Asymmetric Fano resonance and bistability for high extinction ratio, large modulation depth, and low power switching

Abstract

We propose a two-ring resonator configuration that can provide optical switching with high extinction ratio (ER), large modulation depth (MD) and low switching threshold, and compare it with two other conventional one-ring configurations. The achievable input threshold is n2IIN ~10-5, while maintaining a large ER (> 10dB) and MD (~ 1) over a 10-GHz (0.1 nm) optical bandwidth. This performance can also be achieved by the ring-enhanced Mach-Zehnder interferometer, and is one to two orders of magnitude better than the simple bus-coupled one-ring structures, because of the use of asymmetric Fano resonance as opposed to the usual symmetric resonance of a single ring. The sharpness and the asymmetricity of the Fano resonance are linked to the low switching threshold and the high extinction ratio, respectively, and also accounts for the different dependence on ring dimensions between the one- and two-ring structures.

Nested-ring Mach-Zehnder interferometer in silicon-on-insulator

“…6(right) presents the drop output of a conventional DBRR with 2-µm long race-track and a radius of 15µm also fabricated on the same wafer. The Drop spectra for the DBRR can be curve-fitted with the analytical formula ) cos 2 1 /( 4 2 2 4 r a ar a D + − = δ κ [13], to give an independent derivation of a, where a is the round-trip amplitude factor a = exp(-αL c /2), α is the loss coefficient, δ is the round-trip phase (or normalized frequency) and…”

Lineshape Engineering in an All-Pass Ring Resonator with Backreflection Coupled to a Symmetrical Fabry–Perot Resonator

“…While in many cases, perfect Lorentz lineshape is desired some applications demand more complex resonance lineshapes. For example, narrow electromagnetically induced transparency (EIT) like resonances in RR-based devices can be used for light storage [3], while Fano-like resonances with steep edges and an improved extinction ratio are shown to increase the sensitivity of RR sensors [4] and reduce power threshold for optical switching on a chip [5]. In this work, we propose an all-pass RR with internal backreflection coupled to a symmetrical Fabry-Perot resonator (FPR) for resonance lineshape engineering and control.…”

Nonlinear Mach-Zehnder-Fano interferometer

“…Recently, we have introduced the concept of MachZehnder-Fano interferometer (MZFI) [5] providing with unique physical property that can not be found in a macroscopic resonator enhanced MZI [2][3][4]6]. The MZFI allows us to manipulate the interaction of different types of resonances which leads to the formation of a novel hybrid Fano-like resonant states [7].…”

“…It's their unique property that allows us p-1 arXiv:1201.1630v1 [physics.optics] 8 Jan 2012 to achieve an optimal high extinction ratio, large modulation depth and lowest threshold nonlinear switching [6,17].…”

“…By coupling a resonator to the MZI can further increase the phase sensitivity of the coherent manipulation [2,3]. The enhanced all-optical switching [2] and the bistability [4] have been demonstrated in a coupled ring-resonator Mach-Zehnder interferometer, which provides the possibility for the effective and coherent control by using a nonlinear resonator.Recently, we have introduced the concept of MachZehnder-Fano interferometer (MZFI) [5] providing with unique physical property that can not be found in a macroscopic resonator enhanced MZI [2][3][4]6]. The MZFI allows us to manipulate the interaction of different types of resonances which leads to the formation of a novel hybrid Fano-like resonant states [7].…”