Quantitative modeling of coupling-induced resonance frequency shift in microring resonators

Qing Li, Mohammad Soltani, Amir H. Atabaki, Siva Yegnanarayanan, Ali Adibi
2009 Optics Express  
We present a detailed study on the behavior of coupling-induced resonance frequency shift (CIFS) in dielectric microring resonators. CIFS is related to the phase responses of the coupling region of the resonator coupling structure, which are examined for various geometries through rigorous numerical simulations. Based on the simulation results, a model for the phase responses of the coupling structure is presented and verified to agree with the simulation results well, in which the first-order
more » ... ch the first-order coupled mode theory (CMT) is extended to second order, and the important contributions from the inevitable bent part of practical resonators are included. This model helps increase the understanding of the CIFS behavior and makes the calculation of CIFS for practical applications without full numerical simulations possible. 19. For example, for the material system used in Ref. [9], Δβ is numerically found to be negative and small (~-0.015 μm 1 at 1578nm for TE polarization, w1/w2 = 400/400 nm, and gap = 100 nm). The corresponding simulation results are shown in Fig. 6 in Ref. [9] . We already know Δψ is negative for this coupling geometry ("CB" coupler), and therefore both terms in Eqs. (23) are negative and the second term is dominant. The two features that 11 (ring-ring phase) is negative (corresponding CIFS positive) and 11 and 22 are of opposite signs are readily understood from Eqs. (23) and (24) . 20. M. Soltani, Novel integrated silicon nanophotonic structures using ultra-high Q resonator, Ph.D. dissertation, Georgia Institute of Technology (2009) 21. M. Popovic, "Complex-frequency leaky mode computations using PML boundary layers for dielectric resonant structures
doi:10.1364/oe.17.023474 pmid:20052055 fatcat:7neovtyqpjgmlf7pmevnwtu5hy