Toward high-performing topological edge-state optical isolators
© 2019 American Physical Society. Publisher's version of record: https://doi.org/10.1103/PhysRevApplied.11.034045
We report on the experimental implementation of topological edge-state arrays with power confinement in the edge state as high as 29 dB relative to its farthermost channel. Average insertion losses of <2 dB in the edge channel vs total output power in the whole array are measured. The device follows a Su-Shrieffer-Heeger>construction, consisting of seven waveguides fabricated on (100) liquid-phase-epitaxy-grown bismuth-substituted lutetium iron garnet films on a gadolinium gallium garnet substrate. The delocalization of the field can be realized by magnetizing only the single edge-state channel, thereby diverting the backscattered signal to serve as a high-performing optical isolator with a predicted isolation ratio as high as −50 dB. We discuss methods and challenges for full experimental implementation of a SSH topology-based optical isolator.