Glass-blown spherical microcells for chip-scale atomic devices

This paper demonstrates spherical vapor cells intended to be used in chip-scale atomic devices. A micro glass blowing process is introduced, in which multiple glass spheres are simultaneously shaped on the top of a silicon wafer and subsequently filled with rubidium. In the presented fabrication process, an array of cylindrical cavities is first etched in silicon. Next, a thin glass wafer is anodically bonded to the silicon wafer. The bonded wafers are then placed inside a furnace set to 850 °C. At this elevated temperature, the viscosity of the glass is decreased and the heated trapped gas in the cavities expands, thus causing the glass to be blown into spherical cells. Microscopic alkali vapor cells are achieved by evaporation of Rb87 through a small glass nozzle into the cell cavities. The cells are then sealed by anodic bonding. The fabricated cells are characterized and the presence of rubidium vapor inside the cells is verified by observing an absorption spectrum.