Laser technology is one of the most rapidly developing areas in modern technology.
When the laser was invented, in 1960, it was classified as a solution in search of a problem, and today laser technology is applied in many different areas such as: medicine, communication, daily use, military, and industry.
To explain how the laser can be applied in such diverse areas, we need to understand the basic physical principles of the operation of a laser.
In principle, the laser is a device which transforms energy from other forms into electromagnetic radiation. This is a very general definition, but it helps to understand the basic physics of the laser.
The energy put into the laser can be in any form such as:
Energy is always emitted from the laser as electromagnetic radiation (which includes light beams).
From this light output, the laser got part of its name:
LASER = Light Amplification by Stimulated Emission of Radiation.
The terms used in this definition will be explained later in this course(1).
As we see, the word laser started as an acronym, but it is now accepted as a word, with other words derived from it: "to lase", "lasing" etc.
will try to obtain a qualitative
picture of the quantum nature of the laser,
based on some basic principles which came from the advanced mathematical