The nonlinear optical crystal is the crystal which reveals the nonlinear optical effect greater than twice for the laser electric field. Nonlinear optical crystal is a sort of practical product, in which the frequency-doubling (or “frequency conversion”) crystal can be made use of to transform the laser wavelength, so regarding prolong the tunable series of the laser, which has important application value in the field of laser modern technology.
There are hundreds of various kinds of nonlinear crystals, Common lithium niobate (LiNbO3– LN), lithium tantalate (LiTaO3– LT), potassium dihydrogen phosphate (KH2PO4– KDP), potassium dideuterium phosphate (KD2PO4– DKDP), lithium iodate (LiIO3– LI), potassium titanium phosphate (KTiOPO4– KTP), barium metaborate (BaB2O4– BBO), lithium trisborate (LiB3O5– LBO), potassium niobate (KNbO3– KN), cesium borate (CSB3O5– CBO), cesium lithium borate (LiCSB6O10– CLBO), potassium beryllium fluorborate (KBe2BO3F2– KBBF), silver thiogas (AgGaS2– AGS), silver selenium gallium (AgGaSe2– AGSe, arsenic-cadmium germanium (CDGEAS-CGA), cadmium selenide CdSe, Gallium selenide GaSe, phospho-germanium zinc (ZnGEP2-ZGP) are widely utilized in laser frequency increasing, amount frequency, distinction frequency, optical parametric amplification, electro-optic modulation, electro-optic deflection, etc.
Nonlinear crystal properties
For nonlinear optical crystals, in addition to having big efficient nonlinear coefficients, the adhering to homes are also needed:
- Generally, the crystal needs to have high transparency for the wavelength entailed;
- The interior absorption should be reduced, the anti-damage threshold must be high;
- Stable physical as well as chemical buildings, modest hardness, no deliquescence;
- Secure crystal high quality, large size, sensible price, easy covering.
- Here are some instances of typical nonlinear optical crystals
BBO nonlinear optical crystal
BBO crystal is recognized as the most outstanding second-order nonlinear optical crystal in the world. Among its remarkable qualities is its large regularity modulation array. Much more significantly, by utilizing its regularity down-conversion procedure, BBO crystal can be made right into a constantly tunable completely treated tuned laser with wavelength from noticeable to near-infrared.
Barium borate (BBO) has large birefringence and low diffusion, high damages limit, large phase matching range, excellent temperature security, big nonlinear optical impact, and the frequency increasing coefficient is six times that of KDP crystal. It has a very wide variety of pervious to light, low absorption coefficient, the weak the piezoelectric ringing effect, relative to various other crystal electro-optic inflection, has higher extinction proportion, the larger stage in a sustaining function, high optical damage limit, the temperature of the broadband matching, and also superb optical homogeneity and also to boost the laser outcome power security, Especially for the triple frequency Nd: YAG laser has a large range of applications.
LBO nonlinear optical crystal
Lithium trisborate, likewise known as LBO, is a superb high-power UV frequency-doubling crystal with large transmittance band, high damage limit and also large approval Angle. Lithium trisborate (LiB3O5, described as LBO) crystal is frequently made use of in middle and high power 1064nm double and three-way regularity lasers. It has really high light damage resistance threshold, excellent light uniformity, large getting Angle, excellent mechanical properties, strong thermal shock resistance, microdelixation, and also huge nonlinear coefficient. It is just one of the nonlinear crystals with exceptional extensive residential or commercial properties.
The largest advantage of LBO is that it can utilize temperature level adjusting to achieve non-critical stage matching (NCPM). When the regularity doubling procedure pleases the non-critical stage matching relation, the departure Angle in between the essential frequency and the 2nd harmonic of the frequency increasing is 0. Currently, the efficient length of the LBO crystal can theoretically reach infinity, which can compensate for its small nonlinear coefficient. As a result of its huge damage threshold, this implies that high-power basic wave pumping can be accomplished.
MgO: LiNbO3 crystal
Compared to LiNbO3 crystal, MgO: LiNbO3 crystal has its distinct benefits in the application of NCPM frequency increasing, blending as well as optical parametric oscillation in ND-doped lasers.
The anti-damage limit of drugged MgO: LiNbO3 crystal is greater than two times greater than that of pure LiNbO3 crystal.
