Lasers can be used in many applications, from industrial cutting to business presentations. Their name is actually an acronym for Light Amplification by Stimulated Emission of Radiation. As most people can probably tell, lasers are much more intense than the average light, because, in essence, they are much more concentrated.

Operation Principle

Lasers function on the basic operating principle of causing multiple photons to all go the same direction and all have the same frequency all at the same time. Because photons are moving at the speed of light, this is somewhat difficult. However, it can be achieved by a multitude of methods. These methods mostly share the commonality that they use a gain medium, which is the part of the laser that contains the atoms that are excited in order that they can be in a position to emit photons of light. Most lasers also have two mirrors, one on each side of the gain medium. One of these mirrors is semi-transparent and is the one through which photons pass out of the laser. The other mirror is completely reflective, and serves to keep the photons of light in the gain medium until enough photons are traveling in the same direction and in the right color that they can be emitted. The exception to this operation principle is the laser diode, which uses electronics to produce a laser.

Gas Lasers

Gas lasers are simply lasers that use pressurized gases as a gain medium. This gain medium must be electrically charged in order to induce a state known as population inversion. In this state, more atoms of whatever gas is being used become excited (meaning they have the potential to emit a photon of light) than are not excited in the entire population of atoms. Once the gain medium reaches population inversion, the excited atoms start releasing photons of light. These photons can only pass through the front of the laser when they reach a certain frequency. When they do, they pass through the front of the laser along with many other photons of the same frequency. This causes the emission of the laser, which is then amplified by a lens.

Laser Diodes

Laser diodes are much smaller than gas lasers, which accounts for their usage in smaller devices such as laser pens. These diodes have two primary substances in them. One substance contains electrons, and the other contains electron holes, which are the physical opposite of an electron. When the electrons are electrified, they jump down in energy and fill the electron holes in the other substance. This releases photons of all the same frequency and all the same direction, hence emitting a laser beam.

Solid State Lasers

A solid state laser is very similar to a gas laser. The primary difference is that a solid state laser uses a solid as its gain medium. This solid is usually a crystalline substance.

Uses of Lasers

Gas lasers are generally used for industrial purposes such as cutting and engraving. For these purposes, CO2 lasers are commonly used. Laser diodes are used in smaller devices, such as laser pens and CD/DVD drives. Solid state lasers are not used very often, but currently, they are being developed in the field of military weapons technology.