Degradation of Ta2O5 / SiO2 dielectric cavity mirrors in ultra-high vacuum
Abstract
In order for optical cavities to enable strong light-matter interactions for quantum metrology, networking, and scalability in quantum computing systems, their mirrors must have minimal losses. However, high-finesse dielectric cavity mirrors can degrade in ultra-high vacuum (UHV), increasing the challenges of upgrading to cavity-coupled quantum systems. We observe the optical degradation of high-finesse dielectric optical cavity mirrors after high-temperature UHV bake in the form of a substantial increase in surface roughness. We provide an explanation of the degradation through atomic force microscopy (AFM), X-ray fluorescence (XRF), selective wet etching, and optical measurements. We find the degradation is explained by oxygen reduction in Ta2O5 followed by growth of tantalum sub-oxide defects with height to width aspect ratios near ten. We discuss the dependence of mirror loss on surface roughness and finally give recommendations to avoid degradation to allow for quick adoption of cavity-coupled systems.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 07, 2023
- Source ID
- 10.1364/oe.504858
Entities
People
- Alan Schwartzman
- Alyssa Rudelis
- Beili Hu
- Edita Bytyqi
- Josiah Sinclair
- Monika Schleier-Smith
- Roberto Brenes
- Tamar Kadosh Zhitomirsky
- Vladan Vuletić
Organizations
- Army Research Office
- Massachusetts Institute of Technology
- National Science Foundation
- Office of Science
- Stanford University
- United States Department of Energy