The commercial and industrial use of laser diodes has dramatically increased recently. The optical characteristics, small size, and ruggedness of laser diodes have allowed many new uses to be commercialized.
The output of laser diodes is very bright considering their small size. Today, hundreds of watts of power are commercially available from laser diodes operating under continuous wave (CW) conditions in packages as small as a few cubic inches. This characteristic makes these devices suitable for cable TV transmission, high definition TV (HDTV) development, and medical applications.
In addition, compared to other types of lasers, laser diodes use very little power. Most laser diodes operate with voltage drops of less than 2 V with power requirements determined by their current setting. Overall efficiencies greater than 30% are typical in the case of laser diodes. Since laser diodes are made of semiconductor materials, they do not require the fragile glass enclosures or mirror alignment typical of gas lasers. The resulting ruggedness and small size allow laser diodes to be used in environments and spaces in which other types of lasers cannot operate.
Coherence and single wavelength characteristics of laser diodes enable the outputs of these devices to be focused to a diffraction limited spot size. The size of the resultant spot is dependent on the wavelength of the laser – the shorter the wavelength of light, the smaller the size of the spot that can be generated. Operation at shorter blue and UV wavelengths makes smaller spot sizes possible, consequently allowing more information to be stored on optical disks at a higher density.
Another advantage of laser diodes is that they can be directly modulated at high frequencies. By modulating the drive current, the output of the laser diode is modulated with frequencies up to several GHz in high-speed data communications.