Luque-González José Manuel, Herrero-Bermello Alaine, Ortega-Moñux Alejandro, Sánchez-Rodríguez Marina, Velasco Aitor V, Schmid Jens H, Cheben Pavel, Molina-Fernández Íñigo, Halir Robert
Opt Lett. 2020 Jul 1;45(13):3398-3401. doi: 10.1364/OL.394696.
On-chip polarization splitters are key elements for coherent optical communication systems and polarization diversity circuits. These devices are often implemented with directional couplers that are symmetric for one polarization and strongly asymmetric for the other polarization. To achieve this asymmetry, highly dissimilar waveguides are used in each coupler arm, often requiring additional material layers or etch steps. Here we demonstrate polarization splitting with a directional coupler composed of two fully etched subwavelength waveguides, differing only in the tilt angle of the silicon segments. Our device exhibits deep-UV compatible feature sizes, is 14 µm long, and covers a 72 nm bandwidth with insertion losses below 1 dB and an extinction ratio in excess of 15 dB.
片上偏振分束器是相干光通信系统和偏振分集电路的关键元件。这些器件通常由定向耦合器实现，该定向耦合器对一种偏振是对称的，而对另一种偏振是高度不对称的。为了实现这种不对称性，在每个耦合器臂中使用了非常不同的波导，这通常需要额外的材料层或蚀刻步骤。在这里，我们展示了一种由两个完全蚀刻的亚波长波导组成的定向耦合器的偏振分束，这两个波导仅在硅段的倾斜角度上有所不同。我们的器件具有与深紫外兼容的特征尺寸，长度为14 µm，覆盖72 nm带宽，插入损耗低于1 dB，消光比超过15 dB。
