YAG window crystals Yttrium Aluminum Garnet

MgF2 or Magnesium Fluoride is positive uni-axial crystal with a very high optical transmittance from the vacuum UV to IR. It is regularly used for optical elements where extreme ruggedness and durability is required. It also has a large resistance to mechanical and thermal shock, to optical radiation, and is chemically stable, making it a very useful materials for UV and IR optics.

CaF2 or Calcium Fluoride is a cubic crystal with an excellent transmission from 130 nm to 10 μm and has widespread applications as transparent windows in the ultraviolet and infrared spectra.

HGO grows LiF crystals in house using Czochralski technology. LiF crystal or lithium fluoride crystal is an optical material with outstanding transmittance in VUV region. It is also used for windows, prisms, and lenses in the visible and infrared in 0.104µm-7µm. LiF single crystal is sensitive to thermal shock and would be attacked by atmospheric moisture at 400°C. When working at a high temperature of 600°C, the LiF crystal softens and is slightly plastic, so it can be bent into radius plates. In addition irradiation produces color centers. Hence, users should take measures to protect LiF crystals from moisture and high energy radiation damages. What is more LiF can be cleaved along (100) plane and less commonly (110) plane. The optical characteristics are good and yet the structure is not perfect and cleavage is difficult.

YbYAG crystal is more suitable for diode-pumping than the traditional Nd-doped systems. It can be pumped at 0.94 μm laser output. Compared with the commonly used Nd:YAG crystal, Yb:YAG crystal has a much larger absorption bandwidth to reduce thermal management requirements for diode lasers, a longer upper-state lifetime, three to four times lower thermal loading per unit pump power. Yb:YAG crystal is expected to replace Nd:YAG crystal for high power diode-pumped lasers and other potential applications.

Silicon is used as an optical window primarily in the 3 to 5 micron band and as a subsrate for production of optical filters and windows. Silicon (Si) is grown by Czochralski pulling techniques (CZ) and contains some oxygen that causes an absorption band at 9 microns. To avoid this, material can be prepared by a Float-Zone (FZ) process. Optical silicon is generally lightly doped (5 to 40 ohm cm) for best transmission above 10 microns, and doping is usually boron (P-type) and phosphorus (N-type). After doping silicon has a further pass band: 30 to 100 microns which is effective only in very high resistivity uncompensated material.

Non-Polarizing Cube Beamsplitters also called NPBS Cube is a more sophisticated type consisting of two right- angle prisms cemented together at their hypotenuse faces.The cemented face of one prism is coated. Before cementing, with a metallic or dielectric layer having the desired reflecting properties, both in the percentage of reflection and the desired color. The absorption loss to the coating is minimal and transmission and reflection could be designed to 10%, 20%, 30%, 40%, 50%, etc.

Diffusion bonded crystals consist of one laser crystal and one or two undoped material. They are combined by optical contact method and further bonded under high temperature. Diffusion Bonded Crystal helps to decrease thermal lens effect considerably of laser crystals, provides integral components to make compact lasers. HGO are able to supply various standard assembly and special customized bonding crystals.These diffusion bonded composite crystals have different wedge structures, Brewster angles, etc. It is used to effectively reduce the thermal effect of solid-state high-power lasers.

Sapphire window retains its high strength at high temperatures, has good thermal properties and excellent transparency. It is chemically resistant to common acids and alkali at temperatures up to 1000 °C as well as to HF below 300 °C. These properties encourage its wide use in hostile environments where optical transmission in the range from the vacuum ultraviolet to the near infrared is required.