Benedikovic Daniel, Alonso-Ramos Carlos, Pérez-Galacho Diego, Guerber Sylvain, Vakarin Vladyslav, Marcaud Guillaume, Le Roux Xavier, Cassan Eric, Marris-Morini Delphine, Cheben Pavel, Boeuf Frédéric, Baudot Charles, Vivien Laurent
Opt Lett. 2017 Sep 1;42(17):3439-3442. doi: 10.1364/OL.42.003439.
Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy. In this Letter, we demonstrate for the first time, to the best of our knowledge, the realization of an ultra-directional L-shaped grating coupler, seamlessly fabricated by using 193 nm deep-ultraviolet (deep-UV) lithography. We also include a subwavelength index engineered waveguide-to-grating transition that provides an eight-fold reduction of the grating reflectivity, down to 1% (-20 dB). A measured coupling efficiency of -2.7 dB (54%) is achieved, with a bandwidth of 62 nm. These results open promising prospects for the implementation of efficient, robust, and cost-effective coupling interfaces for sub-micrometric SOI waveguides, as desired for large-volume applications in silicon photonics.
光栅耦合器能够通过光纤实现与硅芯片的位置友好型接口连接。传统的耦合器设计需要相对复杂的架构，以便为亚微米绝缘体上硅（SOI）波导提供高效的光耦合。相反，双蚀刻光栅中的闪耀效应在降低制造复杂性的同时提供了高耦合效率。在本信函中，据我们所知，我们首次展示了通过使用193纳米深紫外（深紫外）光刻无缝制造的超定向L形光栅耦合器。我们还包括一个亚波长折射率工程化的波导到光栅的过渡结构，该结构可将光栅反射率降低八倍，降至1%（-20 dB）。实现了-2.7 dB（54%）的测量耦合效率，带宽为62纳米。这些结果为实现用于亚微米SOI波导的高效、稳健且经济高效的耦合接口开辟了广阔前景，这是硅光子学中大规模应用所期望的。
