Improvements in the power level of sources near 1550 nm and in the efficiency of waveguide frequency doublers enabled us to lock a frequency-doubled source directly to the 5<i>S</i><sub>1/2</sub> → 5<i>D</i><sub>5/2</sub> two-photon transitions near 778 nm. We obtained a sufficiently powerful second-harmonic signal, exceeding 2 mW, by doubling an external-cavity diode laser that was amplified by an erbium-doped fiber amplifier in a periodically poled LiNbO<sub>3</sub> channel waveguide. Our experimental scheme can be used for realizing compact, high-performance frequency standards near 1550 nm for fiber-optic communication and sensing applications.
© 2000 Optical Society of America
A. Danielli, P. Rusian, A. Arie, M. H. Chou, and M. M. Fejer, "Frequency stabilization of a frequency-doubled 1556-nm source to the 5S1/2 → 5D 5/2 two-photon transitions of rubidium," Opt. Lett. 25, 905-907 (2000)