Opt Lett. 2013 Nov 15;38(22):4785-8. doi: 10.1364/OL.38.004785.
The fundamental quasi-TE and quasi-TM modes of a sub-wavelength strip silicon waveguide are not purely TE or TM as the plane waves in free space. We investigate theoretically and experimentally the far-field polarization compositions of the two waveguide modes after they emanate from the waveguide facet. The measured polarization extinction ratios (PERs) of 31 dB for the quasi-TM mode and 26 dB for quasi-TE mode using free-space polarizers are consistent with our numerical analysis. Moreover, our far-field simulations show that the free-space measurement of PERs is influenced, and in many cases limited, by the sizes of various apertures in the experimental setup. This suggests a potential trade-off between achievable PERs and overall power detection/collection efficiency.
亚波长条形硅波导的基本准 TE 和准 TM 模式与自由空间中的平面波不同，不是纯粹的 TE 或 TM 模式。我们从理论和实验上研究了这两种波导模式从波导端面出射后的远场偏振组成。使用自由空间偏振器测量的准 TM 模式的偏振消光比 (PER) 为 31dB，准 TE 模式的 PER 为 26dB，与我们的数值分析一致。此外，我们的远场模拟表明，PER 的自由空间测量受到实验装置中各种孔径大小的影响，在许多情况下受到限制。这表明在可实现的 PER 和整体功率检测/收集效率之间存在潜在的权衡。
