Nonlinear optics refers to higher order optical effects in materials where the polarization responds nonlinearly to the electric field of light passing through the material. Nonlinear crystals are often used for the generation of higher order harmonics from a high intensity fundamental input. Applications of nonlinear crystals include frequency doubling (SHG), third harmonic generation (THG), and use in optical parametric oscillators (OPO) and optical parametric amplifiers (OPA).

Beta Barium Borate (BBO)

Beta-Barium Borate (β-BaB2O4 or BBO) is a nonlinear optical crystal with broad spectral transparency, large nonlinear coefficient and wide phase matching range. These factors combined with a high damage threshold make BBO a popular choice for a wide range of nonlinear optical applications.

Potassium Titanyl Phosphate (KTiOPO4 or KTP)

Potassium Titanium Oxide Phosphate (KTiOPO4 or KTP) is the nonlinear crystal of choice for efficiently frequency doubling of near infrared (1064 nm) laser light into the visible green (532 nm). Large nonlinear coefficients int his range allow KTP to reach conversion efficiencies as high as 80%. KTP is used for second harmonic generation at a wide range of powers from high intensity Q-switched lasers to green laser pointers.