Light absorption performance of nanowire photodetectors based on plasmon antennas

By aiming at the limitations of Si nanowire photodetectors in the infrared band, this paper proposes a design of a nanowire photodetector integrated with coupled butterfly-shaped Au plasmonic antennas. Through numerical simulations, it utilizes the coupled plasmon resonance effect caused by the coupled butterfly-shaped Au slices to provide local electric field enhancement in the device, hence increasing the device's light absorption capability. It is shown that the devices modified by coupled butterfly-shaped Au slices have obvious polarized light dependence. The coupled butterfly-shaped Au slices introduce an absorption peak with a peak absorption rate close to 40% in the waveband range of 1-3 µm, which can be regulated by their structural parameters, such as the distance between the Au slices, the length of the inner edge length, the height of the Au, and the connection mode between the Au slices. When the two Au slices are connected by a bridge, two absorption peaks appear on the absorption curve under the parameter conditions of <i>d</i><i>i</i><i>s</i>=5<i>n</i><i>m</i>, <i>s</i>1=12<i>n</i><i>m</i>, and <i>h</i>=18<i>n</i><i>m</i>. The peak absorptions are up to 25% and 40%, respectively, which greatly breaks through the limitations of the application of Si nanowire photodetectors in the infrared wavelength band and provides a certain way of thinking about the enhancement of the device photo-absorption performance.