Nonlinear Optical Properties Of Silicon Carbide Semiconductor Materials And Ultrafast Optical Dynamics Study

In this thesis, we investigated the nonlinear optical properties and the ultrafast optical dynamics of SiC semiconductor materials by using z-scan, time-resolved optical Kerr effect (OKE) and femosecond (fs) pump-probe techinques.The main contents are as follows:1. Introduced the molecule structure, growth technique and the research development of SiC semiconductor materials, eapecially those latest results about optical properties and ultrafast dynamics.2. Z-san, OKE and pump-probe settings using fs laser system are described, theories utilized to manipulate data are discussed.3. The optical absorption spectra of pure SiC bulk and the nitrogen-doped SiC bulks are measured and explained. Ultrafast third-order nonlinear optical response of bulk 6H-SiC undoped and doped with different nitrogen concentrations were investigated utilizing femtosecond (fs) z-scan and optical Kerr effect (OKE) techniques at the wavelength of 800 nm. The z-scan measurement shows that the third-order nonlinear optical susceptibilities of the doped samples are improved in comparison to the intrinsic sample. The OKE results additionally reveal that the instantaneous nonlinear optical response of the samples can be ascribed to the distortion of the electron cloud. The ultrafast transient spectroscopic measurements with the one-color and two-color pump-probe techniques demonstrate that the ultrafast recovery process in subpicosecond domain is induced by two-photon absorption process, while the slow relaxation component reflects the carrier dynamics.