Lasers
CHAPTER 1: THE BASICS
Basic laser physics: Introduction; Absorption; Spontaneous and stimulated emission of light; Amplification; Basic laser setup; Gain, saturation and line broadening
Basic properties of laser light: One direction; One frequency; One phase; Laser light is intense
CHAPTER 2: LASER THEORY
Introduction: The need for more than two energy levels; Rate equations for a 4-level laser
Continuous-wave (cw) laser action: Output power in cw regime; Influence of experimental parameters; Transients
Pulsed laser action: Introduction; Gain switching; Q-switching; Cavity dumping; Mode-locking; Ultra-short pulses
CHAPTER 3: LASER RESONATORS AND THEIR MODES
Introduction
Modes in a confocal resonator: Wave fronts; Frequencies; Transverse light distribution
Modes in a non-confocal resonator: Stability criteria; Frequencies
Modes in a waveguide resonator: Modes in a fiber waveguide resonator; Modes in an on-chip waveguide resonator
Modes in a (free-space/waveguide) ring resonator
Modes in a real laser: Line broadening; Selection of modes
Saturation and hole-burning effects: Spatial hole burning; Spectral hole burning
CHAPTER 4: LASER BEAMS
Gaussian beams: Basic Formulas; Propagation; Transformation by a lens and focusing; Transmission through a circular aperture
Multimode beams: Introduction; Spot radius W for a multimode beam; Beam Propagation Factor M; A more theoretical approach; Practical use
CHAPTER 5: TYPES OF LASERS
General introduction
Gas lasers: General; Neutral gas (He-Ne); Ionized gas (argon ion); Molecules (CO2); Excimer lasers (ArF)
Liquid lasers (dye laser)
Solid-state lasers: General; Rare-earth-doped lasers (Nd:YAG and Er:fiber); Transition-metal-doped lasers (Ti: Sapphire); Changing the wavelength by optical nonlinear effects
Other lasing mechanisms: Raman lasing
CHAPTER 6: LASER DIODES:OPERATION PRINCIPLES
Geometry and important characteristics
Material aspects: heterostructures, gain and absorption, low dimensional materials,
Gain saturation
Fabry-Perot laser diodes: cavity resonance
Fabry-Perot laser diodes: rate equations and dynamic operation
Noise: power spectrum and phase noise, injection locking
CHAPTER 7: OVERVIEW OF SEMICONDUCTOR LASER TYPES
Distributed Feedback and Distributed Bragg Reflector laser diodes
Vertical Cavity Surface Emitting Laser diodes
Tunable laser diodes
Quantum cascade lasers
Laser diode packaging
This course is part of the European Master of Science in Photonics. Chapters 1 to 5 are taught by N. Vermeulen, both at VUB and UGent. Chapters 6-7 are taught by G. Verschaffelt at VUB and by G. Morthier at UGent.
ALGEMENE COMPETENTIES
CONTEXT AND GENERAL AIM:
Since their invention in 1960, lasers have become the most important light sources in optics and photonics, and are present everywhere in modern society nowadays. For example, worldwide telecommunication is based on the transmission of laser signals through optical fibers, and today’s manufacturing industry heavily relies on the use of high-irradiance laser beams. Other application domains include medicine, art restoration, remote sensing, biological spectroscopy, and many others. It is the general aim of this course that the students will become able to explain and analyse laser properties and laser-related concepts, that they learn to construct and analyse the mathematical description of important concepts, and that they are also able to apply the latter to practical examples on the use of lasers.
END COMPETENCES:
The targeted end competences can be categorized as follows:
The students are able to name, describe and explain laser properties and concepts, including:
spontaneous and stimulated emission, absorption, coherence, heterostructures for efficient light generation, light propagation in a resonator, continuous-wave and pulsed laser action, line broadening, saturation, Gaussian laser beams, operation and applications of different laser types (gas lasers, liquid lasers, solid-state lasers, semiconductor lasers), laser dynamics, noise, Bragg gratings, wavelength tuning, laser packaging.
The students have the ability to derive from first principles the mathematical description for laser-related concepts, including:
rate equations describing the general operation principle of laser action and formulas for continuous-wave/pulsed laser operation, formulas for the modes in different types of resonators with different stability criteria, equations for propagation and transformation of Gaussian and multimode laser beams in optical systems, laser rate equations for different types of semiconductor lasers, formulas describing the gain and complex refractive index in semiconductor materials, description of the linewidth of lasers, formulas for the dynamic behaviour of lasers.
The students know how to explain and analyse the above-enlisted mathematical descriptions for laser-related concepts.
The students are able to apply the mathematical descriptions to practical examples and to use these descriptions to solve practical problems.
EXAM:
The students are evaluated according to the above-enlisted end competences in an oral exam with written preparation (open questions, closed book).
Presential
FALSE
Lasers
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or HaDEA. Neither the European Union nor the granting authority can be held responsible for them. The statements made herein do not necessarily have the consent or agreement of the ASTRAIOS Consortium. These represent the opinion and findings of the author(s).
