Hanushek / Jackson / Rossi Statistical Methods for Social Scientists

1. Auflage 2013
ISBN: 978-0-08-091857-0
Verlag: Elsevier Science & Techn.
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 374 Seiten, Web PDF

The aspects of this text which we believe are novel, at least in degree, include: an effort to motivate different sections with practical examples and an empirical orientation; an effort to intersperse several easily motivated examples throughout the book and to maintain some continuity in these examples; and the extensive use of Monte Carlo simulations to demonstrate particular aspects of the problems and estimators being considered. In terms of material being presented, the unique aspects include the first chapter which attempts to address the use of empirical methods in the social sciences, the seventh chapter which considers models with discrete dependent variables and unobserved variables. Clearly these last two topics in particular are quite advanced--more advanced than material that is currently available on the subject. These last two topics are also currently experiencing rapid development and are not adequately described in most other texts.

Eric Hanushek is the Paul and Jean Hanna Senior Fellow at the Hoover Institution of Stanford University. He is internationally recognized for his economic analysis of educational issues, and his research has had broad influence on education policy in both developed and developing countries. He received the Yidan Prize for Education Research in 2021. He is the author of numerous widely-cited studies on the effects of class size reduction, school accountability, teacher effectiveness, and other topics. He was the first to research teacher effectiveness by measuring students' learning gains, which forms the conceptual basis for using value-added measures to evaluate teachers and schools, now a widely adopted practice. His recent book with Ludger Woessmann, The Knowledge Capital of Nations: Education and the Economics of Growth summarizes research establishing the close links between countries' long-term rates of economic growth and the skill levels of their populations. He has authored or edited twenty-five books along with over 300 articles. He is a Distinguished Graduate of the United States Air Force Academy and completed his Ph.D. in economics at the Massachusetts Institute of Technology. [e-mail]; http://hanushek.stanford.edu/

Autoren/Hrsg.

Hanushek, Eric A.

Jackson, John E.

Rossi, Peter H.

Inhaltsverzeichnis

1;Front Cover;1
2;Semiconductor Lasers I;4
3;Copyright Page;5
4;Contents;6
5;Preface;10
6;Chapter 1. Quantum Well Semiconductor Lasers;14
6.1;1.1 Introduction;14
6.2;1.2 Carriers and photons in semiconductor structures;21
6.3;1.3 Basics of quantum well lasers;34
6.4;1.4 State filling in quantum well lasers;57
6.5;1.5 Reduction of state filling in QW lasers;80
6.6;1.6 Some performance characteristics of QW lasers;97
6.7;1.7 Conclusion and outlook;121
6.8;References;122
7;Chapter 2. Strained Quantum Well Lasers;136
7.1;2.1 Introduction;136
7.2;2.2 Strained layer structures;140
7.3;2.3 Electronic structure and gain;144
7.4;2.4 Visible lasers;160
7.5;2.5 Long-wavelength lasers;165
7.6;2.6 Linewidth, chirp, and high-speed modulation;180
7.7;2.7 Strained laser amplifiers;182
7.8;2.8 Conclusions;183
7.9;Acknowledgments;184
7.10;References;184
8;Chapter 3. High-Speed Lasers;190
8.1;3.1 Introduction;190
8.2;3.2 Laser dynamics;192
8.3;3.3 High-speed laser design;215
8.4;3.4 Large-signal modulation;275
8.5;3.5 Conclusions and outlook;291
8.6;Acknowledgments;293
8.7;References;293
9;Chapter 4. Quantum Wire and Quantum Dot Lasers;304
9.1;4.1 Introduction;304
9.2;4.2 Principles of QWR and QD lasers;307
9.3;4.3 Quantum wire lasers;320
9.4;4.4 Quantum dot lasers;352
9.5;4.5 Conclusions and outlook;365
9.6;Acknowledgments;366
9.7;References;366
10;Chapter 5. Quantum Optics Effects in Semiconductor Lasers;374
10.1;5.1 Introduction;374
10.2;5.2 Squeezing in semiconductor lasers;375
10.3;5.3 Controlled spontaneous emission in semiconductor lasers;427
10.4;5.4 Conclusion;450
10.5;References;450
11;Index;456

Leseproben

Chapter 1 Quantum Well Semiconductor Lasers
Bin Zhao    Rockwell Semiconductor Systems, Newport Beach, CA Amnon Yariv    California Institute of Technology, Pasadena, CA 1.1 Introduction
Semiconductor lasers have assumed an important technological role since their invention in the early 1960s (Basov et al., 1961; Bernard and Duraffourg, 1961; Hall et al., 1962; Nathan et al., 1962). Judged by economic impact, semiconductor lasers have become the most important class of lasers. They are now used in applications such as cable TV signal transmission, telephone and image transmission, computer interconnects and networks, compact disc (CD) players, bar-code readers, laser printers, and many military applications. They are now figuring in new applications ranging from two-dimensional display panels to erasable optical data and image storage. They are also invading new domains such as medical, welding, and spectroscopic applications that are now the captives of solid-state and dye lasers. The main reasons behind this major surge in the role played by semiconductor lasers are their continued performance improvements especially in low-threshold current, high-speed direct current modulation, ultrashort optical pulse generation, narrow spectral linewidth, broad line-width range, high optical output power, low cost, low electrical power consumption and high wall plug efficiency. Many of these achievements were based on joint progress in material growth technologies and theoretical understanding of a new generation of semiconductor lasers — the quantum well (QW) lasers. The pioneering work using molecular beam epitaxy (MBE) (Cho, 1971; Cho et al., 1976; Tsang, 1978; Tsang et al., 1979) and metal organic chemical vapor deposition (MOCVD) (Dupuis and Dapkus, 1977; Dupuis et al., 1978, 1979a, 1979b) to grow ultrathin semiconductor layers, on the order of ten atomic layers, had paved the way for the development of this new type of semiconductor laser. The early theoretical understanding and experimental investigations in the properties of QW lasers had helped speed up the development work (van der Ziel et al., 1975; Holonyak et al., 1980; Dutta, 1982; Burt, 1983; Asada et al., 1984; Arakawa et al., 1984; Arakawa and Yariv, 1985.) As shown in Fig. 1.1, a semiconductor laser is basically a p-i-n diode. When it is forward-biased, electrons in the conduction band and holes in the valence band are injected into the intrinsic region (also called the active region) from the n-type doped and the p-type doped regions, respectively. The electrons and the holes accumulate in the active region and are induced to recombine by the lasing optical field present in the same region. The energy released by this process (a photon for each electron-hole recombination) is added coherently to the optical field (laser action). In conventional bulk semiconductor lasers, as shown in Fig. 1.1, a double heterostructure (DH) is usually used to confine the injected carriers and the optical field to the same spatial region, thus enhancing the interaction of the charge carriers with the optical field. Figure 1.1 A schematic description of a semiconductor laser diode: (a) the laser device geometry; (b) the energy band structure of a forward-biased double heterostructure laser diode; (c) the spatial profile of the refractive index that is responsible for the dielectric waveguiding of the optical field; (d) the intensity profile of the fundamental optical mode. In order for optical radiation at frequency v to experience gain (amplification) rather than loss in a semiconductor medium, the separation between the Fermi energies of electrons and holes in the medium must exceed the photon energy hv (Basov et al., 1961 Bernard and Duraffourg, 1961). To achieve this state of affairs for lasing, a certain minimum value of injected carrier density Ntr (transparency carrier density) is required. This transparency carrier density is maintained by a (transparency) current in a semiconductor laser, which is usually the major component of the threshold current and can be written as tr-JtrwL   (1.1) where w is the laser diode width and L is the laser cavity length. Jtr is the transparency current density, which can be written as tr=eNtrdtc   (1.2) where e is the fundamental electron charge, d is the active layer thickness, and tc is the carrier lifetime related to spontaneous electron-hole recombination and other carrier loss mechanism at injection carrier density Ntr. Equations (1.1) and (1.2) suggest the strategies to minimize the threshold current of a semiconductor laser: (1) to reduce the dimensions of the laser active region (w, L, d), (2) to reduce the necessary inversion carrier density Ntr for the required Fermi energy separation, and (3) to reduce the carriers' spontaneous recombination and other loss mechanism (increase tc). Each of these strategies has stimulated exciting research activities in semiconductor lasers. For example, pursuing strategy (1) has resulted in the generation of quantum well, quantum wire, quantum dot, and micro cavity semiconductor lasers. Pursuing strategy (2) has resulted in the electronic band engineering for semiconductor lasers, such as the reduction in valence band effective mass and increase in subband separation caused by addition of strain to the QW region. Pursuing strategy (3) has led to the development of various fantastic semiconductor laser structures and materials to reduce leakage current and to suppress the Auger recombination. It also has stimulated the interesting research in squeezing the spontaneous emission in micro cavity for thresholdless semiconductor lasers (see Chap. 5). In addition to threshold current, other important performance characteristics of semiconductor lasers have been improved by these and other related research and development activities, which include the modulation speed, optical output power, laser reliability, etc. Figure 1.2 shows the schematic structures for three-dimensional (3D) bulk, two-dimensional (2D) quantum well, one-dimensional (1D) quantum wire, and zero-dimensional (0D) quantum dot and their corresponding carrier density of states (DOS). The electronic and optical properties of a semiconductor structure are strongly dependent on its DOS for the carriers. The use of these different structures as active regions in semiconductor lasers results in different performance characteristics because of the differences in their DOS as shown in Figure 1.2. Figure 1.2 Schematic structures and corresponding carrier density of states (DOS) for three-dimensional (3D) bulk, two-dimensional (2D) quantum well, one-dimensional (1D) quantum wire, and zero-dimensional (0D) quantum dot semiconductor lasers. Equation (1.2) shows that a reduction in the active layer thickness d will lead to a reduction in the transparency current density, which is usually the major component of the threshold current density. As the active layer thickness d is reduced from ~ 1000 Å in conventional DH lasers by an order of magnitude to ~ 100 Å, the threshold current density, and hence the threshold current, should be reduced by roughly the same order of magnitude. However, as d approaches the 100-Å region, the DH structure shown in Fig. 1.3(a) cannot confine the optical field any more. To effectively confine a photon or an electron, the feature size of the confinement structure needs to be comparable with their wavelengths. Thus a separate confinement heterostructure (SCH) as shown in Fig. 1.3(b) is needed. In an SCH structure, the injected carriers are confined in the active region of quantum size, a size comparable to the material wavelength of electrons and holes, in the direction perpendicular to the active layer, while the optical field is confined in a region with size comparable with its wavelength. The active layer is a so-called quantum well, and the lasers are called quantum well (QW) lasers. The electrons and the holes in the quantum well display quantum effects evidenced mostly by the modification in the carrier DOS. The quantum effects greatly influence the laser performance features such as radiation polarization, modulation, spectral purity, ultrashort optical pulse generation, as well as lasing wavelength tuning and switching. Figure 1.3 Schematic structures for (a) bulk double heterostructure (DH) semiconductor lasers; (b) separate confinement heterostructure (SCH) quantum well (QW) semiconductor lasers. This chapter is devoted mainly to a general description of QW lasers. Extensive discussions on QW lasers were given by many experts in a book edited by Zory (1993). Various discussions on this subject also can be found in other books (e.g., Weisbuch and Vinter, 1991; Agrawal and Dutta, 1993; Chow et al.,...