Uniformly scalable lithium niobate THz pulse source in transmission geometry

Abstract

A novel THz source, based on optical rectification in LiNbO3 using the tilted-pulse-front technique, is proposed and experimentally demonstrated. The pulse-front tilt is introduced by a volume phase holographic grating, efficiently used at perpendicular incidence in transmission, and the THz pulses are produced in a LiNbO3 plane-parallel nonlinear echelon slab, arranged parallel to the grating. As a unique feature, the entire setup has a plane-parallel, transmission-type configuration, which straightforwardly enables distortion-free scaling to large sizes, high pulse energies and high THz field strengths. The possibility of operating the setup at cryogenic temperature for increased THz generation efficiency is also investigated. Calculations predict efficiencies of 95% for diffraction and 2% for THz generation at room temperature with a refractive-index-matching liquid between the grating and the echelon slab.

Tilted pulse front pumping techniques for efficient terahertz pulse generation

“…In the case of plane parallel NLES, the imaging can also be omitted by using volume holographic gratings 85 , hence they provide more than 90% diffraction efficiency even if they are not in Littrow configuration 86 , 87 .…”

“…Certainly, the novel TPFP THz source configurations introduced in the preceding chapter can also be implemented with semiconductors, offering even easier feasibility due to the reduced tilt angle requirement 65 , 80 – 85 , 88 , 89 . For example, by implementing a contact grating arrangement with a ZnTe nonlinear crystal as shown in Fig.…”