Work package leader: Dr Rodolphe Le Targat, LNE, OBSPARIS Other participants: KU, LUH, NPL, PTB, TUBITAK, VTT ULE cavity from LUH A key factor in the performance of optical clocks is the spectral purity of the clock laser probing the narrow atomic transition. The aim of this work package is therefore to develop a new generation of stable lasers, along with strategies to transfer the stability into wavelengths necessary for clock operation and to deliver the stability to the atoms. The target is to achieve laser frequency instabilities at or below the 1 × 10-16 level after one second. Advanced techniques will be developed to tackle the factors presently limiting ultrastable cavities: the thermal noise and the vibration noise. The transfer of spectral purity via femtosecond frequency combs will also be investigated, in order to demonstrate that a stability level of 10-17 after one second can be transferred to metrologically relevant wavelengths. Aditionally, exploratory novel techniques including spectral hole burning and active resonators will be studied in order to assess their reliability and potential for use in optical clocks in the future.
