Work

Ion-beam-sputtered mid-infrared coatings for hybrid supermirrors

Year: 2025

Type: article

Abstract: 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-Si/SiO 2 DBR with an Al 2 O 3 bonding layer, and HR2, a six-period a-Si/Ta 2 O 5 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 ). NCAOBW 2041-1723 10.1038/s41467-023-43367-z

Source: Applied Optics

DOI: 10.1364/ao.575163

Authors: Lukas W. Perner, Valentin J. Wittwer, Gar-Wing Truong, Seth B. Cataño-Lopez, Garrett D. Cole, Thomas Südmeyer

Institutions: Thorlabs (Germany), Freedom Photonics (United States), University of Arizona

Language: English

Topic: Optical Coatings and Gratings

Subfield: Surfaces, Coatings and Films

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Funder: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung

Award: High Precision Optical Metrology of Mid-Infrared Coatings deposited by Ion Beam Sputtering (IBS)