Work

Ultra-low-loss CMOS-compatible waveguide crossing arrays based on multimode Bloch waves and imaginary coupling

Year: 2014

Type: article

Abstract: We experimentally demonstrate broadband waveguide crossing arrays showing ultralow loss of 0.0 4dB/crossing (0.9%) on average and converging to 0.033 dB/crossing (0.075%) matching theory and cross-talk suppression over 35 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 first- and third-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.

Source: Optics Letters

DOI: 10.1364/ol.39.000335

Authors: Yangyang Liu, Jeffrey M. Shainline, Xiaoge Zeng, Miloš A. Popović

Institution: University of Colorado Boulder

Language: English

Topic: Photonic and Optical Devices

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funder: National Science Foundation

Award: Molding Optical Field Patterns for Highly Efficient Design of Strong-Confinement Photonic Devices