A novel technique for microfabricating alkali atom vapor cells is described in which alkali atoms are evaporated into a micromachined cell cavity through a glass nozzle. A cell of interior volume 1 mm³, containing ^87 Rb and a buffer gas, was made in this way and integrated into an atomic clock based on coherent population trapping. A fractional frequency instability of 6×10^−12 at 1000 s of integration was measured. The long-term drift of the F = 1, m_F = 0 --> F = 2, m_F = 0 hyperfine frequency of atoms in these cells is below 5×10^−11/day.
© 2005 Optical Society of America
S. Knappe, V. Gerginov, P. D. D. Schwindt, V. Shah, H. G. Robinson, L. Hollberg, and J. Kitching, "Atomic vapor cells for chip-scale atomic clocks with improved long-term frequency stability," Opt. Lett. 30, 2351-2353 (2005)