Abstract-Strong optical reflection of rare-earth garnets in the terahertz regime by reststrahlen bands

Phys. Rev. B 89, 205124 – Published 23 May 2014

Masaki Adachi, Hiroyasu Yamahara, Shunsuke Kawabe, Hiroaki Matsui, and Hitoshi Tabata

The reststrahlen bands of rare-earth garnets were investigated in the terahertz regime. Through this, it was found that the crystal orientation and light polarization directly influence the reststrahlen-related dielectric absorptions of Gd3Ga5O12 (GGG), which is attributed to restriction in the vibrational motion of Gd ions. A theoretical fit to the dielectric absorption revealed that the phonon-polariton frequency in GGG crystals at around 85.5 cm−1 exhibits a narrow spectral width of 100 GHz at room temperature, as estimated using a Lorentz oscillator model. In addition, it was found that the reststrahlen bands can be readily manipulated within a range of 0.7–3.7 THz by changing the chemical composition of the garnet.

DOI: http://dx.doi.org/10.1103/PhysRevB.89.205124

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