The nonlinear optical crystal is the crystal that reveals the nonlinear optical effect more than two times for the laser electric field. Nonlinear optical crystal is a sort of functional material in which the frequency-doubling (or “frequency conversion”) crystal can be used to convert the laser wavelength, so regarding prolonging the tunable variety of the laser, which has important application value in the field of laser innovation.
There are numerous various sorts of nonlinear crystals, Common lithium niobate (LiNbO3–LN), lithium tantalate (LiTaO3–LT), potassium dihydrogen phosphate (KH2PO4–KDP), potassium deuterium 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 fluoroborate (KBe2BO3F2–KBBF), silver things (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 made use of in laser regularity doubling, sum regularity, difference regularity, optical parametric boosting, electro-optic modulation, electro-optic deflection, etc.
Nonlinear crystal
For nonlinear optical crystals, along with having huge efficient nonlinear coefficients, the following residential or commercial properties are additionally needed:
- 1. In general, the crystal needs to have high transparency for the wavelength included;
- 2, the interior absorption should be reduced, and the anti-damage limit must be high;
- 3. Stable physical as well as chemical residential properties, moderate firmness, no deliquescence;
- 4. Stable crystal top quality, plus size, sensible cost, simple layer.
Right here are some instances of usual nonlinear optical crystals
BBO nonlinear crystal
BBO crystal is identified as the most outstanding second-order nonlinear optical crystal in the world. One of its amazing characteristics is its broad frequency inflection range. More notably, by utilizing its frequency down-conversion process, BBO crystal can be made right into a continually tunable, fully healed tuned laser with a wavelength from noticeable to near-infrared.
Barium borate (BBO) has large birefringence, reduced diffusion, high damage limit, wide phase matching variety, good temperature stability, and a huge nonlinear optical effect. Also, the frequency doubling coefficient is six times that of the KDP crystal. It has a real variety of pervious to light, reduced absorption coefficient, the weaker the piezoelectric buzzing impact, relative to various other crystal electro-optic inflection, has higher extinction proportion, the bigger phase in a sustaining role, high optical damages limit, the temperature level of the broadband matching, and also excellent optical homogeneity and also to improve the laser result power security, Especially for the triple regularity Nd: YAG laser has a wide variety of applications.
LBO
Lithium trisborate, or LBO, is an outstanding high-power UV frequency-doubling crystal with a wide passage band, high damage threshold, and a big acceptance Angle. Lithium trisborate (LiB3O5, described as LBO) crystal is often used in the middle and high power 1064nm dual and triple frequency lasers. It has a high light damage resistance limit, excellent light harmony, wide obtaining Angle, great mechanical residential properties, solid thermal shock resistance, microduplication, and a huge nonlinear coefficient.
It is one of the nonlinear crystals with great, thorough homes. The greatest advantage of LBO is that it can use temperature level adjusting to attain non-critical phase matching (NCPM). When the regularity doubling process satisfies the non-critical phase matching relation, the departure Angle between the fundamental frequency and the second harmonic of the frequency increasing is 0. Right now, the reliable length of the LBO crystal can, in theory, reach infinity, which can compensate for its little nonlinear coefficient. Because of its big damage limit, this implies that high-power essential wave pumping can be accomplished.
MgO: LiNbO3.
Compared with LiNbO3 crystal, MgO: LiNbO3 crystal has special advantages in applying NCPM regularity doubling, blending, and optical parametric oscillation in ND-doped lasers.
The anti-damage limit of drugged MgO: LiNbO3 crystal is greater than two times higher than that of pure LiNbO3 crystal.
