Coherent white emission of graphene

The coherence properties of broadband white light emitted by graphene foam after irradiation with intense light of laser diodes were investigated. The interference fringes assigned to spatial and temporal coherence were observed for graphene white-light emission excited by two different excitation wavelengths of 975 nm and 808 nm of laser diodes. Both light sources were spectrally filtered to a narrow bandwidth in order to exclude the effect of temporal coherence. It was found that the coherence degree of white light emission of graphene differs depending on the excitation wavelength; however, no excitation power effect on the coherence degree was observed. The origin of coherence of laser-induced white emission of graphene is the stimulated emission due to the inversion population.