Optical Signal Processing Using Silicon Photonic Devices

Highly integrated micro-electronic technique has made it possible to fabricate billions of transistors in a single silicon chip with very low cost.Ubiquitous integrated circuits make a great contribution to our convenient life and high-speed data interconnection.The development of integrated circuits has followed Moore's law,which means the number of the transistor in a silicon chip doubles every 18 months.However,traditional semiconductor industry cannot follow Moore's law any more due to the physical limit.Also,the terrible transmission delay,power consumption,and crosstalk of the circuit cause a lot of trouble.Now,silicon photonics has become the most promising high-speed interconnect technology,due to its ability to integrate many kinds of photoelectronic devices on a silicon chip,and complementary metal-oxide semiconductor(CMOS)compatibility.On the other hand,with the coming of high-speed information age,both optical fiber communication network and wireless communication network have made a great progress.For the rapid development of optical communication network,one particular trend is that the need for large capacity,tunability,reconfigurability and versatility.In recent researches,silicon devices based optical signal processing has become more and more attractive considering its high speed,dense integration,low cost,and low power consumption.Meanwhile,due to the rapid increase of communication capacity and complexity,the merging of optical system and wireless system has snowballed.Microwave photonic technology combines the advantage of both light and microwave.Thus,high-speed and low-cost integrated microwave photonic signal processing based on silicon photonics also becomes a new research hotpot.In this thesis,high-speed digital optical signal processing and microwave photonic signal processing are investigated using silicon devices.The contents of this thesis are as follows:(1)Two typical types of silicon photonic devices,i.e.silicon wavegduie and microring resonator,are theoretically investigated.(1)The principle of optical signal processing based on nonlinearities of silicon waveguides are discussed.The third-order nonlinear process is discussed,especially the four-wave mixing(FWM).(2)The basic principal of silicon microring resonator is discussed in detail.Both transmission matrix theory and temporary coupled mode theory(TCMT)are adopted.In addition,the nonlinear TCMT is used to study numerous kinds of nonlinear effects in microring resonators,including thermo-optic effect(TOE),two-photon absorption(TPA),free carrier absorption(FCA),free carrier dispersion(FCD)and Kerr effect.(2)Design,fabrication,and test of silicon photonic devices are discussed.(1)We discuss finite-different time-domain(FDTD)method for the design of silicon photonic devices.Four example,microring resonator,grating coupler,directional coupler and multimode interferometer are presented.(2)The fabrication of silicon photonic devices based on electron beam lithography(EBL)and deep ultra-violet lithography(DUV)process are discussed.(3)Test method for silicon photonic devices is introduced.(3)All-optical signal processing based on silicon photonic devices is investigated.(1)On-chip all-optical multi-channel wavelength conversion of quadrature amplitude modulation(16-QAM)signal is experimentally demonstrated in a silicon waveguide.(2)By exploiting a graphene-silicon microring(GSMR),channel-selective wavelength conversion of flexible grid multi-channel 16-QAM signal is proposed and experimentally demonstrated.(3)On-chip all-optical wavelength conversion of 10-Gbit/s 4-level pulse amplitude modulation(PAM-4)signal in a silicon waveguide is experimentally demonstrated.(4)Quaternary/octonary optical computing is realized based on a silicon waveguide.(5)We design and realize a simple on-chip structure to realize optical nonreciprocal transmission.It consists of a silicon microring(nonlinear attenuator)and a directional coupler(linear attenuator).(6)Using a tunable microring resonator and a tunable Mach-Zehnder interferometer(MZI),we realize a fully reconfigurable on-chip diode for optical nonreciprocal transmission.(7)A programmable optical processor is proposed and demonstrated by integrating cascaded arrayed-waveguide gratings(AWGs)with 16 thermo-optic switches on silicon platform.It can realize various kinds of optical processing functions.(4)On-chip microwave photonic signal processing based on silicon photonic devices is studied both theoretically and experimentally.(1)An optically-controlled tunable microwave photonics filter is proposed and experimentally demonstrated.(2)A simple configuration to construct integrated ultrahigh peak rejection MWP filter is proposed and realized experimentally.(3)A peak rejection tunable MWP filter is demonstrated.(4)Microwave signal multiplication is also demonstrated based on a silicon Mach-Zehnder modulator(MZM)in the experiment.(5)In addition,photonic generation of amplitudeshift keying(ASK)microwave signal is also demonstrated based on a silicon MZM.