Lasers are quantum devices of emission and amplification of the radiation in the optical area and in microwaves one, which bases its functionality on the interaction of two physical systems: the electromagnetic field in a resonant cavity and the active field, located in the same cavity resonance, made up of atoms, ions, molecules etc.
Laser performance increases in a significant way if it is inside of an optical resonator.
The first optical laser, built in 1960, was a laser with pulse, due to heat dissipation and the need for large pumping energy. The first laser created was the continuous one, the ruby laser and it functions on the principle of replacing the source (a lamp-flash) with an arc lamp.
Shortly after it was announced the first successful optical laser, other research laboratories have started successfully, to experiment with optical lasers.
Ruby laser
Ruby laser consists mainly of a cylindrical ruby crystal, two parallel mirrors, silver or gold and a discharge tube, spiral-shaped, filled with a noble gas and connected to a high capacity condenser. The two plane and parallel mirrors, polished with great care, are silver or gold so that one of them is completely opaque and the other partially transparent, in order to allow laser light to leave the facility.
They are placed in ruby cylinder heads. The discharge tube, spiral-shaped, filled with neon, xenon or mixtures of neon and krypton is connected to a condenser and works like flashes from the photo cameras. The discharge tube emits a very short time, the order of milliseconds, an ordinary light, but intense, which causes the inversion of the population in the ruby crystal.
Liquid lasers
The most famous liquid lasers are those with the organic components and the ones that contain dyes.
The active medium for the second ones consists of a fluorescent substance dissolved in a solvent (alcohol). Spectral width of radiation emitted is several hundred angstroms and can be selected the desired wavelength, so the laser it becomes provided in a broadband.
Ray laser
The plasma cylinder (red colored) is created by the impact of a high power laser pulse which is blue colored. In this process there are no mirrors used, but in turn the spontaneous emission are amplified and the beam is sent in both directions.
When the use of lasers is brought into discussion there are strong reasons to pay attention to this area, especially when it is associated with the engineering area. Regarding this association, the most known areas where the lasers are applied are represented by holography and holographic, optical communications, computer and integrated optics, the production and the plasma diagnostics, telemetry and speed measurement, automatic control of the machines, heating without a phase change for the materials, the melting and welding of metals, the vaporization and the deposition of thin layers, making an ultra-fast photo and the manufacture and the testing of electronic components;
Also, lasers are part of the current optical revolution. This involves the replacement of the electronic devices with photonic devices. Photonic device uses photons instead of electrons and the lasers are an excellent source for many applications. Although the main currently photonic devices, in use, are networks of long distance optical fiber, many scientists predict the imminent appearance of photonic the photonic computers.
