Compact and Broadband Adiabatically Bent Superlattice-Waveguides With Negligible Insertion Loss and Ultra-Low Crosstalk

Broadband and ultra-low crosstalk integrated silicon superlattice waveguides are proposed and demonstrated, enabling high-density waveguide integration. The superlattice waveguides are implemented as S-shaped adiabatic bends that yield ultra-low crosstalks in the neighboring channels, and an extremely low insertion loss, for the TE polarization. Special materials or complex fabrication steps are not required. The bent superlattice waveguides are measured to have an average insertion loss
$\leq$
0.1 dB for all channels. The average crosstalk values are
$\leq$
−37.8 dB and
$\leq$
-45.2 dB, in the first nearest neighboring waveguide and the second nearest neighboring waveguide, respectively. The transmission spectra are measured over the wavelength ranges of (1.24 μm to 1.38 μm) and (1.45 μm to 1.65 μm), covering both communication wavelengths of 1310 and
$1550 \,\mathrm{n}\mathrm{m}$
. The simulation results predict an efficient broadband performance over the
$500 \,\mathrm{n}\mathrm{m}$
wavelength range (
$1200 \,\mathrm{n}\mathrm{m}$
to
$1700 \,\mathrm{n}\mathrm{m}$
), covering all O, E, S, C, L & U bands. The proof of concept was done for a silicon-on-insulator platform and the approach is applicable to other waveguide geometries and integrated photonic platforms.