  We present an innovative fiber laser system for both cesium and rubidium
manipulation. The architecture is based on frequency conversion of two lasers
at 1560 nm and 1878 nm. By taking advantage of existing fiber components at
these wavelengths, we demonstrate an all fiber laser system delivering 350 mW
at 780 nm for rubidium and 210 mW at 852 nm for cesium. This result highlights
the promising nature of such laser system especially for Cs manipulation for
which no fiber laser system has been reported. It offers new perspectives for
the development of atomic instruments dedicated to onboard applications and
opens the way to a new generation of atom interferometers involving three
atomic species $^{85}$Rb, $^{87}$Rb and $^{133}$Cs for which we propose an
original laser architecture.
