Optical Frequency References for Space Applications

Abstract

High-performance optical frequency references are required by a multitude of future space missions. These includes missions in Earth observation, fundamental physics and navigation and ranging. They are used as frequency-stable light source for high-sensitivity laser interferometry and as part of an optical clock with high stability and accuracy. Different method for laser frequency stabilization are conceivable, where stabilization to an atomic or molecular transition yields an absolute frequency reference with high long-term stability. We present the current status of iodine-based frequency references where several compact setups for space applications have been realized in the past. Applications of these references in space-based tests of special relativity and in future GNSS are highlighted.