Ion-beam-sputtered mid-infrared coatings for hybrid supermirrors
We report on the development of low-loss ion-beam-sputtered (IBS) mid-infrared coatings for hybrid supermirrors. Two highly reflective designs were realized: HR1, a four-period a-<i>S</i><i>i</i>/<i>S</i><i>i</i><i>O</i><sub>2</sub> DBR with an <i>A</i><i>l</i><sub>2</sub><i>O</i><sub>3</sub> bonding layer, and HR2, a six-period a-<i>S</i><i>i</i>/<i>T</i><i>a</i><sub>2</sub><i>O</i><sub>5</sub> DBR with an a-Si terminating layer for bonding. Combined with a GaAs/AlGaAs crystalline mirror, HR2-based hybrids yielded a total loss of 9.3 ppm and excess loss of 6.8 ppm at 4.45 µm, with cavity finesse up to 396,000. We used IBS-deposited a-Si directly as a bonding layer, for the first time, to our knowledge, verified its sub-angstrom roughness, and demonstrated excellent optical performance. This establishes a clear path toward scalable coatings for longer mid-infrared wavelengths, building on prior results in Nat. Commun.14, 7846 (2023).NCAOBW2041-172310.1038/s41467-023-43367-z.
Authors
- Thomas Südmeyer (ORCID: https://orcid.org/0000-0002-2425-1846)
- Seth B. Cataño-Lopez (ORCID: https://orcid.org/0000-0002-2857-1847)
- Garrett D. Cole (ORCID: https://orcid.org/0000-0001-7149-3218)
- Lukas W. Perner (ORCID: https://orcid.org/0000-0001-8872-2072)
- Gar-Wing Truong (ORCID: https://orcid.org/0000-0002-3112-5717)
- Valentin Johannes Wittwer (ORCID: https://orcid.org/0000-0003-1883-2393)
Institutions
- Thorlabs (Germany) (DE)
- University of Arizona (US)
- Freedom Photonics (United States) (US)
Publication Details
- Journal
- Applied Optics
- Published
- 2025-11-25
- DOI
- https://doi.org/10.1364/ao.575163
- Primary Topic
- Optical Coatings and Gratings
- Type
- article
- Field-Weighted Citation Impact
- 0.00