|
Currently, optical antenna has already become a research hotspot because of its remarkable local field enhancement effect and resonance propagation characteristics. Optical antennas are usually designed as a type of sub-wavelength-scaled metal structures. By transmitting the field enhancement signal of the optical antenna to the infrared detector, the weak signal detection ability of the infrared detector can be improved. As demonstrated, the resonant wavelength of the local surface plasmons is determined by the structure and material of the antenna and also the material properties of the surrounding medium. By changing the geometry of the antenna or the dielectric characteristics of the circumstance medium, the response frequency of the optical antenna can be regulated. As a two-dimensional material with unique electrical and optical properties, the dielectric properties of graphene can be regulated by applied bias voltage. By selecting the geometry of the antenna and applying bias voltage, the optical antenna with unique characteristics can be obtained. In this paper, an optical antenna with a graphene-silica-silicon trilayer structure is designed and a planar-tip array is fabricated over the graphene layer. The influence of the geometry of the planar-apex array and the thickness of the silica dielectric layer corresponding to the optical properties of the graphene antenna are analyzed. Simulation results show that by changing the shape of the planar-tip and the thickness of the silica dielectric layer, the position and intensity of the absorption peak of the graphene optical antenna can be controlled effectively. At the same time, under the control of external bias voltage, the resonance peak also appears an obvious movement of a maximum range of about three microns.
|
