Barium borate is an inorganic compound with the chemical formula BaB2O4. It can be a hydrate, a dehydrated type, a white powder, or a colorless crystal. There are 2 kinds of the high-temperature stage (α-BBO) and low-temperature phase (β-BBO), and the stage transition temperature level is 925 ℃.
α-BBO
β-BBO crystal development has been studied for more than 20 years. It has come to be a commonly used nonlinear optical product. In contrast, α-BBO has been less researched. α-BBO is a suitable UV birefringent crystal with center symmetry and non-linear impact. Yet, it has an excellent birefringence index, specifically in the ultraviolet band, with a high transmission ratio (95%), transmittance series of 189nm ~ 35000nm, stable physical and chemical residential or commercial properties, and excellent mechanical properties.
Application
α-BBO crystals have superb optical properties such as a huge refractive index and wide passage range. They are widely used in optical deflection innovation, high-power, and ultrafast laser applications. It is primarily utilized to make ultraviolet polarization prisms such as the Grantler prism, Wollaston prism, high-power optical isolator, and team speed mismatch compensator of the ultrafast laser.
β-BBO
BBO is a common nonlinear optical crystal. A nonlinear optical crystal is a crystalline material that utilizes the nonlinear action of light wave polarization when it goes through the medium to react with the light wave, leading to harmonic generation (nonlinear impact) at the sum regularity, distinction frequency, and so forth. BBO crystal is acknowledged as one of the planet’s exceptional 2nd-order nonlinear optical crystals.
Nonlinear property
Nonlinear optical crystals reveal greater than quadratic nonlinear optical effects to laser intense electrical field. It is a functional product in which frequency increasing (or “regularity conversion”) crystal can be used to transform laser wavelength to expand the tunable range of laser, which has actual application worth in the modern laser technology field.
Application
1) Used in 1064nm Nd: YAG laser with a double, three-way, quadruple, and quad regularity.
2) Utilized for color laser and also titanium treasure laser of double frequency, three-way frequency, amount regularity, distinction regularity, etc
3) Optical Parametric Amplifier (OPA) and Optical Parametric Oscillator (OPO).
Optical parametric boosting and oscillation describe the nonlinear optical effects of multiwave blending.
Electro-optical properties
In addition to the remarkable nonlinear effect, one more popular optical building of BBO is the electro-optical impact.
The electro-optic impact is a basic term for the adjustments of optical residential properties of objects under the action of applied electric area. Usually, this applied electric area changes gradually with time compared to the regularity of light. These various electro-optical impacts come under two classifications:
Changes in light absorption.
Electroabsorption effect: Variant of light absorption constant in general feeling.
Franz-caldisi result: Adjustment in light absorption of certain huge semiconductors under a used electric area.
Quantum arrest Stark effect: Variation of light absorption in particular semiconductor quantum Wells under an applied electrical field.
Electric color result: The absorption of a particular wavelength by an applied electric field, leading to an adjustment in the color of an object.
Adjustments in refractive index and dielectric constant.
Pockers effect (additionally called straight electro-optic impact): The modification of the crystal’s refractive index caused by an applied electric field is symmetrical to the strength of the electrical area. Only those crystals without inversion balance can produce the Pockers result.
Kerr effect (also referred to as a second-order nonlinear electro-optical result): The adjustment of the refractive index of the crystal triggered by an applied electric field is symmetrical to the square of the electrical area strength. Any crystal can produce the Kerr impact, yet the impact’s toughness is much less than that of the Pockers effect.
Application
BBO Electro-optic Q-Switch (Pockels cell).
Compared to standard KD * P electro-optic regulated crystal, BBO( Barium metabate β-BaB2O4) crystal has a low absorption coefficient. There are additionally weak piezoelectric ringing effects, wider range transmission arrays (210-2000nm), and various other benefits. Compared to RTP electro-optic regulated crystal, BBO crystal has greater termination proportion, anti-damage limit, and temperature adaptability, which is conducive to enhancing the security of laser output power. Consequently, the electro-optical Q switch made from BBO crystal is frequently used in the electro-optical Q-switched solid-state laser with high rep regularity (1MHz) as well as high power (approximately 1000W), dental caries inversion cool Q laser as well as all-solid picosecond as well as femtosecond regrowth amplification laser system.
BBO electro-optical Q switch can be turned off and withstand up to 150W of oscillating optical power in dental caries (laser outcome power up to 50W) without water air conditioning. The drawbacks of BBO crystals are a small electro-optic coefficient and fairly high half-wave voltage, so the half-wave voltage and quarter-wave voltage can be lowered by increasing the crystal’s length and using two BBO crystals in the collection.
Precautions.
As a result of the reduced reliability of BBO, the surface of polished BBO crystals is quickly obscured by wet air. So after the polishing process, a thin movie finish is related to the surface. The safety coating (P layer) or anti-reflective coating (AR finish) protects the crystal surface area from wetness somewhat. However, even small pollutants (dust fragments, stress, fingerprints, etc.) can affect BBO crystals’ efficiency, i.e., transmission or reflection. On top of that, BBO crystals are easily harmed if impurities come into direct contact with laser radiation.
