Rami Arieli: "The Laser Adventure" Chapter 6 Page 1.
Chapter 6: Different Laser Types and their Characteristics

Chapters 1-5 laid the theoretical background which explains the Lasing Process, and the main parts of the laser.
This chapter explains the different types of lasers.

 Lasers can be divided into groups according to different criteria:

  1. The state of matter of the active medium: solid, liquid, gas, or plasma.
  2. The spectral range of the laser wavelength: visible spectrum, Infra-Red (IR) spectrum, etc.
  3. The excitation (pumping) method of the active medium: Optic pumping, Electric pumping, etc.
  4. The characteristics of the radiation emitted from the laser.
  5. The number of energy levels which participate in the lasing process.