GALACTIC mission to establish supply chain for alexandrite laser crystals

15 May 2023

Horizon 2020 project partners include LZH, Optomaterials, and Altechna; applications in space communications.

In the European Horizon 2020 project GALACTIC, the partners Laser Zentrum Hannover (LZH), Optomaterials S.r.l. (Milan, Italy), and Altechna (Vilnius, Lithuania), have succeeded in establishing a solely European supply chain for alexandrite laser crystals, which can be used for space applications.

Optomaterials produces competitive crystals, which Altechna provides with a special coating. To achieve the necessary properties for space-applications, Altechna has developed special coating designs and processes based on ion beam and magnetron sputtering processes.

Scientists at the LZH then tested the crystals in dedicated laser systems. They designed these systems with future applications in mind. They say that the crystal demonstrators “could lay the foundation for new laser-based measuring instruments”.

The LZH’s scientists exposed the Alexandrite crystals to proton and gamma radiation and ran them through several temperature cycles typical of space applications. Before and after these environmental tests, the LZH team characterized the crystals in terms of their transmission properties and laser performance, among other things.

Since the environmental tests did not significantly change the measured parameters, the space suitability was demonstrated, stated LZH. In addition, the researchers showed that the laser-induced damage threshold of the crystals is equal to – or even exceeds – leading products on the world market.

They comment that the crystals are “now ready for the market”. GALACTIC’s technology readiness level has been elevated to TRL 6 – which was previously at 4 for these products.

Special properties

Alexandrite crystals have good thermal conductivity and fracture strength. Therefore, they are suitable for use in high power laser systems and are robust enough to withstand the harsh conditions in space.

Since the crystals can be used to tune the output wavelength of laser systems, they could form the basis of new types of laser-based measuring instruments for Earth observation satellites. Such instruments could be used to collect more precise climate-relevant data on the state of the atmosphere or vegetation.

The GALACTIC project was funded by the European Union’s Horizon 2020 research and innovation program and coordinated by the LZH. The first publication of GALACTIC’s results are contained in the Optics Express paper (2023) High-performance cavity-dumped Q-switched Alexandrite laser CW diode-pumped in double-pass configuration (2023).