Features & Applications of Semiconductor Lasers

        Laser is an unnatural light produced through the theory of stimulated emission of radiation. Lasers cannot exist in nature because the generation of lasers needs to be completed in an optical resonant cavity. The working material obtains energy and jumps to a high energy level and releases photons. The emitted photons are reflected back in the resonant cavity and generate stimulated radiation with high-energy level particles again. This produces laser light.

      The laser beam generated by the above principle has many characteristics that ordinary light sources do not have.

1. Features/characteristics of laser:

a. Good monochromaticity: The wavelength of light emitted by the gallium arsenide laser is 650nm, the laser wavelength range is ±3nm, and the beam is almost monochromatic.

b. Good coherence: Laser has a high degree of coherence. There is a certain phase relationship between light waves. It has good temporal coherence (~10 - 8 Angstroms). The coherence length can reach tens of kilometers. It has good spatial coherence. Some lasers Every point on the wave surface is a coherent light source.

c. Good directivity: The laser beam is very concentrated, with a divergence angle of approximately 0.6mrad. It has strong directivity and can be transmitted over long distances.

d. High energy density: Laser has high energy density and can instantly increase laser energy to 80,000 watts through pulse energy.

      Based on the above characteristics, laser has important applications in many fields, including the following aspects.

2. Application of laser:

a. Medical applications: In medical applications, lasers can be used for surgery, improvement of myopia, internal lighting diagnosis, fluorescence excitation, and cosmetic applications.

b. Communication applications: In fiber optic communication systems, lasers are widely used as light transmitters. Lasers simulate signals and perform high-speed data transmission. Infrared lasers can also be used to transmit optical signals wirelessly.

c. Material processing applications: Laser can perform fine processing, engraving, marking, welding and cutting on a microscopic scale without contact. Especially in automated material processing, such as machine vision systems, we can often see the word "一" Line laser, grid laser, and multi-line laser assist visual inspection. There are also subdivided applications such as laser collimation, laser positioning, and laser ranging.

d. Scientific research application: A large number of optical pumps are needed to expand the research of spectral analysis, which also promotes the progress of lasers in the fields of interference, diffraction and laser interferometry.

e. Military applications: military guidance, laser weapons and other military applications.

f. Entertainment applications: laser shows, laser performances, laser imaging and other entertainment applications.