Rearcher On Nonlinear Optical Characters Of Silicon Nanometer Waveguide And Application In Supercontinuum Generation

Silicon photonic wire(SPW) is extensively investigated and applied for its remarkable dispersion engineering and high nonlinearity which derived from its ultrostructure and high light confinement.In this paper, the theory and application for dispersion and nonlinear in silicon wire are researched in detail, which includes nonlinear propagation of ultro-short pulse, modulation instability and supercontinuum generation in silicon wire. The major investigation achievements are as follows:1The development and nonlinear properties of SOI(silicon-on-insulator) waveguide are summarized. The nonlinear propagation equations which meet to the propagation of single beam and two beams are deduced based on the Maxwell equations. Numerical solution for pulse propagation equation is obtained by adopting symmetrical split-step-Fourier-method and Runge-Kutta method as well.2The GVD(group velocity dispersion) of silicon wires with different configurations are caculated with FEM(finite element method). The result indicates that the configuration parameters decide the dispersion properties of silicon wires. The silicon wires with different sizes may possess the same GVD at certain wavelength.3The affections of dispersions, nonlinear effects and losses on propagation of single pulse are analysissed qualitatively based on nonlinear Scoording equation. The time domain and spectrum properties of propagating picosecond pulse are soluted numerically when considering (SPM) self-phase-modulation, TPA(two-photonics-absorbtion), FC(free-carrier) effect and all kinds of dispersions.4The modulation instability induced by SPM(self-phase modulation) in single beam and the modulation instability arises from XPM(cross-phase modulation) between two beams are investigated respectively based on nonlinear Scoording equation, when considering linear loss. All factors which affect on the spectrum gain of modulation instability are demonstrated theoretically, the related simulations are carried out as well.5The mechanism of supercontinuum generation arised from the propagation of femtosecond pulse in silicon wire is investigated theoretically and numerically, when taking the silicon wire with configuration of W×H=0.8um×0.7um for example.The modified nonlinear Scooding equation which meets to propagation of femtosecond pulse in silicon wire is soluted numerically by using symmetrical split-step-Fourier-method and Runge-Kutta method. The affections of GVD, higher order dispersion, SPM, TPA(two-photonic-absorbtion) and FCA(free-carrier-absorbtion) on supercontinuum are analyzed in detail. A scheme of multicarrier source based on silicon photonic wire is proposed as well. Numerical simulation shows that the proposed scheme can provide supercontinuum output with3dB spectrum width of220nm, space of25Ghz and about1000effective channels, which should useful in practical applications.