Semiconductor lasers, commonly known as laser diodes, are called semiconductor laser pointers because of their properties as semiconductor materials. The semiconductor laser is composed of a fiber-coupled semiconductor laser module, a combination device, a laser energy transmission cable, a power supply system, a control system, and a mechanical structure, and realizes laser output under the driving and monitoring of the power supply system and the control system. Common working materials for semiconductor lasers include gallium arsenide (GaAs), cadmium sulfide (CdS), indium phosphide (InP), and zinc sulfide (ZnS). There are three main types of excitation depending on the working substance: electric injection, pump type and high energy electron beam excitation.
(1) Electro-injection is a semiconductor laser. Generally, a working material such as GaAS, CdS, InP, or ZnS is used as a main material to form a semiconductor junction-type diode. When subjected to electrical injection, a current injected along a forward bias is applied. The working substance is excited to generate stimulated emission in the plane of the section.
(2) Punp-type lasers, generally consisting of a hole-bearing germanium single crystal (P-type semiconductor single crystal) or an electron-bearing germanium single crystal (N-type) doped with an acceptor impurity in the crystal. The semiconductor single crystal is used as a working substance, and is excited by a laser emitted from another laser to realize population inversion.
(3) High-energy electron beam excitation semiconductor laser pointer, generally similar to pump laser in the selection of working materials, is also a semiconductor germanium single crystal, but the problem worth noting is that high-energy electrons are selected in the selection of P-type semiconductor single crystals. Beam-excited semiconductor lasers are mainly PbS. CbS and ZnO are dominant.
There are many types of semiconductor lasers, and there are many classification methods depending on their chip parameters and packaging methods. Among them, the classification of semiconductor lasers for optical fiber output mainly includes the following:
Since the invention of the world's first semiconductor laser in 1962, semiconductor lasers have undergone tremendous changes, greatly promoting the development of other science and technology.
In recent years, the small power semiconductor laser pointer used in the field of information technology has developed extremely fast. For example, DFBs for dynamic fiber communication and dynamic single-mode laser diodes, as well as laser diodes of visible wavelengths that are widely used in optical disk processing, and even ultrashort pulse laser diodes have undergone significant innovations.
Low-power laser diodes also have this highly integrated, high-rate, and tunable development feature. The development speed of large high-power semiconductor lasers is also accelerating.
In the 1980s, the output power of independent laser diodes was already above 100mW and achieved a conversion efficiency of 39%. By the 1990s, the Americans once again raised the indicator to a new level, achieving a conversion efficiency of 45%. In terms of output power, it also changed from W to KW.
At present, with the support of research projects in various countries, the laser technology of semiconductor laser chip structure, epitaxial growth and device packaging has made great progress, and the performance of unit devices has also achieved a major breakthrough: the electro-optical conversion efficiency is over 70%, very low. The beam divergence angle, continuous output power of single bar exceeds kW, and the carbon nano- (CN) heat sink can increase the cooling efficiency of the laser by 30% compared with the traditional semiconductor bar mounting technology. The 100μm strip width single tube output power reaches 24.6W, and the high power continuous working life is up to tens of thousands of hours.
High-performance and high-power semiconductor lasers have also rapidly developed into fully-cured laser pointer, giving LDP solid-state lasers new opportunities and prospects.