Modeling quasi-dark states with temporal coupled-mode theory

Author(s)

Souza, Mario C. M. M. ; Rezende, Guilherme F. M. ; Barea, Luis A. M. ; Wiederhecker, Gustavo S. ; Frateschi, Newton C.

• Document type: Journal article
• Source: Optics Express; v. 24, n. 17, p. 18960-18972, AUG 22 2016.
• Web of Science Citations: 6

Abstract

Coupled resonators are commonly used to achieve tailored spectral responses and allow novel functionalities in a broad range of applications. The Temporal Coupled-Mode Theory (TCMT) provides a simple and general tool that is widely used to model these devices. Relying on TCMT to model coupled resonators might however be misleading in some circumstances due to the lumped-element nature of the model. In this article, we report an important limitation of TCMT related to the prediction of dark states. Studying a coupled system composed of three microring resonators, we demonstrate that TCMT predicts the existence of a dark state that is in disagreement with experimental observations and with the more general results obtained with the Transfer Matrix Method (TMM) and the Finite-Difference Time-Domain (FDTD) simulations. We identify the limitation in the TCMT model to be related to the mechanism of excitation/decay of the supermodes and we propose a correction that effectively reconciles the model with expected results. Our discussion based on coupled microring resonators can be useful for other electromagnetic resonant systems due to the generality and far-reach of the TCMT formalism. (C) 2016 Optical Society of America (AU)

• FAPESP's process: 08/57857-2 - Photonics for optical communications
• Grantee: Hugo Luis Fragnito
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 14/04748-2 - Coupled microresonators applied to signal processing and photonics integration
• Grantee: Mário César Mendes Machado de Souza
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 12/17765-7 - Nanophotonics in Group IV and III-V semiconductors
• Grantee: Gustavo Silva Wiederhecker
• Support type: Research Grants - Young Investigators Grants