Lithium triborate (LBO or _LiB3O5) is a well-known nonlinear crystal with a wide transmission range from VUV to IR. Its high damage threshold as well as its chemical and mechanical properties make it ideal for nonlinear applications. It is therefore often used to double the frequency of Nd:YAG lasers. The large band gap makes it resistant to UV radiation.

The LBO crystals can be used for frequency doubling (SHG) and tripling (THG) of pulsed Nd:YAG lasers, Ti:sapphire lasers and dye lasers, whereby high pulse energies are also permitted. Another application is the frequency conversion of Cw and quasi-Cw radiation by non-critical phase matching (NCPM). An optical parametric oscillator (OPO) with type I or type II phase matching can be constructed. These crystals are also suitable for OPCPA (optical parametric chirped-pulse amplification).