Quasi-optical techniques

The basic theory of quasi-optical Gaussian beam propagation and beam transformation by simple optical elements is summarized, and coupling to and between Gaussian beams is briefly discussed. Guidelines for Gaussian optics system design are reviewed, the most important being beam truncation and matching. Passive components in the terahertz frequency range based on quasi-optical propagation, including polarization processors, filters, diplexers, and ferrite devices, are examined. Some active quasi-optical devices, including multielement oscillators, frequency multipliers, and phase shifters, are described. Some specific applications of quasi-optical systems are briefly described.>