Wax/PTFE Substrate Lens for Front-side Illumination of TeraFET Detectors

A composite wax/PTFE lens integrated on the front-side of Si CMOS TeraFET detectors is demonstrated in order to optimize the coupling efficiency of the THz radiation. The wax/PTFE lens is fabricated by first dripping molten wax onto the detector to embed and protect the bonding wires, then pasting a custom-designed hemispherical PTFE lens onto this layer exploiting the adhesive character of the soft wax. The experimental results show a 10-dB injection efficiency enhancement compared with the case without the wax/PTFE lens, and a 20-dB dynamicrange increase in Fourier imaging.