Graphene-Incorporated Plasmo-Thermomechanical Infrared Radiation Detection

Metallic nanostructures can be used to selectively absorb a specific regime of the infrared (IR) spectrum depending on its constituent materials and geometry. In this paper, we propose and analyze a plasmo-thermomechanical detector that includes a graphene layer on top of me allic nanowires to enhance the absorption and sensitivity. The proposed device converts the free-space IR radiation to mechanical deformation of nanowires that modulates the insertion loss of the waveguide underneath the nanowires and facilitates the on-chip optical readout of the free-space radiation at room temperature. Our design takes advantage of localized surface plasmon resonances to maximize absorption at the desired IR spectrum. We provide a systematic investigation of different material combinations with and without graphene in addition to variations in detector geometry to optimize the designed IR detector. On top of the absorption enhancement, the graphene layer over the nanowires boosts thermal relaxation speed of the nanowires by 3 times due to graphene's high thermal conductivity, in turn speeding up the response of the IR detection. Moreover, the coated graphene layer enhances the mechanical deformation by a factor of 6 and bends the suspended nanowires downward, enhancing the light-matter interaction between the nanowires and the waveguide evanescent field. Overall, incorporating graphene is beneficial for enhanced spectrum absorption, speed of the IR detection, and optical readout sensitivity. (C) 2020 Optical Society of America