Massachusetts Institute of Technology researchers in Cambridge have fabricated solid-state platforms in crystalline structures that can generate and propagate terahertz polaritons. They are conducting further experiments to better characterize the polaritonic waveguide modes and loss characteristics in the structures.

As described in the October issue of Nature Materials, the scientists machined the micron-scale features in 0.2-mm-thick LiTaO₃ and 0.5-mm-thick LiNbO₃ crystals using approximately 100-µJ pulses from a Ti:sapphire laser. They generated phonon-polariton "ripples" in the structures with amplified femtosecond pulses polarized parallel to the crystals' axes with impulsive stimulated Raman scattering. The researchers demonstrated a 90° turn of a polariton ripple in a structure comprising two waveguides and a reflecting face, as well as a structure that splits the ripple into two signals and recombines them interferometrically.