Filipkowski Adam, Piechal Bernard, Pysz Dariusz, Stepien Ryszard, Waddie Andrew, Taghizadeh Mohammad R, Buczynski Ryszard
Opt Lett. 2015 Nov 15;40(22):5200-3. doi: 10.1364/OL.40.005200.
We report the design and fabrication of nanostructured gradient index microaxicons suitable for integration with optical fibers. A structure with the effective refractive index decreasing linearly from the center to the edges (i.e., an axicon) was designed using a combination of a simulated annealing method and the effective medium theory. The design was verified numerically with beam propagation method simulations. The axicons were made by the modified stack and draw method and integrated with optical fibers. The optical properties of the fabricated elements were measured and showed good agreement with the numerical simulations. The fabricated axicons produced an extended line focus at a distance from about 70 to 160 μm from the lens facet with a minimum FWHM diameter of 8 μm at 90 μm. At smaller distances, an interference pattern is observed both in the experiment and in simulations, which is attributed to the uneven effective refractive index profile at the structure.
我们报告了适用于与光纤集成的纳米结构梯度折射率微轴锥镜的设计与制造。利用模拟退火方法和有效介质理论相结合的方式，设计出了一种有效折射率从中心到边缘呈线性递减的结构（即轴锥镜）。通过光束传播法模拟对该设计进行了数值验证。轴锥镜采用改进的堆叠拉制法制造，并与光纤集成。对所制备元件的光学特性进行了测量，结果与数值模拟结果吻合良好。所制备的轴锥镜在距透镜表面约70至160μm的距离处产生了一个扩展线聚焦，在90μm处的最小半高宽直径为8μm。在较小距离处，实验和模拟中均观察到干涉图样，这归因于结构处有效折射率分布不均匀。
