Optical fiber waveguides and related approaches are implemented to facilitate communication. As may be implemented in accordance with one or more embodiments, a waveguide has a substrate including a lattice structure having a plurality of lattice regions with a dielectric constant that is different than that of the substrate, a defect in the lattice, and one or more deviations from the lattice. The defect acts with trapped transverse modes (e.g., magnetic and/or electric modes) and facilitates wave propagation along a longitudinal direction while confining the wave transversely. The deviation(s) from the lattice produces additional modes and/or coupling effects.
FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
This invention was made with Government support under contracts DE-FG02-12ER86510 and DE-AC02-76SF00515 awarded by the Department of Energy. The U.S. Government has certain rights in the invention.