McGaugh M K, Verber C M, Kenan R P
Appl Opt. 1995 Mar 20;34(9):1562-8. doi: 10.1364/AO.34.001562.
The traditional design procedure for the waveguide Fresnel lens was carried over from those of bulk optics and micro-optics. In this design it is assumed that the lens thickness is negligibly small with respect to the focal length. This criterion does not hold for many integrated optic devices, in particular those with small mode-index modulations and long wavelengths. Under these conditions, the focal properties of the lens become unpredictable and the lens efficiency is reduced, both of which severely limit the usefulness of the lens as a waveguide-to-fiber coupler. To correct for this shortcoming, the standard Fresnel lens design procedure was modified to acocunt for the thickness of the lens explicitly. Both the standard and the modified Fresnel lens designs are outlined. A comparison of the limitations of the two lenses predicts better performance for the modified Fresnel lens. This is supported through computersimulation results for a pair of test lenses.
波导菲涅尔透镜的传统设计方法是从体光学和微光学的设计方法沿袭而来的。在这种设计中，假定透镜厚度相对于焦距可忽略不计。对于许多集成光学器件，尤其是那些具有小模式折射率调制和长波长的器件，该准则并不适用。在这些条件下，透镜的聚焦特性变得不可预测，并且透镜效率降低，这两者都严重限制了透镜作为波导 - 光纤耦合器的实用性。为了纠正这一缺点，对标准菲涅尔透镜设计方法进行了修改，以明确考虑透镜的厚度。文中概述了标准和改进的菲涅尔透镜设计。对两种透镜局限性的比较预测改进后的菲涅尔透镜性能更佳。一对测试透镜的计算机模拟结果证实了这一点。
