To summarize this entire thesis, MW-assisted spectroscopy has been proposed as a promising approach to investigate the optical properties of VSi and VV spin defects in 4H- and 6H-SiC. The MW-assisted spectroscopy has enabled to separate the spectrally overlapped contribution of different types of defects. From a PL spectrum containing no overlapping spectral contributions of other defects, the local vibrational mode of all measured VSi and VV in 4H- and 6H-SiC has been found along with the phonon energy and DW factor. The interaction of local vibrational modes with point defects has allowed to understand the spin, optical, mechanical, and thermal properties of these defects. In the investigation of V2 in 4H-SiC, a perfect agreement between the experimental data and theoretical calculation have been obtained. The MW-assisted spectra measured at different resonant frequencies associated with the same defect have been found to reveal the same vibrational mode and DW factor. Furthermore, some new ODMR lines to certain defects have been assigned, which have never been reported before. From the investigation of the V2 VSi in 6H-SiC, it has been found that the temperature does not have a clear influence on the DW factor, but high-fluence electron irradiation has been shown to decrease the DW factor. In the polarization investigation, it has been found that in 6H-SiC, V1 possesses no polarization, V2 shows a strong E||c-axis polarization, while V3 exhibits a strong E⊥c-axis polarization. It has also been demonstrated that the temperature and the orientation of the excitation laser have no influence on the photon polarization. In short, this thesis has demonstrated that MW-assisted spectroscopy is a powerful technique to investigate a large number of spin defects in wide-bandgap semiconducting materials.