Millimeter-Wave and THz-Wave Visualization

This chapter describes the principles of a self-heterodyne and nonpolarimetric frequency down-conversion techniques, and introduces several visualization systems based on these techniques. The visualization technique described here is based on photonics technology, and it demonstrates visualization in the range of 1–600 GHz with the identical system configuration and electro-optic (EO) probes. In addition, using frequency/phase noise cancellation technique together with the nonpolarimetric frequency down-conversion technique, it is possible to visualize the field distribution of the electric field emitted from a self-oscillating device and frequency-modulated continuous wave (FMCW) signal. This chapter also shows various visualization examples in the microwave, millimeter-wave, and terahertz (THz)-wave regions. The visualization example in the microwave region (1–10 GHz) shows the spatial distribution of the electric field between the signal line and the ground plane of the microstrip line. As the examples in the millimeter-wave region, the visualizations of the electric field scattered by a rough metal surface, 77 GHz electric field transmitted through a car bumper, and FMCW signals are presented. Finally, the demonstrations in the THz band includes the visualizations of the radiation field from a broadband optical-to-electrical (O/E) converter (120–600 GHz), wavefront transformation by metal hole array (MHA), modification of the beam shape by a self-healing beam during propagation, and propagation of a pulse train with a center frequency of 120 GHz and a repetition rate of 10 GHz.