Terahertz Polaritonics

Between electronics and photonics there exists a frequency gap of approximately two octaves, i.e., the frequency range between 100 GHz and 10 THz, across which there are limited capabilities for signal generation, control, guidance, and processing. Here, we demonstrate that phonon-polaritons in ionic crystals like LiNbO³ or LiTaO³ may be used to bridge this gap. The ability to directly visualize polariton fields through real-space imaging, to generate arbitrary THz waveforms through the use of temporally and/or spatially shaped optical waveforms, and to fabricate integrated functional elements for polariton guidance and control through laser machining yields a THz polaritonics platform that enables advanced signal processing and spectroscopy applications.