The laser was first successfully manufactured in 1960. Laser was born under the background of the urgent need of theoretical preparation and production practice. As soon as it came out, it achieved an extraordinary rapid development. The development of laser not only gave birth to the ancient optical science and optical technology, but also caused The emergence of an entire emerging industry. Lasers enable people to effectively use unprecedented advanced methods and means to obtain unprecedented benefits and results, thereby promoting the development of productivity.
However, laser laser cutting, laser welding
has been widely used in daily life production, and laser crystals such as laser crystals, terahertz and so on. laser technology.
Laser crystals Laser crystals can convert externally provided energy through optical resonators into spatially and temporally coherent, highly parallel and monochromatic laser crystalline materials. It is the working substance of crystal laser. The laser crystal is composed of two parts, the luminous center and the host crystal. The emission center of most laser crystals is composed of activating ions, which partially replaces the cations in the host crystal to form a doped laser crystal. When the activated ions become part of the matrix crystal component, they form a self-activated laser crystal.
The active ions used in laser crystals are mainly transition metal ions and trivalent rare earth ions. The optical electrons of transition group metal ions are 3d electrons in the outer layer. This optical electron is susceptible to the direct action of the surrounding crystal field in the crystal. Therefore, the crystal characteristics of crystals with different structure types are very different. The 4f electrons of trivalent rare earth ions are shielded by the outer electrons of 5s and 5p, making the crystal field weaken its effect, but the perturbation of the crystal field makes the forbidden 4f electron transition possible, resulting in narrow-band absorption and fluorescence Spectrum lines. Therefore, the spectrum of trivalent rare earth ions in different crystals does not change as much as the transition group metal ions.
The host crystals used in laser crystals are mainly oxides and fluorides. In addition to the matrix crystal, its physical and chemical properties are stable, large-size crystals with good optical uniformity are easy to grow, and the price is cheap, but the adaptability between it and activating ions must be considered, such as the radius of the cations of the matrix and the activating ions, the charge Sex and valence should be as close as possible. In addition, the influence of the host crystal field on the spectrum of the activated ion must be considered. For some matrix crystals with special functions, the active ion can be directly used to generate a laser with certain characteristics. For example, in some non-linear crystals, the activated ion can directly convert into a harmonic output after the laser is generated by the matrix crystal.