Abstract

Terahertz (THz) radiation is critical to the areas of security, medicine, communications, and consumer applications. THz generation is often achieved using lithium niobate, LiNbO₃, since it has a high nonlinear coefficient in this regime (d₃₃=180 pm/V [1]). Dramatic improvement to the generation efficiency has been achieved by incorporating this material into waveguiding configurations [2,3], since waveguides allow the pump pulse to remain confined over large distance (millimeters or longer). To date, waveguides investigated for THz generation utilize transverse core dimensions larger than a few microns. However, when the waveguide core is sub-wavelength with respect to the pump wavelengths, as well as the generated THz wavelengths, another benefit is observed: substantial broadening of the generated THz bandwidth. Here, we report on a sub-wavelength SiO₂-LiNbO₃-SiO₂ slab waveguide that produces wideband THz radiation and emits it in the form of Cherenkov waves.

© 2019 IEEE