title: Observation of rubidium 5S1/2 --> 7S1/2 two-photon transitions with a diode laser.
abstract: The 5S1/2 --> 7S1/2 two-photon transition of atomic rubidium, which is 100 times weaker than the 5S-5D transition, is observed with an extended-cavity diode laser and a vapor cell. Signals with a signal-to-noise ratio of 280 are obtained with a laser power of 10 mW, and the observed linewidth is 3 MHz. The laser wavelength is 760 nm and is locked on the transitions to a stability of 2 x 10(-11). For the first time to our knowledge, the isotope shift of this transition is measured to be 130(4) MHz in atomic frequency.
authors.affiliation: Department of Physics, National Tsing Hau University, Hsinchu 300, Taiwan.
authors.forename: Ming-Sheng
authors.initials: MS
authors.lastname: Ko
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Liu