Gorelick Sergey, de Marco Alex
Opt Express. 2018 Nov 26;26(24):32324-32331. doi: 10.1364/OE.26.032324.
The high refractive index of lithium niobate crystal (n = 2.2) and the highly transparent range (300-5000 nm), makes it a perfect material for refractive lenses and other types of micro-optical elements. This material already finds extensive use in waveguides and photonic crystals, however, little work has been done on producing refractive optical components in lithium niobate, presumably due to the challenges associated with its fragility and difficulties in three-dimensional micromachining. In this study, we fabricated high-quality refractive micro-lenses and micro-axicons with low surface roughness (< λ / 20), with 220 µm diameters and sag heights up to 22 µm in single-crystal LN using focused Xe beam milling. Xe ion beam milling is a flexible and rapid technique allowing realization of complex three-dimensional surface reliefs directly in lithium niobate. We characterized the optical performance of the fabricated elements showing sub-µm focusing capabilities of both the lenses and axicons.
铌酸锂晶体的高折射率（n = 2.2）和高透明范围（300 - 5000 nm），使其成为用于折射透镜和其他类型微光学元件的理想材料。这种材料已在波导和光子晶体中得到广泛应用，然而，在铌酸锂中制造折射光学元件的工作却很少，这大概是由于其易碎性以及三维微加工困难所致。在本研究中，我们使用聚焦氙束铣削在单晶铌酸锂中制造出了具有低表面粗糙度（<λ / 20）、直径为220 µm且矢高可达22 µm的高质量折射微透镜和微轴棱锥。氙离子束铣削是一种灵活且快速的技术，能够直接在铌酸锂中实现复杂的三维表面形貌。我们对所制造元件的光学性能进行了表征，结果表明透镜和轴棱锥均具有亚微米级的聚焦能力。
