Barona-Ruiz Miguel, Pérez-Armenta Carlos, Ortega-Moñux Alejandro, Wangüemert-Pérez Gonzalo, Molina-Fernández Íñigo, Cheben Pavel, Halir Robert
Opt Express. 2022 Oct 10;30(21):38930-38937. doi: 10.1364/OE.467908.
Photonic systems built on the Silicon-on-Insulator platform exhibit a strong birefringence, and must thus be operated with a single polarization for most applications. Hence, on-chip polarizers that can effectively suppress an undesired polarization state are key components for these systems. Polarizers that extinguish TE polarized light while letting TM polarized light pass with low losses are particularly challenging to design for the standard 220 nm Silicon-on-Insulator platform, because the modal confinement is stronger for TE polarization than for TM polarzation. Here, we propose and design a broadband, low loss and high extinction ratio TM-pass polarizer by engineering a Bragg grating that reflects the fundamental TE mode into the first order TE mode using a subwavelength metamaterial which at the same time allows the TM mode to pass. Our device achieves an extinction ratio in excess of 20 dB, insertion losses below 0.5 dB and back-reflections of the fundamental TE mode of the order of -20 dB in a bandwidth of 150 nm as demonstrated with full 3D-FDTD simulations.
基于绝缘体上硅平台构建的光子系统表现出很强的双折射，因此对于大多数应用而言，必须以单一偏振态运行。因此，能够有效抑制不需要的偏振态的片上偏振器是这些系统的关键组件。对于标准的220纳米绝缘体上硅平台来说，设计能熄灭TE偏振光同时让TM偏振光低损耗通过的偏振器极具挑战性，因为TE偏振的模式限制比TM偏振更强。在此，我们通过设计一种布拉格光栅来提出并设计一种宽带、低损耗且高消光比的TM通偏振器，该光栅利用亚波长超材料将基模TE模式反射为一阶TE模式，同时允许TM模式通过。如全3D有限时域差分法模拟所示，我们的器件在150纳米带宽内实现了超过20分贝的消光比、低于0.5分贝的插入损耗以及基模TE模式约为 -20分贝的背反射。
