Types of Lasers

Types of Lasers

There are several different types of lasers. The differences depend on the type of active medium used. The active medium can be:
A. Gas
B. Solid
C. Semiconductor
D. Dye

A. Gas Lasers
Gas lasers use gas as the active medium. Excitation is achieved by a current flowing through a gas filled tube. These lasers can be continuous wave or pulsed. Examples of gas lasers are HeNe, Argon, and C02. These lasers can be used for welding and cutting, eye surgery and entertainment.

B. Solid Lasers
Solid lasers use a solid crystal or glass as the active medium. The excitation energy comes from pumping a flashlamp or light. Examples of solid lasers are Ruby and Neodymium: YAG. Solid lasers are used for measuring, eye surgery, and hole drilling.

C. Semiconductor Lasers
Semiconductor lasers use a junction between two types of semiconductor materials. A semiconductor is a material whose conductivity is greater than that of an insulator but less than a good conductor such as copper. The excitation mechanism is a current that flows between two semiconductors that have been joined together. An example of a semiconductor laser is GaAs- Gallium Arsenide. A distinguishing characteristic of semiconductor lasers is their extremely small size. They are about the size of a grain of sand. These lasers are used in precision measuring and communications.

D. Dye Lasers
Organic dye lasers use dyes dissolved in alcohol as the active medium. Some use rhodamin 6G and some use disodium fluorescein. The dye solution is circulated by a pump through a glass or quartz tube. The excitation mechanism is a pulse of light from a flashlamp or another laser. A distinguishing feature of dye lasers is that they can be 'Tuned" to a particular wavelength by changing the concentration of the dye solution so a larger range of wavelengths can be obtained. These lasers are used in spectroscopy and special photography.

from J. King