A frequency standard for ytterbium (Yb)-doped fiber lasers and application towards the cold atomic experiments using a rubidium (Rb) two-photon transition

We characterize a two-photon transition (TPT) of rubidium (Rb) atoms from the ground state (5$S_{1/2}$) to the excited state (4$D_{5/2}$), using a ytterbium (Yb)-doped fiber amplifier at 1033 nm. This is the first demonstration, according to our knowledge, of a one colour two-photon transition for the above energy levels. A simple, cost-effective laser locking technique at 1033 nm is demonstrated, exploiting the above TPT fluorescence spectroscopy. This technique has potential applications in the fiber laser industry as a frequency standard, particularly for the Yb-doped fiber lasers. This TPT also has applications in atomic physics as a background-free high-resolution atom detection and for quantum communication, which is outlined in this paper.