Lasers and Optoelectronics

Dr. Anil Kumar Maini, Director, Laser Science & Technology Centre (DRDO) Metcalfe House, LASTEC, Delhi 110054 (INDIA)E-mail: maini_anil1@rediffmail.com Dr. Anil K. Maini is presently Director of Laser science and technology centre, Delhi, a premier R&D Laser Laboratory of Defence Research and Development Organization under Ministry of Defence, Govt. of India. He has more than 35 years of R&D experience as a Scientist, Team Leader, Project Director and Director in diverse disciplines related to Electronics, Lasers and Optoelectronics technologies and systems. His contributions have led to number of innovations in the development of different types of Electronics systems, Optronic sensors and Directed energy laser systems for Indian Defence forces. The key products and technologies developed under his guidance include Power Electronics Systems, family of Laser Dazzling Systems for Homeland security applications, Laser Systems for Electro Optic Counter Measures (EOCM) applications and Optoelectronic Simulators & Sensors for electro optically guided precision strike munitions.Dr. Anil K. Maini is Life Fellow of Institution of Electronics and Telecommunication Engineers (IETE) and a senior life member of Indian Laser Association. He has written extensively on a wide range of subjects in Electronics and Optoelectronics. He has authored and co-authored twelve books, 6 of the twelve books being international publications. He has delivered numerous invited talks at various universities and research centres. He has worked with several international universities under different collaborative research programmes. He has to his credit five patents and more than 125 publications in National and International journals.

• Preface xix Part I LASER FUNDAMENTALS 11 Laser Basics 31.1 Introduction 31.2 Laser Operation 31.3 Rules of Quantum Mechanics 31.4 Absorption, Spontaneous Emission and Stimulated Emission 41.5 Population Inversion 101.6 Two-, Three- and Four-Level Laser Systems 111.7 Gain of Laser Medium 161.8 Laser Resonator 171.9 Longitudinal and Transverse Modes 181.10 Types of Laser Resonators 211.11 Pumping Mechanisms 231.12 Summary 292 Laser Characteristics 342.1 Introduction 342.2 Laser Characteristics 342.3 Important Laser Parameters 412.4 Measurement of Laser Parameters 492.5 Laser Beam Diagnostic Equipment 562.6 Summary 59Part II TYPES OF LASERS 653 Solid-state Lasers 673.1 Introduction: Types of Laser 673.2 Importance of Host Material 673.3 Operational Modes 683.4 Ruby Lasers 763.5 Neodymium-doped Lasers 783.6 Erbium-doped Lasers 853.7 Vibronic Lasers 883.8 Colour Centre Lasers 903.9 Fibre Lasers 913.10 Summary 1014 Gas Lasers 1054.1 Introduction to Gas Lasers 1054.2 Helium-neon Lasers 1074.3 Carbon Dioxide Lasers 1114.4 Metal Vapour Lasers 1154.5 Rare Gas Ion Lasers 1184.6 Excimer Lasers 1204.7 Chemical Lasers 1214.8 Carbon Dioxide Gas Dynamic Lasers 1254.9 Dye Laser 1254.10 Free-electron Lasers 1274.11 X-Ray Lasers 1294.12 Summary 1295 Semiconductor Lasers 1325.1 Introduction 1325.2 Operational Basics 1325.3 Semiconductor Laser Materials 1355.4 Types of Semiconductor Lasers 1365.5 Characteristic Parameters 1485.6 Gain- and Index-guided Diode Lasers 1525.7 Handling Semiconductor Diode Lasers 1525.8 Semiconductor Diode Lasers: Application Areas 1535.9 Summary 154Part III LASER ELECTRONICS AND OPTOELECTRONICS 1596 Building Blocks of Laser Electronics 1616.1 Introduction 1616.2 Linear Power Supplies 1616.3 Switched-mode Power Supplies 1736.4 Constant Current Sources 1866.5 Integrated-circuit Timer Circuits 1916.6 Current-to-voltage Converter 1976.7 Peak Detector 1996.8 High-voltage Trigger Circuit 2006.9 Summary 2027 Solid-state Laser Electronics 2087.1 Introduction 2087.2 Spectrum of Laser Electronics 2087.3 Electronics for Solid-state Lasers 2137.4 Electronics for Pulsed Solid-state Lasers 2147.5 Electronics for CW Solid-state Lasers 2337.6 Solid-state Laser Designators and Rangefinders 2377.7 Summary 2388 Gas Laser Electronics 2428.1 Introduction 2428.2 Gas Discharge Characteristics 2428.3 Gas Laser Power Supplies 2428.4 Helium-Neon Laser Power Supply 2448.5 Carbon Dioxide Laser Power Supplies 2578.6 Power Supplies for Metal Vapour Lasers 2608.7 Power Supplies for Excimer Lasers 2618.8 Power Supplies for Ion Lasers 2628.9 Frequency Stabilization of Gas Lasers 2638.10 Summary 2679 Laser Diode Electronics 2719.1 Introduction 2719.2 Laser Diode Protection 2719.3 Operational Modes 2769.4 Laser Diode Driver Circuits 2789.5 Laser Diode Temperature Control 2919.6 Summary 30810 Optoelectronic Devices and Circuits 31510.1 Introduction 31510.2 Classification of Photosensors 31510.3 Radiometry and Photometry 31610.4 Characteristic Parameters 31810.5 Photoconductors 32410.6 Photodiodes 32910.7 Phototransistors 34010.8 Photo- FET, SCR and TRIAC 34310.9 Photoemissive Sensors 34510.10 Thermal Sensors 34710.11 Displays 34910.12 Light-emitting Diodes 35110.13 Liquid-crystal Displays 35610.14 Cathode Ray Tube Displays 36110.15 Emerging Display Technologies 36210.16 Optocouplers 36310.17 Summary 370Part IV LASER APPLICATIONS 37911 Lasers in Industry 38111.1 Introduction 38111.2 Material-processing Applications 38111.3 Laser Cutting 38511.4 Laser Welding 39011.5 Laser Drilling 39311.6 Laser Marking and Engraving 39611.7 Laser Micromachining 40111.8 Photolithography 40711.9 Rapid Manufacturing 41111.10 Lasers in Printing 41411.11 Summary 41812 Lasers in Medicine 42212.1 Introduction 42212.2 Light–tissue Interaction 42212.3 Laser Diagnostics 43012.4 Therapeutic Techniques: Application Areas 44212.5 Ophthalmology 44312.6 Dermatology 44912.7 Laser Dentistry 45312.8 Vascular Surgery 45512.9 Photodynamic Therapy 45612.10 Thermal Therapy 45912.11 Summary 46013 Lasers in Science and Technology 46613.1 Introduction 46613.2 Optical Metrology 46613.3 Laser Velocimetry 47813.4 Laser Vibrometry 48213.5 Electronic Speckle Pattern Interferometry 48413.6 Satellite Laser Ranging 49013.7 Lasers in Astronomy 49413.8 Holography 49613.9 Summary 50314 Military Applications: Laser Instrumentation 50814.1 Introduction 50814.2 Military Applications of Lasers 50814.3 Laser-based Instrumentation 51214.4 Guided Munitions 53214.5 Laser Communication 55614.6 Summary 56115 Military Applications: Directed-energy Laser Systems 56615.1 Introduction 56615.2 Laser Technology for Low-intensity Conflict (LIC) Applications 56615.3 Electro-optic Countermeasures 58015.4 Directed-energy Laser Weapons 58515.5 Summary 592Review Questions 595Self-evaluation Exercise 596Bibliography 598Appendix A: Laser Safety 597Index 603