The nonlinear optical crystal is the crystal which shows the nonlinear optical effect more than two times for the laser electric field. Nonlinear optical crystal is a kind of functional product, in which the frequency-doubling (or “regularity conversion”) crystal can be utilized to convert the laser wavelength, so regarding prolong the tunable series of the laser, which has essential application value in the field of laser modern technology.
There are thousands of various types 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 tris borate (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 extensively utilized in laser frequency doubling, sum regularity, difference regularity, optical parametric amplification, electro-optic inflection, electro-optic deflection, and so on.
Nonlinear crystal properties
For nonlinear optical crystals, in addition to having large effective nonlinear coefficients, complying with residential properties is additionally called for:
1, Generally, the crystal must have high transparency for the wavelength included;
2, the inner absorption needs to be reduced, and the anti-damage threshold must be high;
3, Steady physical and chemical homes, moderate solidity, no deliquescence;
4, Secure crystal quality, large size, reasonable rate, and easy coating.
Below are some examples of usual nonlinear optical crystals
BBO nonlinear optical crystal
BBO crystal is identified as the most outstanding second-order nonlinear optical crystal worldwide. Among its remarkable characteristics is its wide frequency inflexion variety. A lot more importantly, by using its frequency down-conversion process, BBO crystal can be made into a constantly tunable completely cured tuned laser with a wavelength from visible to near-infrared.
Barium borate (BBO) has big birefringence as well as reduced dispersion, high damage limit, broad phase-matching range, great temperature security, big nonlinear optical impact, and also the regularity doubling coefficient is 6 times that of KDP crystal. It has a very large range of pervious to light, low absorption coefficient, the weaker the piezoelectric ringing effect, relative to various other crystal electro-optic modulations, has greater extinction proportion, the larger phase in a sustaining function, high optical damage threshold, the temperature level of the broadband matching, as well as excellent optical homogeneity and to boost the laser outcome power stability, Especially for the triple regularity Nd: YAG laser has a wide range of applications.
LBO nonlinear optical crystal
Lithium tris borate, likewise called LBO, is a superb high-power UV frequency-doubling crystal with a broad passage band, high damage limit and big acceptance Angle. Lithium tris borate (LiB3O5, described as LBO) crystal is usually utilized in the centre as well as high power 1064nm dual and also three-way regularity lasers. It has a very high light damage resistance limit, excellent light harmony, wide obtaining Angle, good mechanical buildings, solid thermal shock resistance, microduplication, and also a large nonlinear coefficient.
It is one of the nonlinear crystals with outstanding detailed residential properties. The most significant advantage of LBO is that it can utilize temperature adjusting to attain non-critical stage matching (NCPM). When the regularity doubling process satisfies the non-critical phase matching connection, the departure Angle between the fundamental frequency, as well as the second harmonic of the frequency increase, is 0. At this time, the reliable size of the LBO crystal can in theory get to infinity, which can compensate for its small nonlinear coefficient. As a result of its large damage threshold, this means that high-power fundamental wave pumping can be attained.
MgO: LiNbO3 nonlinear optical crystal
Compared to LiNbO3 crystal, MgO: LiNbO3 crystal has special benefits in the application of NCPM frequency increasing, mixing and also optical parametric oscillation in Nd-doped lasers.
The anti-damage threshold of drugged MgO: LiNbO3 crystal is greater than two times more than that of pure LiNbO3 crystal.