A scanning fabry perot cavity for the study of terahertz frequency polaritons

Abstract

The incorporation of spin dynamics into electronic and optical devices is a promising avenue of technological advancement. This work describes the development of a scanning Fabry-Perot cavity to study magnon-photon with terahertz (THz) light and its application to the measurement of a multiferroic antiferromagnet, Bismuth orthoferrite. The mirrors of this cavity are distributed Bragg reflectors made with alternating layers of silicon and air capable of creating a high reflection, low loss, low transmission for frequencies near 0.555 THz. Resonant frequencies of the cavity are moved across a THz spectral range of 0.5-0.6 THz allowing a search for hybridized magnon photon modes called cavity magnon polaritons (CMPs) (cavity modes coupled with electromagnon modes) in bismuth orthoferrite. Bismuth orthoferrite has known electromagnon modes in the THz region at 0.530 and 0.555 THz. The Fabry-Perot cavity is inserted into a tilted pulse front THz spectrometer and THz time-domain spectroscopy measurements are performed on the suspended Bismuth orthoferrite powder. Resonant frequency peak splitting near 0.530 THz and 0.555 THz is investigated.