LBO (Lithium Triborate – LiB3O5) is now the most popularly used material for Second Harmonic Generation (SHG) of 1064nm high power lasers (as a substitute to KTP) and Sum Frequency Generation (SFG) of 1064nm laser source to achieve UV light at 355nm.
Potassium Titanyle Arsenate (KTiOAsO4), or KTA crystal, is an excellent nonlinear optical crystal for Optical Parametric Oscillation (OPO) application. It has better non-linear optical and electro-optical coefficients, significantly reduced absorption in the 2.0-5.0 µm region, broad angular and temperature bandwidth, low dielectric constants.
Potassium Titanyl Phosphate (KTiOPO4 or KTP) KTP is the most commonly used material for frequency doubling of Nd:YAG and other Nd-doped lasers, particularly when the power density is at a low or medium level. To date, extra and intra-cavity frequency doubled Nd:lasers using KTP have become a preferred pumping source for visible dye lasers and tunable Ti:Sapphire lasers as well as their amplifiers. They are also useful green sources for many research and industry applications.
High values of laser damage threshold and conversion efficiency allow to use Mercury Thiogallate HgGa2S4 (HGS) non-linear crystals for frequency doubling and OPO/OPA in the wavelength range from 1.0 to 10 µm. It was established that SHG efficiency of CO2 laser radiation for 4 mm length HgGa2S4 element is about 10 % (pulse duration 30 ns, radiation power density 60 MW/cm2). The high conversion efficiency and wide range of radiation wavelength tuning allows to expect that this material may compete with AgGaS2, AgGaSe2, ZnGeP2 and GaSe crystals in spite of the considerable difficulty of big size crystals growth process.