A broadband enhanced plasmonic modulator based on double-layer graphene at mid-infrared wavelength

Graphene is as an essential material for light modulation owing to controlling broadband absorption and plasmon excitation. Here, we propose a mid-infrared enhanced plasmonic modulator that integrates double-layer graphene in a reflective structure. It is demonstrated that double-layer graphene can support plasmonic resonances with higher oscillator intensity than single-layer in this modulator. The proposed modulator exhibits a modulation depth up to 21 dB and 3 dB bandwidth of 47.4 GHz over a wide range of wavelength (3.17 µ m to 4.4 µ m). Moreover, the maximum insertion loss of it is barely about 0.27 dB and the minimum of that is about 0.1 dB. This graphene-based modulator, with combined advantages of high modulation depth, low insertion loss and ultrafast modulation speed, holds potential in efficient manipulating MIR lights in free space communication.