Wafer-Level Micro Alkali Vapor Cells with Anti-Relaxation Coating Compatible with MEMS Packaging for Chip-Scale Atomic Magnetometers

Abstract

Compared with superconducting quantuminterference devices, chip-scale atomic magnetometersusing the wafer-level micro alkali vapor cells can be usedmore conveniently in the applications of geophysicalmapping, health care and remote monitoring. Drasticwall collisions and decreased polarization lifetime arethe main barriers for the performance of the chip-scaleatomic magnetometers. In this study, OTS organic filmscoated on the inner surface of the micro vapor cells wereused to suppress wall collisions and improve polarizationlifetime of the alkali atoms in the micro cells. First of all, the fabrication process of wafer-level micro OTS coatedvapor cells is introduced, the process is based on anodicbonding technology. Then the prepared wafer-levelmicro OTS coated vapor cells have been characterizedby the water-contact angle test and measured in themicro-machined spin-exchange relaxation free(SERF) atomic magnetometers. Results show that the OTScoating is effective after anodic bonding from the watercontactangle test. Results also indicate that the spinexchange relaxation free atomic magnetometer using themicro OTS-coated vapor cell can operate successfully.