Integrated Terahertz Optics with Effective Medium for 600-GHz-band Imaging

Terahertz waves hold potential in industrial imaging applications, to detect sub-millimeter defects and undesired foreign materials. However, terahertz imaging systems are generally bulky due to the need for optical components, and this is a key issue that has limited the scope of practical applications. In this work, we address this limitation by integrating terahertz optics in micro-structured intrinsic silicon. Four half-Maxwell fisheye lenses and a beam splitter are directly integrated together, and fabricated from a single silicon wafer, to realize a terahertz imaging system for the 600-GHz band. The device is evaluated with both full-wave simulation and experimental techniques. It is found to exhibit ultra-wide bandwidth as a spatial mixer, which is beneficial for low-coherence imaging using a terahertz noise source. The proposed method demonstrates a promising new approach for imaging and sensing applications using compact terahertz devices.