What Is a Semiconductor Laser?
A semiconductor laser uses a semiconductor as the medium for laser oscillation. Laser light is emitted when an electric current is applied. It is also commonly referred to as a laser diode.
As laser oscillators, they are currently used in many devices.
The reasons for their use in various fields are that they are compact as lasers, can oscillate at low voltages and currents, have high conversion efficiency to light, and are easy to produce lasers of different wavelengths.
Uses of Semiconductor Lasers
Semiconductor lasers have a wide range of applications, however, the fields in which they can be used depend on the wavelength and output power of the laser light.
For example, the wavelength of light is closely related to the intensity of energy.
For example, a laser with a long wavelength and low energy is used in sensors such as automobile collision prevention, optical measuring instruments, and laser communications.
On the other hand, lasers with shorter wavelengths and higher energy are used for writing on Blu-ray and DVDs, printers, and laser processing.
Principle of Semiconductor Lasers
Semiconductor lasers are able to emit light efficiently because they can generate it by passing an electric current through them. This differs from incandescent light bulbs, which convert electric current into thermal energy.
Simply put, the inside of semiconductor lasers consists of layers called the P-type region, the light-emitting layer (active layer), and the N-type region between the electrodes.
When an electric current flows from the electrodes, holes (holes) from the P-type region and electrons from the N-type region flow into the light-emitting layer.
The holes and electrons combine in the light-emitting layer and emit light. However, at this stage, the light does not have the characteristics of laser light.
The emitted light stimulates other electrons, and the stimulated electrons combine with holes to emit light. This is called induced emission.
The light is reflected by mirrors in the generator layer, which further stimulates induced emission, and the light is amplified to become a strong laser beam that is emitted externally.
In recent years, semiconductor lasers have become more and more sophisticated. The luminous efficiency of semiconductor lasers has been remarkably improved.