Abstract-Prism coupling of high-Q terahertz whispering-gallery-modes over two octaves from 0.2 THz to 1.1 THz

Dominik Walter Vogt, Angus Harvey Jones, Harald G. L. Schwefel, and Rainer Leonhardt

Fig. 1 (a) Schematic of the CW THz spectroscopy system with fiber coupled photo-conductive antennas (PCAs) using two-inch diameter s-p THz lenses to focus the THz radiation onto the base of the HRFZ-Si prism. The length of the base of the prism is about 13 mm. The spherical HRFZ-Si WGMR is mounted on a 3D manual translation stage, and the position is observed using two microscope cameras. (b) and (c) show the corresponding top and side view, respectively, of the 8 mm HRFZ-Si sphere next to the HRFZ-Si prism. Please note that (c) is focused on the prism surface.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-24-31190

We report on prism coupling of high-quality (high-Q) terahertz (THz) whispering-gallery modes (WGMs) in spherical high resistivity float zone grown silicon (HRFZ-Si) resonators over two octaves from 0.2 THz to 1.1 THz. The WGMs are excited using a HRFZ-Si prism and show unprecedented quality factors of up to 2.2 × 104. A detailed discussion of the phase-and mode-matching criteria of the prism coupling scheme implemented in the continuous wave THz spectroscopy system is presented. The results provide numerous op

portunities for passive ultra-broadband high-Q devices operating in the THz frequency range.

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