Optical coatings deposited by reactive ion plating

TLDR

The study investigates how reactive ion‑plating parameters affect the transmittance and reflectance of single layers of HfO₂, Ta₂O₅, and SiO₂. The authors varied reactive ion‑plating conditions, measured laser‑damage thresholds at 1064 nm and 248 nm, and fabricated single‑ and double‑cavity filters for UV (< 1 nm) and near‑IR (50 nm) bandwidths. They report optical constants for the as‑deposited layers, find that post‑annealing at 375 °C shifts filter peak wavelengths and increases transmittance, and observe that ambient humidity has negligible effect on wavelength.

Abstract

The effect of different reactive ion-plating process parameters on the transmittance and the reflectance of single layers of HfO(2), Ta(2)O(5), and SiO(2) are investigated. The optical constants obtained for these three as-deposited materials are presented. Laser-damage threshold trends are examined on single- and double-layer coatings at 1064 nm and on high-reflectance coatings for 248 nm. Single- and double-cavity filters are constructed for the UV (< 1-nm bandwidth) and near-infrared (50-nm bandwidth) regions, respectively. After the filters are postannealed in air at 375 °C for several hours, a shift in the peak wavelengths is observed along with a substantial increase in the peak transmittance. As expected, no significant wavelength shifts result from changes in the humidity of the ambient atmosphere.