Ultra-broadband mid-infrared generation in dispersion-engineered thin-film lithium niobate
Jatadhari Mishra, Marc Jankowski, Alexander Y. Hwang, Hubert S. Stokowski, Timothy P. McKenna, Carsten Langrock, Edwin Ng, David Heydari, Hideo Mabuchi, Amir H. Safavi‐Naeini, M. M. Fejer
Abstract
Thin-film lithium niobate (TFLN) is an emerging platform for compact, low-power nonlinear-optical devices, and has been used extensively for near-infrared frequency conversion. Recent work has extended these devices to mid-infrared wavelengths, where broadly tunable sources may be used for chemical sensing. To this end, we demonstrate efficient and broadband difference frequency generation between a fixed 1-µm pump and a tunable telecom source in uniformly-poled TFLN-on-sapphire by harnessing the dispersion-engineering available in tightly-confining waveguides. We show a simultaneous 1-2 order-of-magnitude improvement in conversion efficiency and ∼5-fold enhancement of operating bandwidth for mid-infrared generation when compared to equal-length conventional lithium niobate waveguides. We also examine the effects of mid-infrared loss from surface-adsorbed water on the performance of these devices.