The origin and development of laser devices
The light source needed for optical fiber communication should be the light source that can be modulated at high speed to carry large capacity information. Such as lasers and tubes. The so-called “modulation” is according to the information to be transmitted to change the intensity of light, etc., to carry information.
Maimen invented the ruby laser in 1960. The difference between Laser (Laser source) and ordinary light mainly lies in that the optical frequency of Laser is very simple and has linear spectral lines. Known as coherent light in optics, it is the most suitable light source for optical fiber communication. Normal light, on the other hand, has a very messy frequency, which includes many wavelengths. Normal light, on the other hand, has a very messy frequency, which includes many wavelengths. The characteristic of coherent light is that it is concentrated and has a small divergence Angle. After the invention of ruby laser, a variety of lasers were born: gas lasers, such as he-ne laser; There are solid-state lasers, such as YAG iridium aluminum garnet lasers; There are chemical lasers; Dye laser and so on. Among them, semiconductor laser is the most suitable light source for optical fiber communication. Its volume is small, efficiency is high, and its wavelength is suitable for the low loss window of optical fiber.
However, the manufacturing process of semiconductor lasers is very complicated. It requires epitaxial growth of 5 layers of doped semiconductors on the substrate material with extremely high purity and no defects. At the end of the 1970s, a semiconductor laser with a long continuous working life at room temperature was finally made. In 1976, the world’s first practical fiber optic communication line was built from Atlanta to Washington. At this time the semiconductor laser has not yet pass, the light source is the use of semiconductor luminous tube. In the early 1980s, single-mode fiber and laser have been mature, since the advantages of fiber communication large capacity gradually play.
Application of laser
With its excellent performance and low price, laser has been widely used in optical fiber communication, optical fiber sensing, industrial processing, medical treatment, military and other fields.
In terms of communication, the 1.30 micron and 1.55 micron laser provided by the laser are two low loss Windows for communication. The laser can not only produce continuous laser output, but also realize the generation of ps-fs ultra-short optical pulse, which has a huge potential application in DWDM system. The laser makes the communication system have higher transmission speed and longer transmission distance, which plays an irreplaceable role.