The Microfabricated Alkali Vapor Cell with High Hermeticity for Chip-Scale Atomic Clock

Shuo Jia,Jifeng Qu,Yijie Pan,Zhiyuan Jiang,Binbin Jiao,Xiaochi Liu,Zhenfei Song

doi:10.3390/app12010436

Abstract

Herein, a microfabricated millimeter-level vapor alkali cell with a high hermeticity is fabricated through a wet etching and single-chip anodic bonding process. The vapor cell, containing Rb and N2, was investigated in a coherent population trapping (CPT) setup for the application of a chip-scale atomic clock (CSAC). The contrast of CPT resonance is up to 1.1% within the only 1 mm length of light interacting with atom. The effects of some critical external parameters on the CPT resonance, such as laser intensity, cell temperature, and buffer gas pressure, are thoroughly studied and optimized. The improved microfabricated vapor cell also exhibited great potential for other chip-scale atomic devices.

Highlights

The interaction between light and atoms in the vapor phase has become a valuable tool for precision measurement
The microfabricated cell containing Rb and 70 torr nitrogen was heated to 90 ◦ C to ensure the sufficient density of the atoms, and the absorption spectroscopy of the reference cell was measured at ambient temperature
This paper presents a fast and flexible way of fabricating MEMS cells through improved MEMS technology and anodic bonding

Summary

Introduction

The interaction between light and atoms in the vapor phase has become a valuable tool for precision measurement Many physical quantities, such as frequency, temperature, and magnetic field, can be precisely determined based on the simple and well-defined quantum systems in atoms. Vapor cell atomic clocks are under development in labs around the world, reaching rather high levels of frequency stability [1]. The chip-scale atomic clock (CSAC), combing atomic spectroscopy, silicon micromachining, and semiconductor laser technology, brings the atomic frequency standard with a high performance out of the lab and directly to the users. Hermetic MEMS cells with optimal external parameters are still strongly needed in order to achieve a reliable commercial chip scale atomic device [17,18]. The impacts on the CPT resonance of some critical external parameters, such as laser intensity, cell temperature, and microwave power, were studied and determined

Fabrication and Setup

Results and Discussion

Conclusions