Progress toward an efficient, uniformly scalable lithium niobate terahertz pulse source

We report significant progress in developing a compact, imaging-free, and scalable tilted-pulse-front-pumped (TPFP) terahertz (THz) source based on a nonlinear echelon slab. The slab thickness- and pump intensity-dependent THz generation efficiency have been characterized, reaching an efficiency of ∼0.085%, which is ∼2.8× higher than previously. The impact of microstructure quality shows that surface roughness reduces efficiency by lowering diffraction efficiency and increasing beam divergence. A simple theoretical model is introduced, which shows good agreement with experimental results and predicts significantly higher efficiency-exceeding 0.65% (2%) at room (cryogenic) temperature-with refined microstructure quality.