Nonlinear optic (NLO) crystals are used for harmonic generation, including frequency doubling (SHG), tripling (3HG), frequency mixing; OPO(Optical Parametric Oscillator) and OPA(Optical Parametric Amplifier). Combining harmonic generation and frequency mixing, we can generate the 4th, 5th, or even 15th harmonics from the original laser output. Sanctity Laser supplies a verity of nonlinear optical crystals that cover a wide spectra range of nonlinear optical applications.