33 research outputs found
Ultra-low-loss CMOS-Compatible Waveguide Crossing Arrays Based on Multimode Bloch Waves and Imaginary Coupling
We experimentally demonstrate broadband waveguide crossing arrays showing
ultra low loss down to dB/crossing (), matching theory, and
crosstalk suppression over dB, in a CMOS-compatible geometry. The
principle of operation is the tailored excitation of a low-loss spatial Bloch
wave formed by matching the periodicity of the crossing array to the difference
in propagation constants of the 1- and 3-order TE-like
modes of a multimode silicon waveguide. Radiative scattering at the crossing
points acts like a periodic imaginary-permittivity perturbation that couples
two supermodes, which results in imaginary (radiative) propagation-constant
splitting and gives rise to a low-loss, unidirectional breathing Bloch wave.
This type of crossing array provides a robust implementation of a key component
enabling dense photonic integration