagnosticsin the same book, it can serve as an ideal reference book as well,and it deserves to be welcomed wordwide by the addressedaudience.

Dr. Chung-en Zah, Research Director, SemiconductorTechnologies Research, S&T Division, Corning Incorporate,Corning NY, USA

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Semiconductor Laser Engineering, Reliability andDiagnostics: A Practical Approach to High Power and Single ModeDevices . By Peter W. Epperlein

Cordinatore Prof. Lorenzo Pavesi, UNIVERSITA DEGLI STUDIDI TRENTO, Dipartimento di Fisica / Laboratorio di Nanoscienze

This book represents a well thought description of threefundamental aspects of laser technology: the functioningprinciples, the reliability and the diagnostics. From this point ofview, and, as far as I know, this is a unique example of a bookwhere all these aspects are merged together resulting in awell-balanced presentation. This helps the reader to move with easebetween different concepts since they are presented in a coherentmanner and with the same terminology, symbols anddefinitions.

The book reads well. Despite the subtitle indicates that itis a practical approach, the book is also correct from a formalpoint of view and presents the necessary equations and derivationsto understand both the physical mechanisms and the practicalitiesvia a set of useful formulas. In addition, there is the moreimportant aspect of many real-life examples of how a laser isactually manufactured and which the relevant parameters thatdetermine its behaviour are. It impresses the amounts ofinformation that are given in the book: this would be more typicalof a thick handbook on semiconductor laser than of an agile book.Dr. Epperlein was able to identify the most important concepts andto present them in a clear though concise way.

I am teaching a course on Optoelectronics and I'm going toadvise students to refer to this book, because it has all thenecessary concepts and derivations for a systematic understandingof semiconductor lasers with many worked-out examples, which willhelp the student to grasp the actual problems of designing,manufacturing, testing and using semiconductor lasers. All thevarious concepts are joined to very useful figures, which, ifprovided to instructors as files, can be a useful add-on for theuse of the book as text for teaching. Concepts are always detailedwith numbers to give a feeling of their practical use.

In conclusion, I do find the book suitable for my teachingduties and will refer it to my students.

Prof. Dr. Lorenzo Pavesi, Head of the Department ofPhysics, Head of the Nanoscience Laboratory, University of Trento,Italy 31 May 2013

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Semiconductor Laser Engineering, Reliability andDiagnostics: A Practical Approach to High Power and Single ModeDevices . By Peter W. Epperlein

Robert W. Herrick, Ph.D., Senior Component ReliabilityEngineer, Intel Corp., Santa Clara, California, USA Dr. Epperlein has done the semiconductor laser community agreat service, by releasing the most complete book on the market onthe practical issues of how to make reliable semiconductorlasers.

While dozens of books have been written over the past coupleof decades on semiconductor laser design, only a handful have beenwritten on semiconductor laser reliability. Prior to the release ofthis book, perhaps 40% of the material could be obtained elsewhereby combining five books: one on laser design, one on laserreliability, one on reliability calculations, and a couple of laserreview books. Another 40% could be pieced together bycollecting 50 -100 papers on the subjects of laser design, laserfabrication, characterization, and reliability. The remaining 20%have not previously been covered in any comprehensive way. Only the introductory material in the first half of the firstchapter has good coverage elsewhere. The large majority of theknowledge in this book is generally held as tradesecret by those with the expertise in the field, and most ofthose in the know are not free to discuss. The author was fortunateenough to work for the first half of his career in the IBM researchlabs, with access to unparalleled resources, and the ability topublish his work without trade secret restrictions. The results arestill at the cutting edge of our understanding of semiconductorlaser reliability today, and go well beyond the empirical black box approach many use of try everything,and see what works. The author did a fine job of pullingtogether material from many disparate fields.

Dr. Epperlein has particular expertise in high power singlemode semiconductor lasers, and those working on those type oflasers will be especially interested in this book, as there hasnever been a book published on the fabrication and qualification ofsuch lasers before. But those in almost any field ofsemiconductor lasers will learn items of interest about devicedesign, fabrication, reliability, and characterization. Unlike most other books, which intend to convey the scientificfindings or past work of the author, this one is written more as a how to manual, which should make it more accessibleand useful to development engineers and researchers in the field.It also has over 200 figures, which make it easier to follow. As with many books of this type, it is not necessary to read itfrom cover-to-cover; it is best skimmed, with deep diving into anyareas of special interest to the reader. The book isremarkable also for how comprehensive it is even expertswill discover something new and useful.

Dr. Epperlein s book is an essential read for anyonelooking to develop semiconductor lasers for anything other thanpure research use, and I give it my highest recommendation. Robert W. Herrick, Ph.D., Senior Component ReliabilityEngineer, Intel Corp., Santa Clara, California, USA