Characterization and application of dichroic filters in the 0.1-3-THz region

Low-loss dichroic filters, a subgroup of frequency-selective components, ha ve been characterized by terahertz time-domain spectroscopy in the region f rom 0.1 to 3 THz and with Fourier transform spectroscopy. The two data sets are fully consistent, The time-domain spectrometer is used to investigate the phase velocity behavior of dichroic filters. The dichroic filters have various applications in frequency mixing, multiplying, and diplexing experi ments. In a novel application, cascaded filters were used to limit the tera hertz pulse bandwidth and to monitor molecular transitions of atmospheric w ater vapor in a selected frequency band.