Fig. 1. Schematic of the waveguide superlattices with AGF.

Fig. 2. (a) Band-gap diagram (first two minibands) of a typical straight waveguide array for a=2.65μm, w1=1μm, w2=0.85μm, Δn=0.31, λ=1.55μm, and n0=1.450, where the propagation constant is plotted as a function of the Bloch wave number and the shaded regions represent the bands. (b) Ninth-order (J9) and tenth-order (J10) Bessel modulation of the first kind. J10 and J9 have the same sign in the marked red region.

Fig. 3. Simulated normalized field evolution in (a) normal waveguides, (b) ordinary superlattice, (c) AGF waveguide array, and (d) AGF-enabled superlattice, where gap = 400 nm, L=200μm. Schematic top views of the simulated structures are located at the corners of each subimage.

Fig. 4. Simulated crosstalk in the designed waveguide array (gap = 400 nm, λ=700 to 1700 nm) when (a) fundamental TE mode and (b) fundamental TM mode are launched, respectively. The pink planes correspond to −28 and −25dB, respectively.

Fig. 5. (a) The top-view microscope image of the fabricated device on the Si3N4 platform (gap=400nm, L=200μm). (b) SEM image of the cross section of a waveguide (gap=400nm, L=200μm). (c) The top-view microscope image of the fabricated device on the Si3N4 platform (gap=500nm, L=1mm). (d) Experimentally recorded light trajectory in modulated samples for 850 nm.

Fig. 6. (a) Measured transmission spectra of the AGF-enabled superlattice (gap=400nm). (b) Measured transmission spectra of the AGF-enabled superlattice (gap=500nm). The pink planes correspond to −24 and −28dB, respectively.

Fig. 7. Simulated crosstalk for AGF-enabled superlattice with (a) ΔA=−50nm and (b) ΔA=+50nm. The pink planes correspond to −20dB.

Fig. 8. Simulated crosstalk for AGF-enabled superlattice that widths of all waveguides (a) increase by 25 nm and (b) decrease by 25 nm. The pink planes correspond to −20dB.

Fig. 9. (a) Measured SNR profiles of the system after transmission through the waveguide array. (b) The bit allocation of 112-Gbit/s DMT signals. Inset: constellations of different subcarriers.