There is many different laser technologies available on the market.
Lasers mainly differentiate from one another depending on their gain medium and architecture which affect their optical properties.
The laser effect can take place in different gain mediums like gas, crystals or glass, liquids, semi-conductors or optical fiber. Each gain medium have specific wavelength emission and absorption bands which will select the wavelength of the generated laser beam.
Furthermore, industrial lasers can be operated in continuous wave (CW) or pulsed regimen. Such regimen is chosen with regard to the application (marking, cutting, welding) and material type (metals, plastics, organic).
Fiber lasers are lasers in which the gain medium is an optical fiber doped with rare earth ions such as erbium (Er) or ytterbium (Yb). They are pumped by semiconductor laser diodes. The fiber laser cavity is built monolithically by fusion splicing different types of fibers and fiber Bragg gratings (which act as mirrors) to provide optical feedback directly within the fibers. Optical couplers are used to construct all integrated fiber lasers or amplifiers systems that enable to increase laser performances.
Commercially available lasers operating in continuous or modulated modes are ranging in average output power from 10 milliwatts to 50 kilowatts with wall-plug efficiencies greater than 30%!
Fiber lasers are essentially smaller in size and lighter in weight than traditional lasers, these features make fiber lasers easier to integrate in production lines. They also have a good output optical beam quality which is excellent for laser materials processing.
The most widespread fiber lasers are made of silica glass fibers and emit a wavelength of 1064 nm (Yb doped, material processing) and 1550 nm (Er doped, telecommunications). High power pulsed and CW fiber lasers at 1064 nm are used across the world for material processing of metals, including cutting thick metal sheets. The other main application of fiber lasers is for telecommunication.
While very efficient on metals, fiber lasers have low effect on most plastics and organic materials due to their lack of absorption at the current wavelengths light is emitted.
Excimer lasers are pulsed gas lasers that use a mixture of gas to generate laser emission. Excitation of the laser gas mixture is generally provided by a fast electrical discharge with a duration of a few tens of nanoseconds. The formation of short-lived excited molecule allows the laser action to take place as a result of the deexcitation of the species.
The wavelength emitted depends on the selection of rare gas and halogen gas mixture, the most commonly used mixture are argon fluoride (ArF) with an emission wavelength at 193 nm, krypton fluoride (KrF) at 248 nm, xenon monochloride (XeCl) at 308 nm and xenon fluoride (XeF) at 351 nm.
The benefits of these lasers are that UV light has good material absorption and allows a fine resolution. Nevertheless, the purchase and maintenance costs of excimer lasers are expensive.
The Nd:YAG laser is a solid-state laser. Its lasing action is developed in Yttrium Aluminium Garnet (YAG) crystal which is host to the neodyum (Nd3+) ion. It is based on a four-level system of electron energy level changes within the ion. Nd:YAG lasers are optically pumped by lamps or diode lasers mainly emitting at 810 nm. This laser can produce high power in the near infrared, at a 1064 nm wavelength.
They are used for cutting, welding, and marking of metals and other materials. These lasers are also frequency doubled, tripled or quadrupled to produce 532 nm (green, visible), 355 nm and 266 nm (UV) beams, respectively. Furthermore, others solid-state lasers with dopants like ytterbium, holmium, erbium, or another material association like titanium-sapphire are available on the market.
Since the discovery of lasers, CO2 lasers have been the most employ in the material processing industry. The emission of carbon dioxide lasers results from an electric discharge maintained in a gas mixture of carbon dioxide, nitrogen, and helium. The classical wavelength of emission is in the infrared, around 10.6 μm, but lower wavelengths are now being used for processing specific polymers.
CO2 lasers offer a high average power output; from a few Watts up to 50 kilowatts. CO2 lasers are currently used in the automotive industry in other steel parts manufacturing activities. A CO2 laser is also an ideal tool for industrial laser marking, annealing, and engraving. It can also be used to weld metals, plastics or to mark wood. While providing excellent beam quality, they offer a much weaker electrical-to-optical conversion efficiency (<10%) hence leading to higher operating costs than fiber lasers.