Zhou Guangyong, Jesacher Alexander, Booth Martin, Wilson Tony, Ródenas Airán, Jaque Daniel, Gu Min
Centre for Micro-Photonics and CUDOS, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia.
Opt Express. 2009 Sep 28;17(20):17970-5. doi: 10.1364/OE.17.017970.
We report on the experimental observation of "focus splitting" when light is tightly focused into a uniaxial lithium niobate crystal along its optical axis. This effect consists in the focal spot being split into two major sub-peaks along the axial direction. For the microfabrication applications such as three-dimensional photonic crystal fabrication and waveguide writing, this effect is highly undesired since it can lead to the generation of multiple distinct voxels in the vicinity of the focus. The splitting is caused by different birefringence induced aberrations for the ordinary and extraordinary polarization eigenmodes. We present numerical simulations which support our observations and suggest methods to avoid this effect.
我们报告了将光沿单轴铌酸锂晶体的光轴紧密聚焦时“焦点分裂”的实验观察结果。这种效应表现为焦点光斑沿轴向分裂成两个主要子峰。对于诸如三维光子晶体制造和波导写入等微加工应用，这种效应是非常不利的，因为它会在焦点附近导致产生多个不同的体素。这种分裂是由寻常和非寻常偏振本征模的不同双折射诱导像差引起的。我们给出了支持我们观察结果的数值模拟，并提出了避免这种效应的方法。
