In the mid-nineties of the last century, the use of quartz on the end face of the optical fiber ushered in an important step in the development of optical fiber technology. The larger surface achieves a lower power density, which not only improves the mechanical installation, but also reduces the loss caused by the anti-reflection (AR) coating.
In automotive body welding applications, the fiber with a core diameter of 600 μm once represented the most advanced level. As the beam quality has been significantly improved, diode-pumped solid-state laser pointer require the core diameter to be reduced to 300-400 μm.
Today, Optoskand fibers with a core diameter of 50 μm to 1 mm, with low loss and high reliability, have been widely used. One of the oldest designs of well-known solid-state lasers is to use Nd:YAG crystal rods as gain media. Until the end of the 1990s, these crystals were pumped with flashlamps.
This type of laser has an electro-optical conversion efficiency of only 3%, and the lifetime of the flash lamp is about 1000 to 2000 hours. All laser experts hope to replace flash lamps with laser diodes. Laser diodes have the following two major technical advantages: higher efficiency and lower thermal load, better overall efficiency and improved beam quality.
Acquired the Semiconductor Laser Company in 1997, and only one year later launched the first diode-pumped solid-state green laser pointer of several kilowatts. These lasers can achieve a higher efficiency of about 10%, a beam quality of 12 mm? mrad and a longer life of the excitation module. The next technological development is to change the shape of the gain medium from rod-shaped to disc-shaped to provide an overall efficiency higher than 20% and a better beam quality of about 5mm?mrad.
In addition to the service life of the pump module, an important issue in the field of solid-state lasers is how to effectively remove the heat in the laser gain medium. If the typical gain medium is a rod-shaped solid-state laser, the beam quality is significantly affected by the radial thermal gradient, which is the so-called "thermal lens effect." The use of a disc-shaped gain medium can reduce the thermal lens effect because it can implement efficient large-area heat dissipation on the back of the disc, thereby producing a continuous and consistent high beam quality. During 2003-2010, it provided high-power disc lasers for industrial cutting and welding applications.