An erbium-doped fiber optical frequency comb

In a joint GSTP research effort between Germany and France a radiation tolerant Erbium-doped fiber optical frequency comb has been developed and verified. Named ERDURAC, the achievement represents a cornerstone for the future application of frequency comb technologies in space, enabling various quantum optics applications for navigation, gravimetry, Earth observation and ranging in future missions.

The frequency comb tolerated radiation to one 1 kilogray (a measure of absorbed radiation) at a dose rate of 10 milligray/s, without significant degradation of its operability and signal strength. This is roughly what the comb would experience in terms of radiation if it was operating in a mid-Earth orbit for 10 years. Specialty doped fibers were developed by iXblue and the subsequent design for the fiber optical combs was manufactured by Menlo Systems.

The comb’s fiber verification has been achieved using both passive and active fiber laser arrangements investigated under gamma irradiation. The final radiation hardness qualification took place at the calibrated Cobalt60 source located at ESA’s ESTEC facilities. 

Next, the comb will be launched to the Bartolomeo platform where the frequency comb will be used to compare the stability of two iodine stabilised reference lasers with ground based precision optical references via a bidirectional laser link.