Nonlinear optical crystals are crystals that exhibit secondary or higher nonlinear optical effects in response to strong laser electric fields.  Nonlinear optical crystal is a functional material, in which the frequency doubling (or “frequency conversion”) crystal can be used to convert the laser wavelength, thereby expanding the tunable range of the laser, which has important application value in the field of laser technology.NLO Crystals (Non-linear Optical Crystals) are used for extending the laser spectrum from deep UV to some distance IR with the aid of various harmonic generations (SHG, THG), sum frequency generations (SFG), difference frequency generations (DFG) and optical parametric oscillators (OPO).often Used Nonlinear Crystals，ATT offers NLO crystals consist of BBO, KTP, LBO, KD*P(DKDP), KTA, LiNbO3, AgGaS2, KDP, ADP, LiIO3, KNbO3, CLBO, KBBF, BiBO AgGaSe2, and so forth.