Phase noise mitigation of the microwave-tophotonic conversion process using feedback on the laser current

International audienceThe generation and transfer of ultra-stable microwave signals are of paramount importance in numerous applications spanning from radar systems to communications and metrology. We demonstrate residual phase noise mitigation at 10GHzof a directly modulated laser system through active control of the laser bias current. The latter is tuned to a finely selected point, where the current-to-phase dependence, measured at several microwave power and frequency values, is maximized. A residual phase noise of -113 dBrad2=Hz at 1 Hz offset frequency from a 10 GHz carrier, with a fractional frequency stability of 1.210 -16 at 1 s and below 10 -19 at 10 5 s, is measured. These performances are compliant with the transfer of the most stable microwave signals available to date, obtained with cryogenic sapphire oscillators or combs locked tocavity-stabilized lasers. This approach is of interest for the distribution of ultra-stable microwave signals in a very simple photonic configuration