Research On Double Fano Resonances Based On Silicon-based Waveguide

Taking great advantages of the sharp-and-asymmetric spectrum which is derived from the superposition of discrete and continuous states under certain phase conditions,Fano resonance is competitive in many fields such as sensors,modulators,and nonlinear optics.For a long time,the single Fano resonance has been investigated in various fields,however,the researches on multi/double Fano resonances are still limited into atomic physics and plasmon systems.Silicon photonics based on silicon-oninsulator(SOI)materials has become a focal point of researches in optics due to its complementary metal-oxide semiconductor(CMOS)-compatible process and many other advantages.To investigate the multi/double Fano resonances in optoelectronic integration,the design and demonstration for double Fano resonances using siliconbased optical waveguides become especially important.In this thesis,we first propose and experimentally demonstrate independently tunable double Fano resonances using silicon-based optical waveguides.The device consists of a U-shaped feedback waveguide embedded by two cascaded micro-ring resonators with different radii.Two discrete beams with sharp waveforms are introduced by the light that only passes through the micro-ring resonators,while a continuous beam with a flat waveform is introduced by the light passing through the large cavity formed by the feedback waveguide with a fixed loss and micro-ring resonators.Different beams are superimposed at the same output port,and finally generated double sharp-and-asymmetric Fano resonances.The device is theoretically modelled by the scattering matrix method and manufactured using CMOS process.The measured results show that the Fano resonances generated by the proposed device have sharp spectra.The extinction ratio of the Fano resonances is improved to be 29.20 dB,and the average slope factor is as large as 83.42 dB/nm.More importantly,the double resonances can be independently tuned when the voltages are applied to the heaters integrated on different micro-rings,which endows the device with practical application prospects in many fields such as high-sensitive biochemical sensors with double sensing area,etc.Reasonable optimizations for the structure of the device are performed to improve the deficiencies shown in the demonstration of the device.Moreover,we also investigated single Fano resonance and double Fano resonances by introducing the proposed configuration to the arms of a symmetric Mach-Zehnder interferometer(MZI).The good performance of the device is predicted successfully through theoretical modeling.