Book contents
- Frontmatter
- Contents
- Preface
- 1 Scalar wave equations and diffraction of laser radiation
- 2 Gaussian modes in optical laser cavities and Gaussian beam optics
- 3 Guided wave modes and their propagation
- 4 Guided wave interactions and photonic devices
- 5 Macroscopic properties of materials from stimulated emission and absorption
- 6 Solid state and gas laser amplifier and oscillator
- 7 Semiconductor lasers
- Index
- References
7 - Semiconductor lasers
Published online by Cambridge University Press: 06 July 2010
- Frontmatter
- Contents
- Preface
- 1 Scalar wave equations and diffraction of laser radiation
- 2 Gaussian modes in optical laser cavities and Gaussian beam optics
- 3 Guided wave modes and their propagation
- 4 Guided wave interactions and photonic devices
- 5 Macroscopic properties of materials from stimulated emission and absorption
- 6 Solid state and gas laser amplifier and oscillator
- 7 Semiconductor lasers
- Index
- References
Summary
The general principles of amplification and oscillation in semiconductor lasers are the same as those in solid state and gas lasers, as discussed in Chapter 6. A negative χ″ is obtained in an active region via induced transitions of the electrons. When the gain per unit distance is larger than the propagation loss, laser amplification is obtained. In order to achieve laser oscillation, the active material is enclosed in a cavity. Laser oscillation begins when the gain exceeds the losses, including the output. However, the details are quite different. In this chapter, the discussion on semiconductor lasers will use much of the analyses already developed in Chapters 5 and 6; however, the differences will be emphasized.
In semiconductor lasers, free electrons and holes are the particles that undertake stimulated emission and absorption. How such free carriers are generated, transported and recombined has been discussed extensively in the literature. We note here, in particular, that free electrons and holes are in a periodic crystalline material. The energy levels of electrons and holes in such a material are distributed within conduction and valence bands. The distribution of energy states within each band depends on the specific semiconductor material and its confinement within a given structure. For example, it is different for a bulk material (a three-dimensional periodic structure) and for a quantum well (a two-dimensional periodic structure).
- Type
- Chapter
- Information
- Principles of Lasers and Optics , pp. 212 - 244Publisher: Cambridge University PressPrint publication year: 2005