High damage threshold HfO₂/SiO₂ multilayer mirrors deposited by novel remote plasma sputtering

Abstract

Sputtering deposition coatings offer significant advantages on electron beam (EB) deposition, including high packing density, environmental stability and extremely low losses. But the inherent high compressive stress affects its application in high power laser system. This paper describes the technical feasibility of high damage threshold laser mirrors deposited by a novel remote plasma sputtering technique. This technique is based on generating intensive plasma remotely from the target and then magnetically steering the plasma to the target to realize the full uniform sputtering. The pseudo-independence between target voltage and target current provides us very flexible parameters tuning, especially for the films stress control. Deposition conditions are optimized to yield fully oxidized and low compressive stress single layer HfO₂ and SiO₂. The high damage threshold of 43.8 J/cm² for HfO₂/SiO₂ laser mirrors at 1064 nm is obtained. For the first time the remote plasma sputtering is successfully applied in depositing laser mirrors with high performance.

Keywords

Damage Threshold / Damage Morphology / Remote Plasma / High Damage Threshold / Laser Mirror

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