Surface Plasmon Nanoantenna-Based Photodetector with Terahertz Electrical Bandwidth

A surface plasmon nanoantenna-based photodetector is proposed and investigated. An array of nanodipoles on an InP substrate is assumed, where the detection region consists of volumes of InGaAs located in the gaps of the nanodipoles. The responsivity of the photodetector is estimated to be similar to 100 mA/W at its peak value. A trend is observed for the power absorption in the detection region as a function of gap size; an optimum gap size exists that maximizes the product of the gap volume and the electric field enhancement in the gap. The 3 dB electrical bandwidth of the device is calculated assuming conventional and ballistic carrier transit in the detection region, yielding 0.7-4 THz.