Nonlinear optical crystal
The nonlinear optical crystal is the crystal which reveals the nonlinear optical effect greater than two times for the laser electrical area. 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 as to prolong the tunable series of the laser, which has important application value in the field of laser modern technology.
There are thousands of various sort 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 commonly used in laser regularity doubling, sum frequency, distinction regularity, optical parametric boosting, electro-optic inflection, electro-optic deflection, etc.
Fundamental properties of nonlinear crystals
For nonlinear optical crystals, along with having huge efficient nonlinear coefficients, the complying with buildings are additionally required:
- As a whole, the crystal must have high transparency for the wavelength involved;
- The interior absorption ought to be reduced, the anti-damage limit should be high;
- Stable physical and chemical properties, modest firmness, no deliquescence;
- Secure crystal top quality, plus size, sensible cost, very easy finish.
Some nonlinear crystal crystals
Below are some instances of common nonlinear optical crystals.
BBO
BBO nonlinear crystal is recognized as one of the most excellent second-order nonlinear optical crystal in the world. One of its impressive attributes is its wide frequency inflection range. Extra importantly, by utilizing its frequency down-conversion process, BBO crystal can be made into a constantly tunable completely cured tuned laser with wavelength from noticeable to near-infrared.
Barium borate (BBO) has large birefringence and reduced diffusion, high damage limit, wide phase matching array, excellent temperature stability, huge nonlinear optical impact, as well as the frequency doubling coefficient is 6 times that of KDP crystal. It has an extremely vast array of pervious to light, reduced absorption coefficient, the weaker the piezoelectric ringing result, relative to various other crystal electro-optic inflection, has greater extinction ratio, the bigger stage in a sustaining function, high optical damages threshold, the temperature of the broadband matching, and also superb optical homogeneity and to improve the laser result power stability, Especially for the three-way regularity Nd: YAG laser has a large range of applications.
LBO
Lithium trisborate, additionally referred to as LBO crystal, is an excellent high-power UV frequency-doubling crystal with large transmittance band, high damages threshold and big approval Angle. Lithium trisborate (LiB3O5, described as LBO) crystal is often used in center and high power 1064nm dual as well as three-way frequency lasers. It has really high light damage resistance limit, great light uniformity, broad receiving Angle, great mechanical buildings, solid thermal shock resistance, microdelixation, and also big nonlinear coefficient. It is among the nonlinear crystals with excellent thorough residential properties.
The largest advantage of LBO is that it can make use of temperature level adjusting to achieve non-critical phase matching (NCPM). When the regularity doubling procedure satisfies the non-critical phase matching connection, the departure Angle between the fundamental frequency and the 2nd harmonic of the regularity doubling is 0. Right now, the efficient size of the LBO crystal can theoretically reach infinity, which can compensate for its small nonlinear coefficient. Due to its huge damages threshold, this indicates that high-power basic wave pumping can be attained.
MgO: LiNbO3
Compared to LiNbO3 crystal, MgO: LiNbO3 crystal has its distinct advantages in the application of NCPM frequency doubling, blending as well as optical parametric oscillation in ND-doped lasers.
The anti-damage threshold of drugged MgO: LiNbO3 crystal is greater than two times greater than that of pure LiNbO3 crystal.
Read more: Faraday device
