Optics Letters
Loss-induced switching between electromagnetically induced transparency and critical coupling in a chalcogenide waveguide
Bin Zhang, Yaodong Sun, Yi Xu, Guiying Hu, Pingyang Zeng, Mingqi Gao, Di Xia, Yufei Huang, Zhaohui Li
Abstract
Optical loss is generally perceived to be an adverse effect in integrated optics. Herein, in contrast, we propose a mechanism to harness the loss in a coupled ${\rm {high-}}{\! Q}$ resonators system to realize on-chip electromagnetically induced transparency (EIT). The increasing loss of one of the coupled resonators results in a difference in ${Q}$ factor, leading to EIT generation. This optical loss-induced EIT is studied analytically using the coupled-mode theory and demonstrated experimentally in chalcogenide coupled microring resonators. By taking advantage of the chalcogenide phase change materials that feature exceptional optical property contrasts, we further demonstrate the loss-induced mechanism to realize fast and nonvolatile responses between the EIT state and the critical coupling state in a monolithically integrated chip. Our results provide a new perspective to harvest the negative loss effect of coupled resonators for tunable photonic devices, which might shed new light on the design ideology for on-chip slow-light optical components.