Mid-infrared spectroscopy with a broadly tunable thin-film lithium niobate optical parametric oscillator
Alexander Y. Hwang, Hubert S. Stokowski, Tae‐Won Park, Marc Jankowski, Timothy P. McKenna, Carsten Langrock, Jatadhari Mishra, Vahid Ansari, M. M. Fejer, Amir H. Safavi‐Naeini
Abstract
Mid-infrared spectroscopy, an important technique for sensing molecules, has encountered barriers from sources either limited in tuning range or excessively bulky for widespread use. We present a compact, efficient, and broadly tunable optical parametric oscillator surmounting these challenges. Leveraging dispersion-engineered thin-film lithium niobate-on-sapphire photonics and a singly resonant cavity allows broad, controlled tuning over an octave from 1.5–3.3 µm. The device generates >25mW of mid-infrared light at 3.2 µm with 15% conversion efficiency. The ability to precisely control the device’s mid-infrared emission enables spectroscopy of methane and ammonia, demonstrating our approach’s relevance for sensing. Our work signifies an important advance in nonlinear photonics miniaturization, bringing practical field applications of high-speed, broadband mid-infrared spectroscopy closer to reality.