Wafer-Level Hermetic All-Glass Packaging for Microalkali Vapor Cells of Chip-Scale Atomic Devices

To maintain a controllable environment for microalkali vapor cells of high-performance chip-scale atomic devices, a novel wafer-level hermetic all-glass packaging technology for microalkali vapor cells of atomic devices was investigated. A glass wafer with metal vias was used as the substrate to host the miroalkali vapor cells. Wafer-level hemispherical glass bubbles prepared by a chemical foaming process were used as transparent packaging caps. The performance of the rubidium vapor cell in the all-glass hermetic package was characterized by a laser frequency locking system and an ultraviolet spectrophotometer. The results show that hermetic all-glass packaging at a wafer level was demonstrated successfully. The results also indicate that after the hermetic all-glass packaging, the temperature variation of the microalkali vapor cells was controllably below 0.2°C at different working temperatures of atomic devices. A chip-scale atomic magnetometer using the hermetic all-glass micro vapor cell was demonstrated eventually.