All-optical Logic Gates And Optical Frequency Combs Based On The Planar Waveguides And Microresonators

Planar waveguides and microresonators are basic units in integrated optical systems,which have the characteristics of small size,strong light field confinement and flexible dispersion control.They have become ideal platforms for studying on-chip nonlinear optical effects and applications.Based on the four-wave mixing（FWM）effect in the planar waveguides and microresonators,many technologies have been developed,such as optical parametric amplification,optical parametric oscillation,time lens,all-optical logic gate,Kerr optical frequency comb,which have become one of the most concerned research hotspots and frontier fields at present.In this dissertation,the structure parameters of the planar waveguide and microresonator based on multiple material platforms are designed and optimized.The influence of various effects on the four-wave mixing process in the planar waveguides and microresonators are also investigated.Correspondingly,the high-speed,tunable all-optical logic gates and broadband mid-infrared microresonator optical parametric oscillation are realized.The main research contents and achievements are as follows:Firstly,a novel silicon-organic hybrid（SOH）double slots waveguide is proposed,overcoming the impact of two-photon absorption and free carrier effects.By optimizing the waveguide geometry parameters,the high nonlinearity(γ=1.4×10⁴ W^-1m^-1)and near-zero flat anomalous dispersion are achieved in the communication band.The all-optical logic AND,OR and XOR gates for 100 Gbit/s data signals based on the FWM in this waveguide are realized,and the conversion efficiency is as high as-6.5 d B.At the same time,the influence of two-photon absorption and free carrier effects on the FWM process and all-optical logic gates in the silicon waveguide are theoretically studied.The results show that the two-photon absorption and free carrier effects can lead to waveform distortion and conversion efficiency reduction.Secondly,a silicon-graphene hybrid（SGH）microring resonator is presented,which can offer flat anomalous dispersion by optimizing the structure parameters.Also,it has a broadband tunable dispersion and multiple zero-dispersion wavelengths by actively adjusting the chemical potential of the graphene sheet.The tunable all-optical AND logic gate functioning for 40 Gb/s signals can be obtained over a wavelength range from 1536 nm to 1569 nm via the FWM effect in the microring resonator,and the conversion efficiency is about-6.4 d B.Additionally,the influence of high-order dispersions on the FWM process and all-optical logic gate based on the microring resonator is numerically analyzed.It is found that the high odd-order dispersion can induce the temporal drift and tail oscillation of the output pulses,while its direction is determined by the positive or negative sign of the third-order dispersion.The high even-order dispersion will lead to the waveform broadening and conversion efficiency decreasing.At last,the generation characteristics and dynamic process of the mid-infrared optical frequency comb based on the cascaded FWM effect in magnesium fluoride（Mg F₂）micro-disk resonator are numerically investigated.The transition from modulation instability state to stable single soliton state via optimizing the pump detuning is observed.The temporal and spectral evolution dynamics of the single soliton formation are also revealed by scanning the pump-laser detuning,and the system parameters of the mid-infrared microcavity soliton optical frequency comb are obtained.On this basis,a Mg F₂ resonator with high quality factor and near-zero anomalous dispersion is obtained by optimizing the resonator’s geometry parameters.Meanwhile,the chalcogenide（As₂S₃）tapered fibers are fabricated as a desirable coupler.The experiment system of the mid-infrared microcavity optical frequency comb generation is built based on a Mg F₂ micro-disk resonator and a miniaturized quantum cascade laser centered at 4.78μm.The mid-infrared optical parametric oscillation over a spectral bandwidth of approximately 4380 nm is realized by adjusting the pumping wavelength,power and the coupling position between the tapered fiber and the microresonator.