Fluorescence tuning, all-optical switching and OR gate realization of phloroglucinol derived carbon dots

Carbon dots that display unusual optical properties are promising materials for photonic applications. Surface passivation of carbon dots improves its optical properties, enabling full-colour emission and excitation dependent emission, making them ideal candidates for bio-imaging. We observed multicolour emission from phloroglucinol-derived carbon dots with surface passivation. Tuning the emission spectra from ultraviolet to visible spectra is achieved with varying surface passivation. Nonlinear optical properties of the samples were studied using spatial self-phase modulation. Power and wavelength dependent variation of nonlinear optical properties are investigated. All-optical switching is achieved from the sample using spatial cross-phase modulation. We have successfully demonstrated an all-optical OR gate with a switch laser and a signal laser. With appropriate control of the switching time, spatial division multiplexing of different signals or different typetypes of data can be encrypted using the same setup. Experimental results show that these carbon dots have better nonlinear optical properties for application in all-optical switching, OR gate and space division multiplexing.