A plasmon modulator by dynamically controlling the spatial distribution of carrier density in graphene

Light–matter interaction at the nanoscale is of particular interest for future photonic integrated circuits and devices with applications ranging from communication to sensing and imaging. In this letter, we proposed a plasmon modulator to enhance the Light–matter interaction by dynamically controlling the spatial distribution of carrier density at the nanoscale, which is demonstrated by a hybrid graphene-dielectric-grating structure. The numerical results show that both the applied voltage and the grating period can be utilized to modulate the surface plasmon polaritons (SPPs) effectively. The modulator can also work on an ultra-wideband in theory as the scattering effect is independent of the wavelength. Compared with the modulator via changing the whole carrier density, the modulation depth by controlling the spatial distribution of carrier density at the nanoscale has improved about 18.6 dB at the working wavelength of 12.4μm. This plasmon modulator triggers an approach for the enhancement of Light–matter interaction at the nanoscale and improves the modulation depth significantly, which will have a potential application in the fields of optical switches, sensor and photo-detection. •We proposed a new method to enhance the Light–matter at nanoscale by controlling the spatial distribution of the carrier density in graphene, which paved the way to further minimize the future optoelectronic device.•Both the voltage and the period of grating have a good modulation performance on the propagating surface plasmon polaritons (SPPs).•As the scattering effect is independent of the wavelength, proposed modulator triggers an approach for the realization of ultra-wide band modulation.•The modulation depth have improved 18.6 dB at the working wavelength of 12.4 μm compared with the modulator via controlling the whole carrier density.