An iodine-based ultra-stable optical frequency reference and its application in fundamental physics space missions

We present the development of compact and ruggedized iodine-based frequency references on elegant breadboard (EBB) and engineering model (EM) level using modulation transfer spectroscopy near 532 nm. A frequency stabilty of 1·10
^-14
at an integration time of 1 s and below 5·10
^-15
at integration times between 10s and 100s was achieved. Space applications of such an optical frequency reference can be found in fundamental physics, geoscience, Earth observation, navigation and ranging. One example is the proposed mSTAR (mini SpaceTime Asymmetry Research) mission, dedicated to perform a Kennedy-Thorndike experiment on a satellite in a low-Earth orbit. By comparing an iodine standard to a cavity-based frequency reference and integration over 2 year mission lifetime, the Kennedy-Thorndike coefficient will be determined with up to two orders of magnitude higher accuracy than the current best ground experiment.