Figure 2
From: Integrated photonic guided metalens based on a pseudo-graded index distribution
Design of the metalens, at λ = 1.31 µm, for W = 3 µm, w = 0.35 µm, h = 0.31 µm, P = 250 nm, extreme strip widths e0 = 200 nm and e6 = 50 nm, εc = 3.506 (Si), εsub = 1.4468 (Si02), εg = 1, and εsup = 1. (a) Geometry of FEM mode effective index calculation, considering a periodic array of strips with lateral periodic conditions (dashed lines) and vertical PMLs. (b) Effective index, as a function of strip width e, of the TE mode (blue lines) and the TM mode (red lines), calculated by FEM (solid lines) or second-order EMT (dashed-dotted lines). Inset: (i) Ex field of the TE mode, and (ii) Ey field of the TM mode for a width e = 150 nm.
