Nd:YVO4 is the most efficient laser host crystal for diode pumping among the current commercial laser crystals, especially, for low to middle power density. This is mainly for its absorption and emission features surpassing Nd:YAG.
Nd:YAG is the earliest and most famous laser host crystal. Since it combines great advantages in many basic properties, Nd:YAG is the ubiquitous presence for near-infrared solid-state lasers and their frequency-doubler, tripler, and higher order multiplier.
Neodymium doped Potassium-Gadolinium Tungstate crystals (Nd:KGd(WO4)2 or Nd:KGW) is an excellent laser gain material which has low laser oscillations threshold and higher emission section. The fluorescent concentration quench effect of the Nd3+ ion in the KGW crystal may be weakened due to the W-O covalent bond, so this crystal has a higher doping concentration of active ion. Furthermore, the absorption band at 808nm of Nd3+ in the KGW which has 12nm FWHM is well matched with the emission wavelength of current commercial laser diode.
CASTECH grows Nd:YLF crystals using Czochralski method. The use of high quality starting materials for crystal growth, whole boule interferometry, and precise inspection of scattering particle in crystal using He-Ne laser assures that each crystal will perform well.
Yb:CaGdAlO4(called CALGO) is a promising new laser gain material which possess several important advantages. The crystal structure of CALGO is tetragonal. When it is pumped at 979nm under pi configuration, we can get broad emission spectra from 994nm to 1050nm in theta configuration. This implies a very small quantum defect (down to 1.5%) and gives a good expectation of obtaining ultra-short pulse. Its thermal conductivity is also high: k=6.7W/m/K, which means it can be used for high power laser applications.
Yb:YAG is one of the most promising laser-active materials and more suitable for diode-pumping than the traditional Nd-doped systems. 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-laser level lifetime, three to four times lower thermal loading per unit pump power. Yb:YAG crystal at 1030nm is a good substitute for a Nd:YAG crystal at 1064nm and its second harmonic at 515nm may replace Ar-ion laser (with a large volume), which emit at 514nm.
Ytterbium-doped Calcium fluoride, grown by Czochralski technique, is with long fluorescence lifetime and broad absorption bands, which make it an ideal material for laser diode pumping. Yb3+:CaF2 exhibits broad emission bandwidth as well as limited non-linear effects under intense irradiation, supporting generation of ultra-short pulses and high-power operation.
Ytterbium doped Potassium-Gadolinium Tungstate crystals - (Yb:KGd(WO4)2 or Yb:KGW) is an excellent laser gain material which has important advantages over the widely used Nd3+ doped materials. Its broad spectral emission band 1023-1060nm allows the generation of short (ps or fs) laser pulses. Its wide absorption spectrum at 980 nm and high absorption of pump radiation allow an efficient use of diode laser pumping. Compared with YAG used as hosts for Yb3+, KGW has the advantage of larger absorption cross section, which decreases the minimum pump intensity necessary to achieve transparency in the quasi-two-level system of ytterbium.