标题： 通过FIB铣削和CO$_2$激光烧蚀相结合制造定制化、低损耗光学谐振器 显示英文标题

标题： Fabrication of Customized, Low-Loss Optical Resonators by Combination of FIB-Milling and CO$_2$ Laser Ablation

摘要： 法布里-珀罗腔是精密计量、光机械和量子技术等应用中的重要工具。 主要挑战是创建微观球形镜结构，这些结构能够与高斯光束的波前精确匹配，同时提供高质量的表面。 我们提出了一种新的制造技术，通过结合聚焦离子束铣削（FIB）和CO$_2$激光平滑，能够在广泛的几何参数范围内制造定制的微观腔镜结构。 虽然FIB铣削使我们能够在镜片基板上以纳米级的分辨率刻印特征，但使用未聚焦的CO$_2$激光脉冲可以持续减少剩余表面变形，使其粗糙度降低到$\sigma_\text{RMS}=0.2\,$纳米。 轮廓偏离球形的平均偏差保持在几纳米以下。 该技术使得在包括光学纤维在内的广泛光学基板上，能够定制和重复制造低损耗光学元件。 因此，可以制造出具有预定义模式体积、高精细度和定制椭圆度的法布里-珀罗腔。 由于镜片的结构是由FIB铣削创建的，其逐像素的写入过程性质可用于创建由FIB铣削决定分辨率的任意结构。 同时，表面质量由CO$_2$激光平滑过程决定，而不会损害FIB铣削后的形状。 显示英文摘要

摘要： Fabry-Perot cavities are essential tools for applications like precision metrology, optomechanics and quantum technologies. A major challenge is the creation of microscopic spherical mirror structures which allow the precise matching with the wavefront of a Gaussian beam, while providing high surface quality. We present a novel fabrication technique, enabling the creation of customized microscopic cavity mirror structures over a wide range of geometrical parameters, by combining focused ion beam milling (FIB) and CO$_2$ laser smoothing. While FIB milling allows us to imprint features on the mirror substrate with a resolution on the nanometer scale, the application of defocused CO$_2$ laser pulses consistently reduces remaining surface deformations down to a roughness of $\sigma_\text{RMS}=0.2\,$nm. The average deviation of the profile from a spherical shape is kept below a few nanometres. This technique enables the customized and repeatable fabrication of low loss optics on a wide range of optical substrates, including optical fibres. Thus, Fabry-Perot cavities can be fabricated with pre-defined modal volume, high finesse and tailored ellipticity. Since the structural shape of the mirror is created by FIB milling, its pixel-by-pixel nature of the writing process can be used to create arbitrary structures with a resolution given by the FIB milling. At the same time, the surface quality is given by the CO$_2$ laser smoothing processes, without degrading the FIB milled shape.