Open AccessInverse design of a single-step-etched ultracompact silicon polarization rotator
Author(s) -
Weijie Chang,
Shengyao Xu,
Mengfan Cheng,
Deming Liu,
Minming Zhang
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.399052
Subject(s) - extinction ratio , optics , materials science , polarization (electrochemistry) , waveguide , polarization rotator , fabrication , photonic integrated circuit , inverse , silicon photonics , birefringence , silicon , optoelectronics , photonic crystal , physics , wavelength , medicine , chemistry , alternative medicine , pathology , geometry , mathematics
We propose and experimentally demonstrate a novel ultracompact silicon polarization rotator based on equivalent asymmetric waveguide cross section in only single-step etching procedure for densely integrated on-chip mode-division multiplexing system. In the conventional mode hybridization scheme, the asymmetric waveguide cross section is employed to excite the hybridized modes to realize high performance polarization rotator with compact footprint and high polarization extinction ratio. However, the fabrication complexity severely restricts the potential application of asymmetric waveguide cross section. We use inverse-designed photonic-crystal-like subwavelength structure to realize an equivalent asymmetric waveguide cross section, which can be fabricated in only single-step etching process. Besides, a theory-assisted inverse design method based on a manually-set initial pattern is employed to optimize the device to improve design efficiency and device perform. The fabricated device exhibited high performance with a compact footprint of only 1.2 × 7.2 µm 2 , high extinction ratio (> 19 dB) and low insertion loss (< 0.7 dB) from 1530 to 1590 nm.