On-Chip Broad Spectrum Light Source Generation Based On Dispersion Control And Dispersion Measurement Technology

In recent years,the development of integrated silicon photonic waveguides has received extensive attention.The high index contrasts and high mode confinement of optical waveguides make them widely used for integrated optoelectronic devices.Silicon photonic nonlinear materials have large nonlinear refractive index,and the dispersion of silicon photonic devices can be flexibly adjusted by changing the structural parameters.Therefore,the silicon photonic technology can be combined with nonlinear optics,and some nonlinear phenomena such as supercontinuum and optical frequency comb generation can be researched in silicon photonic devices.Supercontinuum generation in silicon photonic waveguides and its application is one of the research hotspots.In addition,before conducting experimental research on the supercontinuum generation in optical waveguides,it is necessary to measure the dispersion of the waveguides.However,it is difficult to measure the low dispersion currently.Optical fiber is a mature waveguide structure,whose dispersion can be measured in many ways.Further research on fiber dispersion measurement will provide new ideas for the development of the dispersion measurement of silicon photonic waveguides to a certain extent.Based on the points mentioned above,this thesis studies the supercontinuum generation in silicon photonic waveguides pumped by picosecond pulses based on dispersion control,explores the mechanisms of spectrum broadening,then uses the supercontinua obtained in the waveguide to generate few-cycle pulses.On the other hand,this thesis uses microwave photonics technology to design a dispersion measurement system based on multi-plane light converter,which realizes the simultaneous measurement of chromatic and modal dispersion of few-mode fibers.The main works of this thesis are as follows:For broad spectrum light source generation,this thesis uses the silicon nitride waveguide with saddle-shaped dispersion to generate two-octaves supercontinua(656-3867 nm)with the spectrum flatness better than 15 d B pumped with picosecond pulses.The coherence of the generated supercontinua and the stability with different incident pulse parameters or waveguide structure parameters are analyzed.Then,using the silicon nitride slot waveguide proposed in the previous research,the supercontinuum from 615 nm to 2662 nm is generated.A bandpass filter is designed and optimized to filter out some frequency components of the generated supercontinuum,and an ultrashort laser pulse with a pulse width of 5.0 fs which corresponds to 1.4 optical cycles is obtained.Finally,the filters needed in the follow-up experiment are investigated preliminarily.For dispersion measurement,this thesis studies the dispersion measurement method based on microwave photonics technology,and proposes an integrated dispersion measurement scheme for few-mode fibers based on multi-plane light converter and the photodetector with multi-mode pigtail,which achieves high-precision measurement of the chromatic dispersion and the differential mode group delay relative to fundamental mode of the 36.251-km-long two-mode fiber.The scheme is extended to the characterization of fibers which can conduct more modes,and the differential mode group delay relative to fundamental mode of a four-mode fiber is measured.The proposed scheme simplifies the experimental operation,and strives to play a leading role in the development of the dispersion measurement of silicon photonic waveguides.