Fig. 1. Image of chip-sized alkali atom vapor cells.

Fig. 2. (Color online) The preparation process of MEMS atom vapor cell.

Fig. 3. (Color online) Schematic diagram of the absorption spectrum testing system. Optical beams are shown in red lines. Electrical connections are shown in blue lines. Light source; C, chopper; L1, collimating lens; L2, focusing lens; S, Sample; L3, focusing lens; A1, entrance slit; Monochromator; A2, exit slit; PD, detector; Lock-in amplifier; Computer.

Fig. 4. (Color online) Energy level spectrum of the Rb atom.

Fig. 5. (Color online) Absorption spectra of alkali atom vapor cells at different temperatures. (a) The atom vapor cell with 4 mm diameter cavity. (b) The atom vapor cell with 5 mm diameter cavity. (c) The atom vapor cell with 6 mm diameter cavity.

Fig. 6. (Color online) The relationship between the intensities of the two absorption peaks of the alkali atom vapor cells and the silicon cavity diameters. The heating temperatures of the alkali atom vapor cells are (a) 100 °C, (b) 120 °C, (c) 130 °C, (d) 140 °C.

Fig. 7. (Color online) Comparison of the absorption spectra of the alkali atom vapor cells with RbN₃ filling amounts of 125, 250, 375 and 500μg in the silicon cavities. The heating temperatures of the alkali atom vapor cells are (a) 110 °C, (b) 120 °C, (c) 130 °C, (d) 140 °C.