Mots clefs : métrologie des temps-fréquences, étalon de fréquence optique, spectroscopie de très haute résolution, mesure absolue de fréquence optique, Strontium, refroidissement laser, atomes froids, laser semi-conducteur, doublage de fréquence, ralentisseur Zeeman, piège magnéto-optique, réseau optique, régime de Lamb-Dicke.
This PhD thesis presents the contributions to the building of a new optical lattice clock with trapped Strontium atoms. After reviewing in the introduction the working basis principles and the aims of atomic frequency standards, and also the state of the art on optical clocks, we firstly stress on the concept of optical lattice clock with trapped neutral Strontium atoms as it is already implemented in a first apparatus at LNE-SYRTE. Then we expose the experimental results that we have obtained with it during our last spectroscopy campaign in the beginning of my PhD on the fermion 87Sr. Put into perspective with the ultimate expected performances, this frequency evaluation with an accuracy that reaches 2,6×10-15 lead us to justify our motivations to build a new independent Strontium optical lattice clock. The three following parts focus on giving the details about the different stages of ther realization of this new clock, thereby insisting on the improvements we have brought towards the first one. We start with the setting up of the new vacuum chamber where the atomic beam is successively ejected out of the oven, deflected, slowed down and then captured into a magneto-optical trap. The deflection stage constitutes a new implementation that participates to the improvement of the clock performances ; it has been at first numerically simulated and then experimentally checked. Afterwards we describe the optical lattice where the atoms are transferred and dipole trapped. We show the efficient trapping of the atoms that we have achieved with only semiconducting laser sources, on condition that wedecrease the parametric heating effects by stabilizing upstream the frequency noise of the source. At the end of the thesis we have successively cooled down the atoms, interrogated them with a new ultrastable laser, detected the clock transition probability and finally observed first atomic resonance signals. First series of camparisons between both Strontium clocks concludes this work.
Keywords : time & frequency metrology, optical frequency standard, high resolution spectroscopy, absolute optical frequency measurement, Strontium, laser cooling, cold atoms, semiconductor laser, frequency doubling, Zeeman slower, magneto-optical trap, optical lattice, Lamb-Dicke regime.