| Type |
Characteristics |
Applications |
Lithium Niobate Crystal
(LiNbO3, LN Crystal) |
Strong nonlinearity, wide transparency range from 420 nm to 5.2 μm, and excellent nonlinear, electro - optic and piezoelectric properties |
Nonlinear frequency conversion for wavelengths > 1 μm and electro - optic modulators (EOM, 500nm-3um, with a relatively high bandwidth) It is an anisotropic crystal, and its polarization direction has a significant influence on the efficiency. Thermal drift effect will occur, and temperature control is required for high-precision applications. |
Lithium Tantalate Crystal
(LiTaO3, LT Crystal) |
High chemical stability, low dielectric loss, high detectivity figure - of - merit, and very good electro - optic, piezoelectric and pyroelectric properties |
Materials for pyroelectric infrared detectors, resonators, filters, transducers, etc. Also used in optical Windows (~250 nm - 5 µm); If it is used as an electro-optic modulator, the electro-optic coefficient is slightly worse than that of Lithium Niobate Crystal , but the damage threshold is higher and the temperature drift is smaller. |
Periodically Poled Lithium Niobate Crystal
(LiNbO3, PPLN Crystal) |
High nonlinear d - coefficient, no walk - off property, relatively low damage threshold |
Widely used in devices for nonlinear frequency conversion, biology, material analysis, femtosecond lasers, terahertz, etc. Its SHG conversion efficiency is very high. But high-precision temperature control is required. The price is relatively low. |
| Periodically Stoichiometric Lithium Tantalate Crystal (LiTaO3, PPSLT Crystal) |
High damage threshold, high nonlinear coefficient, high thermal conductivity, high photorefractive coefficient |
Suitable for visible light generation applications, especially high - power green light generation. But medium and high precision temperature control is required; The SHG conversion efficiency is better than that of PPKTP but slightly worse than that of PPLN. |
Potassium Titanyl Phosphate Crystal
(KTiOPO4, KTP Crystal) |
High nonlinearity, high mechanical stability, high optical quality, and transparency range from 350 nm to 4.5 μm |
Suitable for periodic polarization, medium and low power frequency doubling of neodymium-doped DPSS lasers, and nonlinear OPO media |
Periodically Poled Potassium Titanyl Phosphate Crystal
(KTiOPO4, PPKTP Crystal) |
Supports all nonlinear applications within the transparency range of KTP; no phase - matching limitations of KTP; effective nonlinear coefficient is three times that of KTP |
Frequency - doubling (SHG) devices at 1064 nm and 946 nm, OPO devices, etc. Its SHG conversion efficiency is very high, but slightly lower than that of PPLN. However, it has a very low temperature dependence and does not require temperature control. |
Potassium Dihydrogen Phosphate Crystal
(KH2PO4, KDP Crystal) |
Excellent ultraviolet transmittance, high laser damage threshold, relatively low nonlinearity, can grow in large size, high hygroscopicity |
Frequency multiplier for neodymium-doped DPSS lasers, triplers and quadruplers for neodymium - doped lasers; Q - switches for Ti:sapphire, emerald, neodymium - doped lasers |
Potassium Niobate Crystal
(KNbO3, KN Crystal) |
High nonlinearity(Similar to KTP), wide transparency range (0.4 - 5 mm), unaffected by photorefractive effect, and low damage threshold. |
Electro - optics and nonlinear optics, photorefractive applications of laser diodes, dynamic holography and optical phase - conjugate optical waveguides in near - infrared, optical second - harmonic generation (SHG), frequency doublers (Similar to KTP) |
Potassium Titanyl Arsenate Crystal
(KTiOAsO4, KTA Crystal) |
Good nonlinear optical and electro - optical properties(Similar to KTP), significantly reduced absorption in the wavelength range of 2.0 - 5.0 μm, wide angular and temperature bandwidth, low dielectric constant |
OPO for mid - infrared generation - up to 4 μm; sum - and difference - frequency generation in the mid - infrared range; electro - optical modulation and Q - switching |
Rubidium Titanyl Phosphate Crystal
(RbTiOPO4, RTP Crystal) |
Wide transparency range; stable mechanical and chemical properties; high damage threshold, high - temperature stability, low half - wave voltage, suitable for high - frequency operation, and fast response |
Electro - optical modulators, electro - optical Q - switches |
Lithium Triborate Crystal
(LiB3O5, LBO Crystal) |
Wide transmission band, good ultraviolet transmittance, slight deliquescence, good physical and chemical properties, moderate nonlinear optical coefficient, good optical uniformity, high damage threshold, large acceptance angle and small walk - off angle, low temperature dependence and no need for temperature control. |
High - power near - infrared second - harmonic generation, sum - frequency generation to produce visible ultraviolet lasers, and widely tunable optical parametric oscillators in the visible near - infrared range |
Cesium Lithium Borate Crystal
(CsLiB6O10, CLBO Crystal) |
Sufficiently large nonlinear coefficient, short absorption edge, large angular, spectral and temperature bandwidths and other nonlinear optical characteristics, as well as extremely high damage thresholds. |
Well - suited for second - order and higher - order harmonic generation. It is an excellent material for fabricating ultraviolet and deep - ultraviolet all - solid - state lasers. With a CLBO - frequency - quadrupled YAG laser, the 266nm ultraviolet light output has reached 42 watts, and the femtosecond laser from mid-infrared to UV |
Barium Metaborate Crystal
(β−BaB2O4, BBO Crystal) |
High nonlinear optical coefficient, low group velocity dispersion, broad transparency range (189 - 3500 nm) and high damage threshold, with the highest nonlinearity in the ultraviolet range |
Harmonic generation and frequency doubling of pulsed Yb - doped crystal lasers, third - harmonic generation of Ti:sapphire lasers, and widely tunable Type - I and Type - II OPOs |
Yttrium Calcium Oxoborate Crystal
(YCa4O(BO3)3, YCOB Crystal) |
The nonlinear optical coefficient is equivalent to that of BBO crystal and LBO crystal. The second - and third - order effective frequency - doubling coefficients reach 2.8 and 1.4 times that of KDP respectively. It has a large aperture, high damage strength in the femtosecond region, stable physical and chemical properties, and good processing performance. |
Ultraviolet - band optical frequency doubler |
Zinc Germanium Phosphide Crystal
(ZnGeP2, ZGP Crystal) |
It has the largest nonlinear coefficient among infrared crystals. The effective transmission range is from 2 μm to 12 μm. It has a relatively high damage threshold. The nominal absorption coefficient of the o - wave at ~2.1 μm is < 0.04 cm⁻¹. |
Harmonic generation of the fundamental waves of CO₂ and CO lasers; Generation of continuously tunable radiation in the MWIR and LWIR ranges through OPO and DFG technologies; Generation of frequencies in the terahertz range |
Silver Gallium Selenide Crystal
(AgGaSe2, AGSe Crystal) |
It shows excellent performance within the transmission range of 0.73 to 18 μm. It has low light absorption and scattering, and a high FOM (Figure of Merit). It is used for nonlinear interactions in NIR and MIR. |
Frequency mixing in the infrared region from 4.0 to 18.3 μm; Second - harmonic generation and up - conversion of CO₂ lasers; Tunable OPO for solid - state lasers with an efficiency of up to 10% |
Silver Gallium Sulfide Crystal
(AgGaS2, AGS Crystal) |
Has unique nonlinear characteristics within the transmission range of 0.5 to 12 μm; low light absorption and scattering; short - wavelength transparency |
The mixing range in the intermediate IR region is 4.0 to 18.3 μm; second - harmonic generation and up - conversion of CO₂ lasers; suitable for tunable OPO of solid - state lasers |
Gallium Selenide Crystal
(GaSe, GaSe Crystal) |
Extremely soft, unable to be polished or coated; transparency range of 900 - 16000 nm; can only be cut along (001); due to high refractive index and directional limitations, can only use a small Theta angle; a cheaper alternative to AGS or AGSe |
High - power femtosecond lasers; terahertz (THz) generation(Terahertz window sheet); an alternative solution for generating broadband mid - infrared (MIR) electromagnetic waves; for CO, CO₂ and other lasers, second - harmonic generation (SHG) in the mid - infrared (MIR); optical parametric generation (OPG) within 3 - 16 μm |
Cadmium Selenide Crystal
(CdSe, CdSe Crystal) |
Low light absorption; broadband specific transmission range: 2.5 μm to 16 μm |
Far - infrared wavelength radiation generated by DFG and OPO schemes; materials for infrared optical elements: substrates, polarizers, wave plates, etc. |