Femtosecond laser-induced periodic structures, so-called "ripples", were systematically studied under various incident laser wavelengths and polarization properties. The effect of the excitation wavelength on the period of ripples was investigated from the infrared to ultraviolet laser pulses. The period of ripple on 4H-SiC correlated remarkably with the wavelength of the incident laser beam. This means that the period of ripples can be controlled by the wavelength of the laser beam. The irradiation of circular polarized femtosecond laser beam produced dot-like structures with the mean spacing of about 200 nm on the surface of 4H-SiC. The effect of initial surface roughness was also studied.