Fig. 1. Optical characterization of Nb₂C. (a) SEM image of Nb₂C; (b) linear absorption spectra of Nb₂C nanosheet

Fig. 2. Nonlinear absorption characteristics of few layers of Nb₂C nanosheets at wavelength of 1550 nm. (a) Z-scan experimental results; (b) relationship between normalized transmittance and intensity of incident light

Fig. 3. Experimental apparatus for all-optical wavelength conversion

Fig. 4. Four-wave mixing spectra of different signals. (a) No radio frequency signal; (b) radio frequency at 10 GHz

Fig. 5. Performance curves at different pump wavelength intervals and pump power. Under different pump wavelength intervals, (a) output spectrum, (b) conversion efficiency; under different pump power, (c) output spectrum, (d) conversion efficiency