Ultrafast All-Optical Switching in the Visible Spectrum with 6H Silicon Carbide

Silicon carbide (SiC) is one of the most promising wide-band gap semiconductors for future technological applications, with the potential for high-temperature and low-loss photonic devices. In this study, we investigated the ultrafast visible light all-optical switching in 6H-SiC, in which nondegenerate two-photon absorption appeared to be dominant. Using an 820 nm femtosecond laser beam as the modulation source, differential transmission on the order of 10% was achieved across the visible spectrum from 420 to 720 nm with the highest modulation depth reaching 27%. The dependence of the optical switching performance on wavelength, fluence, and polarization has been illustrated and analyzed in details. Our results provide an in-depth guideline for exploring SiC, of which the nonlinear optical properties could help to realize ultrafast all-optical switching devices in the visible regime.