Preventing and reversing vacuum-induced optical losses in high-finesse tantalum (V) oxide mirror coatings
High-finesse optical cavities placed under vacuum are foundational platforms in quantum information science with photons and atoms. We study the vacuum-induced degradation of high-finesse optical cavities with mirror coatings composed of SiO[subscript 2]-Ta[subscript 2]O[subscript 5] dielectric stac...
| Main Authors: | , , , , , , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Optical Society of America
2015
|
| Online Access: | http://hdl.handle.net/1721.1/99933 https://orcid.org/0000-0001-7296-523X https://orcid.org/0000-0002-7054-2310 https://orcid.org/0000-0001-8586-4999 https://orcid.org/0000-0001-5193-2711 https://orcid.org/0000-0002-9786-0538 https://orcid.org/0000-0001-6155-9463 https://orcid.org/0000-0001-8276-8256 https://orcid.org/0000-0002-8069-8327 https://orcid.org/0000-0002-7100-0847 |
| Summary: | High-finesse optical cavities placed under vacuum are foundational platforms in quantum information science with photons and atoms. We study the vacuum-induced degradation of high-finesse optical cavities with mirror coatings composed of SiO[subscript 2]-Ta[subscript 2]O[subscript 5] dielectric stacks, and present methods to protect these coatings and to recover their initial low loss levels. For separate coatings with reflectivities centered at 370 nm and 422 nm, a vacuum-induced continuous increase in optical loss occurs if the surface-layer coating is made of Ta[subscript 2]O[subscript 5], while it does not occur if it is made of SiO[subscript 2]. The incurred optical loss can be reversed by filling the vacuum chamber with oxygen at atmospheric pressure, and the recovery rate can be strongly accelerated by continuous laser illumination at 422 nm. Both the degradation and the recovery processes depend strongly on temperature. We find that a 1 nm-thick layer of SiO[subscript 2] passivating the Ta[subscript 2]O[subscript 5] surface layer is sufficient to reduce the degradation rate by more than a factor of 10, strongly supporting surface oxygen depletion as the primary degradation mechanism. |
|---|