Diode Lasers

Diode Lasers and Photonic Integrated Circuits, Second Edition provides a comprehensive treatment of optical communication technology, its principles and theory, treating students as well as experienced engineers to an in-depth exploration of this field. Diode lasers are still of significant importance in the areas of optical communication, storage, and sensing. Using the the same well received theoretical foundations of the first edition, the Second Edition now introduces timely updates in the technology and in focus of the book. After 15 years of development in the field, this book will offer brand new and updated material on GaN-based and quantum-dot lasers, photonic IC technology, detectors, modulators and SOAs, DVDs and storage, eye diagrams and BER concepts, and DFB lasers. Appendices will also be expanded to include quantum-dot issues and more on the relation between spontaneous emission and gain.

Starting from the basics of semiconductor lasers with emphasis on the generation of high optical output power the reader is introduced in a tutorial way to all key technologies required to fabricate high-power diode-laser sources. Various applications are exemplified.

The compact size, reliability, and low cost of diode lasers lead to applications throughout modern technology-most importantly in modern optical telecommunication systems. This book presents a comprehensive introduction to the principles and operation of diode lasers. It begins with a review of semiconductor physics and laser fundamentals, before describing the most basic homojunction laser. Later chapters describe more advanced laser types and their applications, including the most recently developed and exotic laser designs. The author's intuitive style, coupled with an extensive set of worked examples and sample problems, make this an outstanding introduction to the subject.

This is the first book on tunable external cavity semiconductor diode lasers, providing an up-to-date survey on the physics, technology, and performance of widely applicable coherent radiation sources of tunable external cavity diode lasers. The purpose is to provide a thorough account of the state-of-the-art of tunable external cavity diode lasers which is achieved by combining this account with basic concepts of semiconductor diode lasers and its tunability with monolithic structures. The practical and accessible information in this volume will enable the reader to study external cavity diode laser, to build up the systems of external cavity diode laser as well as to develop advanced systems for their particular applications. This book will appeal to undergraduate and graduate students, scientists and engineers alike. Contents: Basics of Semiconductor Diode LasersTunable Monolithic Semiconductor Diode LasersElements of Tunable External Cavity Diode LasersSystems for Tunable External Cavity Diode LasersImplementation of Tunable External Cavity Diode LasersFrequency Stabilization of Tunable External Cavity Diode LasersApplications of Tunable External Cavity Diode Lasers Readership: Undergraduate & graduate students; researchers; scientists & engineers working in lasers, optics, optic networks and related areas. Keywords:Semiconductor Diode Laser;Tunable Diode Laser;Laser Diodes;Optoelectronic Devices;Principles of LasersKey Features:Presents a thorough account of the state-of-the-art of tunable external cavity diode lasersProvides an up-to-date survey on physics, technology, and performance of widely applicable coherent radiation sources of tunable external cavity diode lasersMay be used as a textbook for related undergraduate and graduate courses

A huge number of applications require coherent radiation in the visible spectral range. Since diode lasers are very compact and efficient light sources, there exists a great interest to cover these applications with diode laser emission. Despite modern band gap engineering not all wavelengths can be accessed with diode laser radiation. Especially in the visible spectral range between 480 nm and 630 nm no emission from diode lasers is available, yet. Nonlinear frequency conversion of near-infrared radiation is a common way to generate coherent emission in the visible spectral range. However, radiation with extraordinary spatial temporal and spectral quality is required to pump frequency conversion. Broad area (BA) diode lasers are reliable high power light sources in the near-infrared spectral range. They belong to the most efficient coherent light sources with electro-optical efficiencies of more than 70%. Standard BA lasers are not suitable as pump lasers for frequency conversion because of their poor beam quality and spectral properties. For this purpose, tapered lasers and diode lasers with Bragg gratings are utilized. However, these new diode laser structures demand for additional manufacturing and assembling steps that makes their processing challenging and expensive. An alternative to BA diode lasers is the stripe-array architecture. The emitting area of a stripe-array diode laser is comparable to a BA device and the manufacturing of these arrays requires only one additional process step. Such a stripe-array consists of several narrow striped emitters realized with close proximity. Due to the overlap of the fields of neighboring emitters or the presence of leaky waves, a strong coupling between the emitters exists. As a consequence, the emission of such an array is characterized by a so called supermode. However, for the free running stripe-array mode competition between several supermodes occurs because of the lack of wavelength stabilization. This leads to power fluctuations, spectral instabilities and poor beam quality. Thus, it was necessary to study the emission properties of those stripe-arrays to find new concepts to realize an external synchronization of the emitters. The aim was to achieve stable longitudinal and transversal single mode operation with high output powers giving a brightness sufficient for efficient nonlinear frequency conversion. For this purpose a comprehensive analysis of the stripe-array devices was done here. The physical effects that are the origin of the emission characteristics were investigated theoretically and experimentally. In this context numerical models could be verified and extended. A good agreement between simulation and experiment was observed. One way to stabilize a specific supermode of an array is to operate it in an external cavity. Based on mathematical simulations and experimental work, it was possible to design novel external cavities to select a specific supermode and stabilize all emitters of the array at the same wavelength. This resulted in stable emission with 1 W output power, a narrow bandwidth in the range of 2 MHz and a very good beam quality with M²<1.5. This is a new level of brightness and brilliance compared to other BA and stripe-array diode laser systems. The emission from this external cavity diode laser (ECDL) satisfied the requirements for nonlinear frequency conversion. Furthermore, a huge improvement to existing concepts was made. In the next step newly available periodically poled crystals were used for second harmonic generation (SHG) in single pass setups. With the stripe-array ECDL as pump source, more than 140 mW of coherent radiation at 488 nm could be generated with a very high opto-optical conversion efficiency. The generated blue light had very good transversal and longitudinal properties and could be used to generate biphotons by parametric down-conversion. This was feasible because of the improvement made with the infrared stripe-array diode lasers due to the development of new physical concepts.

This book summarizes a five year research project, as well as subsequent results regarding high power diode laser systems and their application in materials processing. The text explores the entire chain of technology, from the semiconductor technology, through cooling mounting and assembly, beam shaping and system technology, to applications in the processing of such materials as metals and polymers. Includes theoretical models, a range of important parameters and practical tips.

This book is the result of the authors' many years of experience in using neurosurgical lasers. They began using laser diodes in their speciality at the start of the 1990s, making them pioneers in the field. The first part of the book deals with the general physical bases and comparative bio-tissue effects of the various kinds of surgical laser, safety measures required and legislation concerning powerful lasers. The second part focuses on laser diodes alone. The authors describe in detail how they use them to operate on intracranial and intraspinal tumours, in intraventricular endoscopy, and in surgery involving epilepsy. Details are given of: technical data; the choice of parameters depending on how the lasers are used (contact and non-contact, and the type of lesion being operated on) as well as their indications in neurosurgery. The authors emphasise the practical recommendations that make this book a valuable companion for current and potential users working in neurosurgery and other surgical applications. They also mention the new and future uses of laser diodes which are currently being developed and which show that this equipment really does represent a new generation of lasers. About 100 colour illustrations and tables are used to explain and underscore the authors' points.