Extended Data Fig. 1: Schematic of a two-element system with unidirectional microring resonators and a link structure.
From: Gain-induced topological response via tailored long-range interactions
The directional couplers provide a π phase difference between the coupling terms κ1→2 and κ2→1. The coupling phase kL can be changed by varying the length L = 2Lc + Lm.
