Spherical rubidium vapor cells fabricated by micro glass blowing

This paper presents an application of micro glass blowing, in which multiple glass spheres are simultaneously shaped on top of a silicon wafer and subsequently filled with rubidium. The fabrication process is based on etching cavities in silicon, followed by anodic bonding of a thin glass wafer to the etched silicon wafer. The bonded wafers are then heated inside a furnace at a temperature above the softening point of the glass, and due to expansion of the heated trapped gas in the cavities, the glass is blown into three-dimensional spherical cells. Microscopic alkali vapor cells are achieved by evaporation of ⁸⁷Rb through a small glass nozzle into the cell cavities. The cells are then sealed by anodic bonding. The results of the cell fabrication and characterization are presented.