2021/10/30 by Dingding Ren, Ren, Dingding, Chao Dong +3
Engineering · Physics and Astronomy · #Advanced Fiber Laser Technologies #Applied Physics (physics.app-ph) #FOS: Physical sciences #Mechanical and Optical Resonators #Optics (physics.optics) #Photonic and Optical Devices
paper · pdf · doi:10.48550/arxiv.2111.00362
openalex publication_date 2021/10/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The longwave infrared (LWIR) region of the spectrum spans 8 to 14 μm and enables high-performance sensing and imaging for detection, ranging, and monitoring. Chip-scale integrated LWIR photonics has enormous potential for real-time environmental monitoring, explosive detection, and biomedicine. However, realizing advanced technologies such as precision sensors and broadband frequency combs requires ultra low-loss components, which have so far remained elusive in this regime. We demonstrate that non-epitaxial germanium is an enabling technology for longwave infrared integrated photonics, using it to demonstrate the first high quality (Q) factor whispering gallery mode microresonators in the LWIR, which we couple to integrated low-loss waveguides. At 8 μm, we measure losses of 0.5 dB/cm and intrinsic Q factors of 2.5x105, nearly two orders of magnitude higher than prior LWIR resonators. Our work portends the development of integrated sensing and nonlinear photonics in the LWIR regime.