LiF crystal lithium fluoride

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.

Pure YAG Yttrium Aluminum Garnet is a new substrate and window material that can be used for both UV and IR optics. It is particularly useful for high-temperature and high-energy applications. The mechanical and chemical stability of YAG is comparable to sapphire crystal, but YAG is unique with no birefringence which is extremely important for some optical applications.

Ti:Sapphire crystal is the most widely used tunable solid-state laser material combining the supreme physical and optical properties with the extremely broad lasing range. Its lasing bandwidth can support pulses < 10fs making it the crystal of choice for femtosecond mode-locked oscillators and amplifiers. The absorption band of Ti:Sapphire centers at ~ 490 nm so it may be conveniently pumped by various laser sources such as argon ion lasers or frequency doubled Nd:YAG, Nd:YLF, Nd:YVO4 lasers at ~530nm. Laser designers are using Ti:sapphire to generate femtosecond pulses to create new industrial tools. A properly delivered femtosecond laser pulse interacts within the target leaving the surrounding area undisturbed. Newly developed femtosecond pulsed lasers micro-machine complex fine structures in glass, metal and other materials. Active waveguides can be written below the surface, integrating optical devices within the body of a substrate. Defects in photomasks can be repaired without disturbing neighbouring patterns. And it is now possible to achieve cellular resolution in vivo for medical diagnosis with femtosecond pulse lasers.

α-BBO (α-BaB2O4) is a negative uniaxial crystal which has large birefringence over a broad transparent range of 190nm to 3500nm. α-BBO is an excellent crystal especially in UV and high power applications. The physical, chemical, thermal, and optical properties of alpha-BBO crystal are similar to those of Beta-BBO. However, there is no second order nonlinear effect in alpha-BBO crystal due to the centrosymmetry in its crystal structure and thus it has no use for second order nonlinear optical processes. Instead, alpha-BBO is widely used for fabrication of polarizers, polarizing beam displacers, phase retarders, birefringent plates, and time delay compensators especially those for UV and high power lasers.

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.

KDP Potassium Dihydrogen Phosphate and KD*P or DKDP Potassium Dideuterium Phosphate are among the most widely-used commercial NLO materials, characterized by good UV transmission, high damage threshold, and high birefringence, though their NLO coefficients are relatively low. They are usually used for doubling, tripling and quadrupling of a Nd:YAG laser under the room temperature. In addition, they are also excellent electro-optic crystals with high electro-optic coefficients, widely used as electro-optical modulators, such as Q-switches, Pockels Cells, etc.

HGO grows Ho:YLF laser crystals using Czochralski technology. Ho:YLF is a very attractive laser material, because the lifetime of the upper laser level is much longer ( ~ 14 ms) than in Ho:YAG and the emission cross sections are higher. Additionally the thermal lens in Ho:YLF is much weaker, which helps to generate diffraction limited beams even under intense end-pumping. The primary advantage of directly pumping the Ho 5I7 is that it does not have to depend on energy transfer, which lends itself to various radiative and non-radiative losses. Up-conversion losses that have deleterious effect in high-energy Q-switched lasers are eliminated.