Open AccessNumerical design of a high-performance polarization beam splitter assisted by composite subwavelength gratings
Author(s) -
ChiaChien Huang,
Cheng-Shong Wu,
ChiaChien Huang
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.391897
Subject(s) - extinction ratio , materials science , optics , fabrication , silicon on insulator , insertion loss , polarization (electrochemistry) , optoelectronics , beam splitter , strips , coupling loss , transverse plane , wavelength , waveguide , silicon , electron beam lithography , resist , layer (electronics) , physics , optical fiber , medicine , laser , chemistry , alternative medicine , structural engineering , pathology , composite material , engineering
We report a compact polarization beam splitter (PBS) consisting of slotted waveguides assisted by composite subwavelength gratings (CSWGs) on a silicon-on-insulator platform. By tailoring the material anisotropy of the CSWGs, coupling strengths of transverse-electric (TE) and transverse-magnetic (TM) polarization coupling strengths are respectively suppressed and enhanced significantly, achieving concurrent improvements in polarization extinction ratio (PER), device footprint, and working bandwidth (BW) compared with purely slotted waveguides. Differing in construction from mono-material SWGs, the CSWGs comprise silicon strips covered with a silicon dioxide (SiO 2 ) layer of the same thickness as the slot layer of the slotted waveguides, simplifying the fabrication process and further reducing device length. Numerical simulations show significant improvement in PER TM from about 15 dB for the purely slotted waveguides to 28 dB for the proposed design, with a 40% reduction in device length at a wavelength of λ = 1550 nm. Within a BW of ∼60 nm, the proposed PBS achieves PER TM ∼25 dB, PER TE >15 dB, and insertion loss (ILs) <0.1 dB for TE and TM modes. Fabrication tolerance investigations are also described and discussed. The proposed idea paves the way for simultaneous improvements in PER, footprint, and working BW for PBSs comprising a variety of coupled-waveguide systems.