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Abstract The design of antennas for terahertz systems remains a significant challenge. These antennas must provide very high gain to overcome significant free-space path loss, which limits their ability to broadcast or receive a beam over a wide angular range. To circumvent this limitation, here we describe a new device concept, based on the application of quasi-conformal transformation optics to the traditional Luneburg lens. This device offers the possibility for wide-angle beam steering and beam reception over a broad bandwidth, scalable to any frequency band in the THz range. 

We demonstrate a bar code sensing system for the THz region using leaky parallel plate waveguide and an off-axis parabolic mirror. The bars of the bar code are made from metal with air as gaps between them. We use up to 6 bars in the barcode system which can store up to 64 bits. Because the system employs coherent detection, we can further increase the bit density by adding Teflon strips to the barcode, encoding information in both amplitude and phase delay. These bar codes can be manufactured easily and inexpensively, offering a versatile alternative to RFID tags. 

Terahertz technology has greatly benefited from the recent development and generalization of prototyping technologies such as 3D printing and laser machining. These techniques can be used to rapidly fabricate optical devices for applications in sensing, imaging and communications. In this paper, we introduce hot stamping, a simple inexpensive and rapid technique to form 2D metallic patterns that are suitable for many terahertz devices. We fabricate several example devices to illustrate the versatility of the technique, including metasurfaces made of arrays of split-ring resonators with resonances up to 550 GHz. We also fabricate a wire-grid polarizer for use as a polarizing beam splitter. The simplicity and low cost of this technique can help in rapid prototyping and realization of future terahertz devices. 

Despite the rapidly growing interest in exploiting millimeter and terahertz waves for wireless data transfer, the role of reflected non-line-of-sight (NLOS) paths in wireless networking is one of the least explored questions. In this paper, we investigate the idea of harnessing these specular NLOS paths for communication in directional networks at frequencies above 100 GHz. We explore several illustrative transmitter architectures, namely, a conventional substrate-lens dipole antenna and a leaky-wave antenna. We investigate how these high-gain directional antennas offer both new challenges and new opportunities for exploiting NLOS paths. Our results demonstrate the sensitivity to antenna alignment, power spectrum variations, and the disparity in supported bandwidth of various line-of-sight (LOS) and reflected path configurations. We show that NLOS paths can, under certain circumstances, offer even higher data rates than the conventional LOS path. This result illustrates the unique opportunities that distinguish THz wireless systems from those that operate at lower frequencies. 

We demonstrate a 2D radar system for the THz region using a leaky parallel-plate waveguide, which can support real-time object tracking. The system can track a target within 200 ms with an accuracy of 1 mm in range and 1.4° in angle. Because the system is based on broadband excitation, it can locate multiple objects simultaneously. The broadband excitation also enables sensing of objects for which there is no direct line-of-sight path to the waveguide, via detection of a non-line-of-sight path.