OPTICAL TECHNOLOGIES AS A PERSPECTIVE FOR FUTURE GNSS

Optical frequency references are a key element for the realization of future space missions. They are needed for missions related to tests of fundamental physics, gravitational wave detection, Earth observation and navigation and ranging. In missions such as GRACE follow-on or LISA the optical frequency reference is used as light source for high-sensitivity inter-satellite distance metrology. While cavity-based systems are current baseline e.g. for LISA, frequency stabilization on a hyper�ne transition in molecular iodine near 532nm is a promising alternative. Due to its absolute frequency, iodine standards crucially simplify the initial spacecraft acquisition procedures. Current setups ful�ll the GRACE-FO and LISA frequency stability requirements and are realized near Engineering Model level. We present the current status of our developments on Elegant Breadboard (EBB) and Engineering Model (EM) level taking into account speci�c design criteria for space compatibility such as compactness (size iodine spectroscopy EM: 38 � 18 � 10 cm3) and robustness. Both setups achieved similar frequency stabilities of � 1�1