Technology Development And Application Fields Of Semiconductor Lasers

1. Introduction to Semiconductor Lasers
Semiconductor lasers are commonly known as laser diodes, because they use semiconductor materials as the working material, so they are called semiconductor lasers. The semiconductor laser is composed of a fiber-coupled semiconductor laser module, a beam combining device, a laser energy transmission cable, a power supply system, a control system and a mechanical structure, etc., and realizes laser output under the drive and monitoring of the power supply system and control system. The commonly used working substances of semiconductor lasers mainly include gallium arsenide (GaAs), cadmium sulfide (CdS), indium phosphide (InP), zinc sulfide (ZnS), etc. According to different working substances, there are three main excitation methods: electric injection, pump and high-energy electron beam excitation.

(1) Electrically injected semiconductor lasers generally use GaAS, CdS, InP, ZnS and other working substances as the main materials to make semiconductor surface junction diodes. When receiving electrical injection, the current injected along the forward bias is The working substance is excited to produce stimulated emission in the nodal plane region.
(2) Punp-type lasers, generally composed of germanium single crystals with holes as carriers (P-type semiconductor single crystals) or germanium single crystals with electrons as carriers (N-type semiconductors) doped with acceptor impurities in the crystal. Semiconductor single crystal) is used as the working material, and the laser emitted by other lasers is used as pump excitation to realize population inversion.
(3) High-energy electron beam-excited semiconductor lasers are generally similar to pump-type lasers in the selection of working materials, and semiconductor germanium single crystals are also used. However, it is worth noting that high-energy electron beams are used in the selection of P-type semiconductor single crystals. Excited semiconductor lasers are mainly based on PbS. CbS and ZnO are the main ones.

2. Diode Laser Market Size

Semiconductor lasers have the advantages of small size, light weight, long life, high operational reliability, low energy consumption, high electro-optical conversion efficiency, easy mass production, and low price. Printers, etc. are widely used, covering the entire field of optoelectronics.

With the continuous development and breakthrough of technology, semiconductor lasers are developing in the direction of shorter emission wavelength, higher emission power, ultra-small size, and long life, so as to meet the needs of various applications, and the product categories are becoming more and more abundant. It has also been widely used in laser processing, 3D printing, laser radar, laser ranging, military, medical and life sciences. In addition, by coupling into optical fiber for transmission, high-power direct semiconductor lasers have been widely used in the fields of cutting and welding.

3. Application of semiconductor lasers in the field of optoelectronics
(1) Optical fiber communication. Semiconductor laser is the only practical light source for optical fiber communication system, and optical fiber communication has become the mainstream of contemporary communication technology.
(2) CD access. Semiconductor lasers have been used in optical disk storage, and its greatest advantage is that the amount of stored sound, text and image information is very large. The use of blue and green lasers can greatly improve the storage density of optical discs.
(3) Spectral analysis. Far-infrared tunable semiconductor lasers have been used in environmental gas analysis, monitoring air pollution, vehicle exhaust, etc. It can be used in industry to monitor the process of vapor deposition.
(4) Optical information processing. Semiconductor lasers have been used in optical information systems. Two-dimensional arrays of surface-emitting semiconductor lasers are ideal light sources for optical parallel processing systems, which will be used in computers and optical neural networks. 5) Laser microfabrication. With the help of high-energy ultra-short light pulses generated by Q-switched semiconductor lasers, integrated circuits can be cut and drilled.
(5) Laser alarm. Semiconductor laser alarms are widely used, including anti-theft alarms, water level alarms, and vehicle distance alarms.
(6) Laser printers. High power semiconductor lasers are already used in laser printers. The use of blue and green lasers can greatly improve printing speed and resolution.
(7) Laser barcode scanner. Semiconductor laser barcode scanners have been widely used in the sales of goods, and the management of books and files.
(8) High definition laser TV. In the near future, semiconductor laser TVs without cathode ray tubes can be put on the market. It uses red, blue and green lasers, and its power consumption is estimated to be 20% lower than that of existing TVs.

4. Where is the future of semiconductor lasers?

At present, the largest application of semiconductor lasers is as a pump source for fiber lasers and solid-state lasers. When the semiconductor laser is used as the pump source of the fiber laser, the structure of the pump system can be fundamentally simplified by increasing the unit power, and the pump power level can be increased. As fiber lasers and solid-state lasers have higher and higher output power requirements, higher requirements are also placed on the power of semiconductor pump sources.

Due to the limitation of beam quality, it is difficult for traditional semiconductor lasers to be directly used for metal cutting. In recent years, with the improvement of semiconductor coupling technology and the gradual maturity of new beam combining technology, some semiconductor lasers with fiber output above kilowatts can also meet the requirements of cutting beam quality. In addition, due to the diversity of semiconductor laser wavelengths, the wavelength of short-wavelength semiconductor lasers is very close to the wavelength absorption maximum of aluminum. Therefore, in the automobile industry, high-power semiconductor lasers are very suitable for welding aluminum automobile bodies. At present, semiconductor lasers with a laser output power between 2KW and 6KW have been widely used in the production process of the automobile industry.

In the field of direct material processing, the beam quality of semiconductor lasers is difficult to surpass that of fiber lasers. However, in thin plate welding and cutting applications, semiconductor lasers are very suitable. The development of high-power semiconductor lasers has enabled many important applications. These lasers have replaced many traditional technologies and brought us many new products.

Generally speaking, due to the continuous development of technology, the application fields of semiconductor lasers are constantly changing, and these changes are still happening. In general, semiconductor lasers are developing towards shorter emission wavelengths and higher emission powers to meet current market demands.

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