Robust optical delay lines with topological protection

Abstract

Phenomena associated with topological properties of physical systems are\nnaturally robust against perturbations. This robustness is exemplified by\nquantized conductance and edge state transport in the quantum Hall and quantum\nspin Hall effects. Here we show how exploiting topological properties of\noptical systems can be used to implement robust photonic devices. We\ndemonstrate how quantum spin Hall Hamiltonians can be created with linear\noptical elements using a network of coupled resonator optical waveguides (CROW)\nin two dimensions. We find that key features of quantum Hall systems, including\nthe characteristic Hofstadter butterfly and robust edge state transport, can be\nobtained in such systems. As a specific application, we show that the\ntopological protection can be used to dramatically improve the performance of\noptical delay lines and to overcome limitations related to disorder in photonic\ntechnologies.\n