Research On Soliton Self-frequency Shift Effect And Its Application In Slot Chalcogenide-silicon Waveguide

The integration ability of all optical signal processing devices meeting the requirements of future high performance optical communications and signal processing systems is an inevitable trend.Silicon waveguides are robust light guiding media and show great advantages on compact,integratable,low power consumption,flexible dispersion engineering,and compatible with Complementary Metal-Oxide-Semiconductor(CMOS)foundry.Thus,all-optical signal processing technologies using nonlinear effects of silicon waveguides are quite competitive.The thesis mainly studies on the soliton self-frequency shift(SSFS)effect and its applications in chalcogenide-silicon slot waveguide.The main research contents and innovative points are as follows:1.The performance advantages of chalcogenide waveguide for generation of SSFS effect are analyzed.The development of all-optical analog-to-digital converter(AOADC)and mid-infrared(MIR)light sources are reviewed.The theory of optical pulse propagation in waveguides is analyzed.The generalized nonlinear Schrodinger equation(GNLSE)for modeling the pulse propagation and two kinds of efficient numerical methods are derived.The physical mechanism of SSFS and the main parameters determining the amount of frequency shift are discussed.2.The principle of integratable AOADC based on the SSFS effect are reviewed.Several signifciant performance indicators of AOADC are analyzed,e.g.effective number of bits(ENOB),differential nonlinearity error(DNL),and integral nonlinearity error(INL).Comparison of several typical silicon based waveguide structures are carried out by simulations.The results show slot waveguide has more robust light confinement ability.Moreover,the advantages of fabrication of horizontal slot waveguide compared to vertical waveguide are discussed.3.A chalcogenide-silicon slot waveguide filled with As2S3 in the slot layer is designed,which shows large nonlinear coefficient of 139.47 W-1/m at 1550 nm and the wide anomalous dispersion regime of 870 nm.Simulation on all-optical spectral quantization using the proposed waveguide is carried out.Two conditions with and without considering the frequency dependence of nonlinearity are analyzed.By using the optical pulse with width of 100 fs and peak power of 25 W,the wavelength shift of 388 nm is obtained in 5 cm-long waveguide when the frequency dependence of nonlinearity is considered.The corresponding ENOB is calculated to be 2.68-bit without spectral compression.Significant improvement of ENOB is expectable when spectral compression techniques are used after the SSFS process.4.The principles of high-order soliton fission and dispersive wave generation are analyzed.The structure of the proposed slot waveguide is optimal designed.By pumping at the telecom wave band,stable and broadband MIR source is achieved.In the simulation,the first order soliton can be red-shifted up to 2504 nm,which makes the tunable wavelength range in the MIR regime reaches over 500 nm.The maximum conversion efficiency can be up to 42.41%.When a hyperbolic secant pulse pumped at 1560 nm is launched at the peak power of 130 W into the proposed waveguide,the red-shifted dispersive wave(R-DW)is obtained at 2784 nm,along with the bandwidth of 18 nm and the conversion efficiency of 32.28%.The generated tunable MIR waves with high conversion efficiency are potential to be used as MIR sources.