Ultra-low-loss CMOS-Compatible Waveguide Crossing Arrays Based on Multimode Bloch Waves and Imaginary Coupling
Abstract
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.
Cite
@article{arxiv.1311.4277,
title = {Ultra-low-loss CMOS-Compatible Waveguide Crossing Arrays Based on Multimode Bloch Waves and Imaginary Coupling},
author = {Yangyang Liu and Jeffrey M. Shainline and Xiaoge Zeng and Milos A. Popovic},
journal= {arXiv preprint arXiv:1311.4277},
year = {2015}
}