Semiconductor lasers are also called laser pointer diodes (LD). With the development of semiconductor physics, people imagined the invention of semiconductor lasers as early as the 1950s.
The semiconductor laser in the early 1960s was a homogeneous junction laser, a type of semiconductor laser that could only work in pulse form. At the International Conference on Solid-State Device Research held in July 1962, two scholars Keyes and Quist from the Lincoln Laboratory of Massachusetts Institute of Technology reported the light emission phenomenon of gallium arsenide materials.
The second stage of semiconductor laser development is a heterostructure semiconductor laser, which is a laser composed of two thin layers of semiconductor materials with different band gaps, such as GaAs and GaAlAs. The single heterojunction implanted laser (SHLD) is a laser engraver that uses the potential barrier provided by the heterojunction to limit the injected electrons within the P region of the GaAsP-N junction to reduce the threshold current density.
In 1970, people invented a double heterojunction GaAs-GaAlAs laser with a laser wavelength of 9000 Å that works continuously at room temperature. Among the semiconductor laser devices, it is currently relatively mature, with better performance and applications. The more widely used is the electrically injected GaAs diode laser with double heterostructure.
The energy level with the lowest energy in an atom is called the ground state, and the energy level higher than it is called the excited state. If electrons can achieve energy transition, from a high-energy state to a low-energy state, this process will radiate a photon outward. But this is the most basic principle of generating radiant light.
Compared with ordinary light, laser has the following characteristics, such as high collimation, single frequency, good correlation, and high brightness. Such special conditions certainly require more requirements to achieve it. This is the other conditions we mentioned above.
Since the end of the 1970s, semiconductor lasers have clearly developed in two directions. One type is information blue laser pointer for the purpose of transmitting information; the other type is power lasers for the purpose of increasing optical power. Driven by applications such as pumped solid-state lasers, high-power semiconductor lasers (continuous output power above 100W, pulse output power above 5W, can be called high-power semiconductor lasers) made breakthrough progress in the 1990s , Its sign is that the output power of semiconductor lasers has increased significantly. Foreign kilowatt-level high-power semiconductor lasers have been commercialized, and the output of domestic sample devices has reached 600W. In addition, there are high-power aluminum-free lasers, infrared semiconductor lasers, and quantum cascade lasers. Among them, the tunable semiconductor laser changes the wavelength of the laser through an external electric field, magnetic field, temperature, pressure, doping basin, etc., which can easily modulate the output beam.