High yield atomic vapor cell manufacturing and packaging for atomic clocks and magnetometers

OUSD (R&E) MODERNIZATION PRIORITY: Quantum Science TECHNOLOGY AREA(S): Sensors, Electronics and Electronic Warfare; Materials / Processes OBJECTIVE: Develop a manufacturing process which allows greater yield (>80%) per wafer batch on vapor cell wafer runs to support quantum clocks and magnetometers. DESCRIPTION: Over the last decade, quantum sensor technology (including atomic clocks and atomic magnetometers) have accelerated in performance to provide new and important capabilities for the DoD. While the performance of these quantum devices has improved significantly, the ability to deploy them for DoD missions is still lacking due to inadequate processing and manufacturing capabilities, specifically at capacities needed to meet the SWaP-C requirements for DoD deployable systems. One area of improvement lies at the heart of these quantum devices - the atomic vapor cell. Even with commercialized atomic clocks and magnetometers, manufacturing techniques to fabricate vapor cells and thermal packages have proved elusive, often resulting in low yield and considerable added expense to the device. The fabrication of these vapor cells typically requires high heat and high voltage in a process called anodic bonding which complicates the manufacturing process and leads to inconsistency in the final product. We are seeking a microfabrication technique for parallel, batch manufacturing of vapor cells that does not rely on anodic bonding for the final seal. The technology should be capable of scaling to high volumes with production yields that exceed 80 percent and a path towards producing hundreds of thousands of vapor cells per year. Proposing companies should also include compact packaging techniques that provide thermal stability and power reduction. These advances will allow for quantum devices to be produced at significantly lower cost, with the goal to achieve significantly wider dissemination across the DoD. We are looking for vapor cell manufacturing and packaging technologies that accelerate manufacturing, produce greater quantity per batch, provide reduced part-to-part variation (greater consistency), improve SWAP (size, weight, and power), and provide overall cost reductions for quantum sensors like atomic clocks and atomic magnetometers. PHASE I: A successful Phase I will demonstrate the production of vapor cells with yield greater than 70 percent on a substrate having a cavity array of 5x5 and using a non-anodic bonding technique. The cells must demonstrate a judicious proportion of alkali gas, buffer gas, and leak proof vapor cell manufacturing. A design for packaging the cells should also be included. PHASE II: Phase II will advance the phase I techniques to successfully demonstrate manufacturing runs on a full wafer-scale substrate while achieving a production yield that exceeds 80 percent. The packaging solution should be demonstrated in a prototype device. A sample of vapor cells should be substantiated by using them to demonstrate either an atomic clock or an atomic magnetometer. PHASE III DUAL USE APPLICATIONS: Commercial applications include smaller, more affordable atomic clocks for use in navigation and enhanced cellular timing holdover, and magnetometers for geological surveying and mineral prospecting. DoD applications involving magnetometers like magnetic anomaly detection can benefit from inexpensive sensors that are low enough powered to fly on small UAS. REFERENCES: S. Knappe, V. Gerginov, P. D.D. Schwindt, V. Shah, H. G. Robinson, L. Hollberg, and J. Kitching, "Atomic vapor cells for chip-scale atomic clocks with improved long-term frequency stability," Opt. Lett. 30, 2351-2353 (2005). Yanjun Zhang, Yunchao Li, Xuwen Hu, Lu Zhang, Zhaojun Liu, Kaifang Zhang, Shihao Mou, Shougang Zhang, and Shubin Yan, "Micro-fabrication process of vapor cells for chip-scale atomic clocks," Chin. Opt. Lett. 17, 040202- (2019). John Kitching , "Chip-scale atomic devices", Applied Physics Reviews 5, 031302 (2018) https://doi.org/10.1063/1.5026238. KEYWORDS: Vapor Cell Manufacturing; Atomic Clocks; Atomic Magnetometer; high Yield