The laser matrix crystals must have good transparency, especially the absorption of the laser wavelength should be as low as possible. The high transparency of the high precision optical waveplate allows the energy of the optical pump to be sufficiently absorbed by the activated ions to be converted into a laser. A decrease in transparency increases the absorption of the optical pump energy by the substrate and increases the temperature of the laser crystal, which brings a series of disadvantages. At present, the radiation band of the optical pump is mostly located in the visible light and near ultraviolet and infrared regions, so it is necessary to select materials that are transparent in this region. It is preferred to use an oxide and a fluoride crystal in the inorganic crystal. a compound containing transition metal elements such as iron, copper, lead, manganese, diamond, nickel, etc. in the matrix crystal. Strong absorption in the near ultraviolet to infrared will reduce the transparency of the high-quality laser grade optical waveplate. The main source of laser wavelength absorption in the crystal is impurities.
Laser crystals must have good optical uniformity. The optical non-uniformity of the laser crystal causes the wavefront to deform and generate a path difference after passing through the crystal, which causes the oscillation threshold to improve the efficiency and the divergence angle to increase.
Laser crystals must have good thermal stability. During operation of the laser, the non-radiative transition loss of the activated ions and a portion of the optical energy of the ultraviolet and infrared absorption light pump of the matrix crystal are converted into thermal energy that raises the temperature of the crystal. At the same time, temperature gradients occur in the radial direction of the rod due to differences in endothermic and cooling conditions. In addition to causing a decrease in the optical uniformity of the laser crystal to affect the laser performance, these factors may even cause the laser to be damaged by the poor thermomechanical properties.
Laser crystals must have good physicochemical properties. In addition to the above requirements, in order to facilitate manufacturing, processing and use, laser crystals are also required to have good physical properties. This includes a small tendency to devitrification and high chemical stability. Have a certain mechanical strength and good light stability and thermal conductivity. A optical waveplate manufacturer having a high degree of devitrification tends to cause crystal production, especially a large crystal production process, and it is difficult to obtain a crystal having high optical uniformity.