Figure. 1 | Double-coupled waveguides for polarization-controlled chiral transport. (IMAGE)
Caption
Figure. 1 | Double-coupled waveguides for polarization-controlled chiral transport. a, b Modal field and index variations for TE and TM polarizations by changing the upper (a) and lower (b) widths of the single L-shaped waveguide. Below the modal field distributions, n denotes the modal index. The lower and upper widths of the baseline waveguide are Wb = 700 nm and Wa= 350 nm, respectively, and their width variations are ΔWa = ΔWb =100 nm. c Dual-coupled waveguides for demonstrating polarization-controlled chiral transport. The cross-sectional parameters are marked in the left panel. The blue line with arrows in the right panel show the evolution trajectory, where its projection onto (β ⁄ κ, γ ⁄ κ) plane is marked by the brown line. d, e β versus WLa and WLb at 1550 nm for TE (d) and TM (e) polarizations, with WR being fixed at 450 nm. The white straight lines represent the structural parameter variations from O to A-. f β as a function of the propagation distance, z. The entire silicon waveguides are covered by a 1-μm-thick SiO2 layer, with the refractive indices of Si and SiO2 being of 3.478 and 1.444 at 1550 nm, respectively. The full height of L-shaped waveguide is ha = 340 nm, and the height of the lower waveguide is hb = 220 nm. The modal field distributions in a, b are obtained by FDTD simulations.
Credit
by Hang Zhu, Jian Wang, Andrea Alù and Lin Chen
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CC BY