Environmental testing of high-quality Alexandrite crystals and coatings for space applications

Abstract

Despite the extensive studies of Alexandrite as a potential laser-active medium for future Earth observation space missions in the last years, the corresponding laser systems and especially coated Alexandrite crystals do not exceed Technology Readiness Level (TRL) 4. This means that although the developed Alexandrite-based laser systems have been validated in the laboratory, it has not been published up to now, whether they can withstand the harsh environmental conditions in space. In the course of the Horizon 2020 project GALACTIC, high-quality functionallycoated Alexandrite crystals developed and manufactured within the GALACTIC project will be qualified according to TRL 6 in an environmental test campaign comprising irradiation and thermal cycling tests together with optical performance tests before and afterwards (functional laser tests, LIDT, and transmission measurements). In this work, we present our strategy for testing functionally coated alexandrite crystals for space applications developed, fabricated and tested in a fully European supply chain within the GALACTIC project with the goal of increasing the TRL level to 6.