Transmission features of frequency-selective components in the far infrared determined by terahertz time-domain spectroscopy

Transmission and phase-shift characteristics of dichroic high-pass filters with cutoff frequencies as high as 1.11 THz and of a cross-shaped grid band pass filter with a resonance frequency of 280 GHz were measured with an ele ctro-optic sampling terahertz time-domain spectrometer operating between 0. 1 and 2 THz. Good agreement with transmission theories is found. We also co mpare the transmission performance of cascaded dichroic filters with that o f cross-shaped grid bandpass filters. Both types of bandpass filter permit frequency-selective ultrafast experiments in the far-infrared spectral regi on. In the millimeter and the submillimeter wavelength regions, which are d ifficult to access by conventional means, knowledge of the frequency respon se of frequency-selective components is important for applications in frequ ency mixing, multiplying, and multiplexing in quasi-optical systems. (C) 19 99 Optical Society of America.