Optically tunable Fano resonance in a grating-based Fabry–Perot cavity-coupled microring resonator on a silicon chip

Abstract

A grating-based Fabry-Perot (FP) cavity-coupled microring resonator on a silicon chip is reported to demonstrate an all-optically tunable Fano resonance. In the device, an add-drop microring resonator (MRR) is employed, and one of the two bus waveguides is replaced by an FP cavity consisting of two sidewall Bragg gratings. By choosing the parameters of the gratings, the resonant mode of the FP cavity is coupled to one of the resonant modes of the MRR. Due to the coupling between the resonant modes, a Fano resonance with an asymmetric line shape resulted. Measurement results show a Fano resonance with an extinction ratio of 22.54 dB, and a slope rate of 250.4 dB/nm is achieved. A further study of the effect of the coupling on the Fano resonance is performed numerically and experimentally. Thanks to the strong light-confinement capacity of the MRR and the FP cavity, a strong two-photon absorption induced nonlinear thermal-optic effect resulted, which is used to tune the Fano resonance optically.

Wideband excitation of Fano resonances and induced transparency by coherent interactions between Brillouin resonances

“…Since the criterion for the occurrence of Fano resonance involves coherent interaction between two excitation paths, the phenomenon is considered quite generic. Till date, Fano resonances have been observed in many complex dynamical systems such as atomic-plasmonic coupling system 2 ; mechanical excitations in nano-optomechanical structures 3 , 4 ; biased semiconductor super lattices 5 ; Fano effect in quantum dots 6 , 7 ; Weyl fermions 8 ; waveguide-cavity systems 9 – 11 ; perovskites 12 ; optically driven atomic force microscopy 13 ; and forward stimulated Brillouin scattering (FSBS) 14 – 17 . Fano resonance finds tremendous applications in microwave spectroscopy of high absorption matter 18 , 19 ; bio-sensors 20 ; ultrafast switching 21 ; and Fano laser 22 , 23 .…”

Fano lines in the reflection spectrum of directly coupled systems of waveguides and cavities: Measurements, modeling, and manipulation of the Fano asymmetry

“…This tuning has been arXiv:1610.08351v2 [physics.optics] 27 Jun 2017 achieved by tuning the cavity resonances [15,[20][21][22]. For a given cavity, by deliberate design of the coupling to the continuum, different Fano line shapes can be obtained by fabricating different samples [17,23,24]. However, after the structure is fabricated, it is very difficult to change the Fano line shape without changing the frequency of the resonance because this requires to change the properties of the continuum or the broad resonances.…”

A novel approach to create a tunable Fano resonance with an extinction ratio over 40 dB

“…Various approaches have been reported to demonstrate a Fano resonance in silicon photonics, but a satisfying solution towards a fully integrated circuit with an efficient tuning mechanism to generate a fully tunable Fano resonance with adequate extinction ratio (ER) and slope rate is still missing [2], [3]. In this paper we propose a novel method based on an integrated photonics circuit on silicon-on-insulator platform.…”