What is a Tunable Laser?

Larry Ray Palmer

A tunable laser is a type of laser diode that can be adjusted to produce a variable wavelength or frequency. This adjustable function allows the laser to be used for more than one purpose and allows the operator more control over the function of the tunable laser than that which is possible with traditional laser units. The adjustment regions of the tunable laser range from the infrared to visible and ultraviolet light emissions. In theory, tunable lasers could eventually be able to change frequencies or wavelengths in the individual packets of a transmission, rather than in grouped packets as laser tuning is done currently.

A tunable laser cutter is used to cut a sheet of metal.
A tunable laser cutter is used to cut a sheet of metal.

The first tunable lasers were dye lasers, discovered in 1966. By introducing dye to the beam of a laser, researchers were able to tune the wavelength of the light emitted by the laser. The dye laser offers an extremely large bandwidth of emitted light frequencies, thus making this tunable laser type one of the widest ranging. In some instances, the laser's beam is intercepted again and again by different prisms, dyes, and diffraction gratings to further tune or isolate a certain desired wavelength.

The tunable laser has proven useful in the field of medicine.
The tunable laser has proven useful in the field of medicine.

By using various prisms, diffraction gratings, and dyes, the first tunable lasers were demonstrated in the lab and further study of the technique continued. This research has been further expanded to include a broad range of laser research and applied technology. There are now four classifications of tunable lasers: single line, multi-line, narrowband, and widely tunable.

The use of tunable laser technology is seen in various applications. Spectroscopy and photochemistry both make use of tunable lasers to study chemical compositions and the effect of light on the chemicals being studied. Optical communications, or fiber optic communications, also use tunable lasers and related technology to perform various functions. These lasers are even used to separate isotopes of uranium to use as fuel for nuclear power plants in a process called atomic vapor laser isotope separation (AVLIS).

The tunable laser has seen moderate use in the field of industry. Used in cutting, welding, and burning applications, it is beginning to see more use as the price of the technology drops into an economically feasible range for many industries, such as metalworking and electronics. The tunable laser has also proven useful in the field of medicine, providing precision laser surgery and other medical treatments or testing that would have been impossible without this technology.

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