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化工原料常见问题

偏硼酸钡α-BBO与β- BBO的区别及应用总结

频道:化工原料常见问题 日期: 浏览:105

偏硼酸钡(BaB2O4)存在着高温相(α-BBO)和低温相(β- BBO)两种多型体,熔点为1095℃,其相变温度为925℃左右。


一、α-BBO


    高温相α-BBO晶体属三方晶系,单胞参数为:a=b=0.7235nm,c=3.9192 nm。高温相α-BBO晶体为负光轴晶体,具有大的双折射率,透光范围为189~3500nm,尤其在紫外区的透过率很高(95%),而且物理化学性能稳定,机械加工性能优异。具有中心对称结构,α-BBO晶体无二阶非线性效应。


    广泛应用于光偏转技术、高功率激光和超快激光应用等领域。主要用于制作紫外偏振棱镜如格兰泰勒棱镜、渥拉斯顿棱镜、高功率光隔离器以及超快激光的群速失配补偿器等。


High temperature phase BBO (alpha-BBO, a-BBO) is a negative uniaxial crystal with a large birefringence over the broad transparent range from 189 nm to 3500 nm. The physical, chemical, thermal, and optical properties of alpha-BBO crystal are similar to those of the low temperature phase beta-BBO crystal. However, there is no second order nonlinear effect in alpha-BBO crystal due to the centrosymmetry in its crystal structure and thus it has no use for second order nonlinear optical processes. Instead, alpha-BBO is widely used for fabrication of polarizers, polarizing beam displacers, phase retarders, birefringent plates, and time delay compensators especially those for UV and high power lasers.


二、β- BBO


  低温相β-BBO晶体也属三方晶系,单胞参数为:a=b=12.532A,c=12.717A,Z=7。可实现相位匹配的波段范围宽(409.6—3500nm),可透过波段范围宽(190—3500nm),倍频转换效率高(相当于KDP晶体的6倍),光学均匀性好,高损伤阈值(100ps脉宽的1064nm10GW/cm^2),温度接收角宽(55℃左右)。


      低温相β-BBO晶体在非线性光学上面应用广泛,在Nd:YAG激光二、三、四倍频上的性能优异,是213nm光五倍频的最佳选择。二倍频的转换效率大于70%,三倍频60%,四倍频50%。具有较小的接受角和较大的走离角,因此获得理想的转换效率的关键是使用较好质量的基频光(具有小的发散角,较好的模式条件等)。


BBO Crystal is one of the essential nonlinear optical crystals. Beta-barium borate (β-BaB2O4,β-BBO) combines many outstanding features such as its high nonlinear optical coefficients and low group-velocity dispersion, broad transparency range (189–3500 nm) high damage threshold. This unique combination ensures that β-BBO crystal is a promising candidate for nonlinear optical applications such as frequency converters and optical parametric oscillators. In quantum optics, β-BBO crystal can generate entangled photon pairs and ten-photon entanglement.


BBO nonlinear crystal is a negative uniaxial crystal. It provides phase matching for various second-order interactions almost over its entire transparency range. This transparency ranges from 185 nm to 3.3 µm, as inferred from transmittance measurements using crystal samples of a few mm thickness. It is widely used for nonlinear frequency conversion in the ultraviolet, visible, and near-infrared. The BBO crystal is the most critical nonlinear crystal for near-infrared optical parametric chirped-pulse amplifiers, which currently deliver few optical cycle pulses with high average and ultrahigh peak powers.

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