Xiao Jinbiao, Xu Yin, Wang Jiayuan, Sun Xiaohan
Appl Opt. 2014 Apr 10;53(11):2390-7. doi: 10.1364/AO.53.002390.
A compact polarization rotator (PR) for silicon-based slot waveguides is proposed, where the slot region including the upper claddings is filled with liquid crystals (LCs). With the anisotropic features of the LCs, the transverse field components of eigenmodes have almost identical amplitudes, leading to a high modal hybridness. As a result, the TE (TM) polarization can be rotated efficiently to the TM (TE) polarization within a short length. The numerical results show that a PR 11.3 μm in length at an operating wavelength of 1.55 μm is achieved with an extinction ratio (ER) (insertion loss) of 12.6 (0.22) dB for TE-to-TM and 11.5 (0.30) dB for TM-to-TE. Moreover, the optical bandwidth for TE-to-TM (TM-to-TE) mode must be ∼64(∼29) nm to keep the ER over 12 (10) dB. In addition, fabrication tolerances to the structural parameters are investigated, and field evolution along the propagation distance through the PR is also demonstrated.
本文提出了一种用于硅基槽型波导的紧凑型偏振旋转器（PR），其中包括上包层的槽区域填充有液晶（LC）。由于液晶的各向异性特征，本征模的横向场分量具有几乎相同的幅度，从而导致高模态混合性。结果，TE（TM）偏振可以在短长度内有效地旋转到TM（TE）偏振。数值结果表明，在1.55μm工作波长下，实现了长度为11.3μm的偏振旋转器，其TE到TM的消光比（ER）（插入损耗）为12.6（0.22）dB，TM到TE的消光比（ER）（插入损耗）为11.5（0.30）dB。此外，TE到TM（TM到TE）模式的光学带宽必须约为64（约29）nm，以保持ER超过12（10）dB。此外，还研究了结构参数的制造公差，并展示了沿传播距离通过偏振旋转器的场演化。
