Do you have a DVD or CD player or even a printer? How about a remote control that operates your TV? Each of these household items has a laser diode. This is a semiconductor device that emits waves of the same frequency and phase when power flows through them. The light beams emitted by laser diodes are not the pencil-shaped beams capable of mass destruction that you may be imagining. Rather, they emit wider cone-shaped beams of visible or infrared light. They are low intensity beams. They are tiny devices, typically less than a millimeter in diameter, with minimal power requirements. A glass wafer with p-type and n-type regions is a feature of these, and it is this feature that classifies them as semiconductors rather than solid-state lasers.
Diodes are similar to LEDs. In fact, LEDs have been described as lasers without feedback cavities. Laser diodes have internal or external feedback cavities that are used to trigger the action of the laser. High Q cavities narrow the emission lines and beams. These beams are not as sharp or narrow as gas laser beams.
laser light and colors
These emit visible or infrared light. Colors range from blue, blue-violet, and green to red. The use of the laser diode depends largely on its wavelength and position in the light spectrum. For example, Blu-ray Disc players use 405 nm blue-violet laser diodes, while red laser pointers use laser diodes in the 635 nm range.
common uses
Tiny in size and rugged, laser diodes are the most common type of laser. They are found in the items mentioned above, as well as barcode scanners, fiber optics, optical mice, rangefinders, laser pointers, and medical equipment.
Security issues
While they are not as dangerous as gas or solid-state lasers, they must be used with care. In some cases, such as CD and DVD players, the laser diodes are housed within the unit and are not intended to be seen. Also, its low output beams are nearly invisible and highly divergent. By contrast, laser pointers have higher performance and are highly visible. Laser pointers are collimated and it is possible for high powered laser pointer beams to burn the retina of an eye. Laser pointers can also cause less substantial effects such as headaches, afterimages, and visual distraction when not used correctly.
A greater danger is associated with the higher power visible and infrared diode lasers. Even invisible rays can be dangerous if they are collimated. Due to the possibility of injury or burns to the eyes, care is prudent whenever a diode laser is present. Never look into a laser beam or point a laser pointer at another person’s eyes. Also be careful of reflected laser beams.
Small, powerful and useful, they have become increasingly common. In many cases, you will never see the lightning, but you should be aware of it and avoid the temptation to look at it or alter it in any way.