Long Wavelength Infrared Semiconductor Lasers

Long-wavelength Infrared Semiconductor Lasers provides a comprehensive review of the current status of semiconductor coherent sources emitting in the mid-to far-infrared spectrum and their applications. It includes three topics not covered in any previous book: far-infrared emission from photo-mixers as well as from hot-hole lasers, and InP-based lasers emitting beyond two micrometers. Semiconductor lasers emitting at more than two micrometers have many applications such as in trace gas analysis, environmental monitoring, and industrial process control. Because of very rapid progress in recent years, until this book no comprehensive information beyond scattered journal articles is available at present.

Since its invention in 1962, the semiconductor laser has come a long way. Advances in material purity and epitaxial growth techniques have led to a variety of semiconductor lasers covering a wide wavelength range of 0. 3- 100 ILm. The development during the 1970s of GaAs semiconductor lasers, emitting in the near-infrared region of 0. 8--0. 9 ILm, resulted in their use for the first generation of optical fiber communication systems. However, to take advantage of low losses in silica fibers occurring around 1. 3 and 1. 55 ILm, the emphasis soon shifted toward long-wavelength semiconductor lasers. The material system of choice in this wavelength range has been the quaternary alloy InGaAsP. During the last five years or so, the intense development effort devoted to InGaAsP lasers has resulted in a technology mature enough that lightwave transmission systems using InGaAsP lasers are currently being deployed throughout the world. This book is intended to provide a comprehensive account of long-wave length semiconductor lasers. Particular attention is paid to InGaAsP lasers, although we also consider semiconductor lasers operating at longer wave lengths. The objective is to provide an up-to-date understanding of semicon ductor lasers while incorporating recent research results that are not yet available in the book form. Although InGaAsP lasers are often used as an example, the basic concepts discussed in this text apply to all semiconductor lasers, irrespective of their wavelengths.

Since its invention in 1962, the semiconductor laser has come a long way. Advances in material purity and epitaxial growth techniques have led to a variety of semiconductor lasers covering a wide wavelength range of 0. 3- 100 ILm. The development during the 1970s of GaAs semiconductor lasers, emitting in the near-infrared region of 0. 8--0. 9 ILm, resulted in their use for the first generation of optical fiber communication systems. However, to take advantage of low losses in silica fibers occurring around 1. 3 and 1. 55 ILm, the emphasis soon shifted toward long-wavelength semiconductor lasers. The material system of choice in this wavelength range has been the quaternary alloy InGaAsP. During the last five years or so, the intense development effort devoted to InGaAsP lasers has resulted in a technology mature enough that lightwave transmission systems using InGaAsP lasers are currently being deployed throughout the world. This book is intended to provide a comprehensive account of long-wave length semiconductor lasers. Particular attention is paid to InGaAsP lasers, although we also consider semiconductor lasers operating at longer wave lengths. The objective is to provide an up-to-date understanding of semicon ductor lasers while incorporating recent research results that are not yet available in the book form. Although InGaAsP lasers are often used as an example, the basic concepts discussed in this text apply to all semiconductor lasers, irrespective of their wavelengths.

This book offers a thorough survey of long wavelength infrared semiconductor emitters based primarily on quantum wells and superlattices. Featuring contributions from the most prominent researchers in the field, this volume allows readers to compare different types of lasers as well as examine investigations of potential far-infrared/terrahertz sources. This is an essential reference for researchers, engineers and graduate students who wish to obtain comprehensive knowledge about infrared semiconductor sources and recent developments in this field.

Since its invention in 1962, the semiconductor laser has come a long way. Advances in material purity and epitaxial growth techniques have led to a variety of semiconductor lasers covering a wide wavelength range of 0. 3- 100 ~m. The development during the 1970s of GaAs semiconductor lasers, emitting in the near-infrared region of 0. 8-0. 9 ~m, resulted in their use for the first generation of optical fiber communication systems. However, to take advantage oflow losses in silica fibers occurring around 1. 3 and 1. 55 ~m, the emphasis soon shifted toward long-wavelength semiconductor lasers. The material system of choice in this wavelength range has been the quaternary alloy InGaAsP. During the last five years or so, the intense development effort devoted to InGaAsP lasers has resulted in a technology mature enough that lightwave transmission systems using InGaAsP lasers are currently being deployed throughout the world. This book is intended to provide a comprehensive account of long-wave length semiconductor lasers. Particular attention is paid to InGaAsP lasers, although we also consider semiconductor lasers operating at longer wave lengths. The objective is to provide an up-to-date understanding of semicon ductor lasers while incorporating recent research results that are not yet available in the book form. Although InGaAsP lasers are often used as an example, the basic concepts discussed in this text apply to all semiconductor lasers, irrespective of their wavelengths.

Quantum cascade lasers (QCLs) are semiconductor lasers that emit in the mid- to far-infrared and employ intersubband transitions in multiple quantum-well structures. Conventionally, the active region of QCLs has consisted of quantum wells and barriers of fixed-alloy composition. That has led to severe carrier leakage from the upper-laser level and injector states, evidenced by strong temperature dependences of the device characteristics, which resulted in low values for wall-plug efficiency [eta]wp of CW-operating devices. We have devised in the past means for carrier-leakage suppression, and have recently derived a comprehensive carrier-leakage formalism that bridges the gap between theoretical and experimental values for the internal efficiency. Here we present a refinement of the comprehensive carrier-leakage formalism and employ it for comparing our band-engineered ~ 8 [mu]m-emitting QCL, so-called step-tapered active-region (STA), to a conventional ~ 8 [mu]m-emitting QCL. We find that the internal efficiency reaches a high value of ~ 73.6%, due to record-high injection- and laser-transition efficiencies. Experimentally we obtain a single-facet [eta]wp value of 10.6%, a record-high value for 8-11 Îơm-emitting QCLs grown by MOCVD. Then, by using both band- and interface-roughness (IFR)-scattering - engineering we designed an optimized 8.2 [mu]m-emitting STA-QCL that reaches a record-high injection efficiency of 89.5%. By minimizing the waveguide loss and raising the doping level the device reaches a record-high internal efficiency (80%) for ~ 8 [mu]m-emitting QCLs as well as a projected [eta]wp value of 11.2%. The studies are extended to devices of higher layer-interface quality, grown by two different techniques. As a result, we obtain [eta]wp values as high as 15.6 %. In addition, the optimized STA-QCL has a lower-level lifetime dominated by IFR scattering, which makes it amenable to further optimization via IFR engineering. Finally, we analyze an ~ 8 [mu]m-emitting QCLs that holds the world record [eta]wp value, primarily due to low voltages via the realization of photon-induced carrier transport. We find that the device has significant carrier leakage, and show that our optimized STA QCL can reach comparable [eta]wp values if high-quality interfaces are employed. We then derive ultimate limits for the [eta]wp value in the 7-11 [mu]m wavelength range.

Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series.