# Monolayer Metasurface Enabling Linear Polarizer and Quarter-Wave Plate for Chip-Scale Atomic Clocks

## TL;DR

A new monolayer metasurface enables precise polarization control for chip-scale atomic clocks, improving their performance and miniaturization.

## Contribution

The work introduces a metasurface that simultaneously controls polarization and balances optical power for chip-scale atomic clocks.

## Key findings

- The metasurface converts linear to circular polarization with a PER of 4.8 dB and DOP of 74.2%.
- The CSAC prototype achieves a frequency stability of 9.29 × 10−11 at 1 s and 1.59 × 10−11 at 10,000 s.
- The design integrates polarization control and optical power balancing in a single layer for CSACs.

## Abstract

A monolayer metasurface-based Linear Polarizer and Quarter-Wave Plate (LP&QWP) is proposed for compact and precise polarization control in chip-scale atomic clocks (CSACs). Finite-difference time-domain simulations reveal that the designed metasurface efficiently converts linearly polarized light into right-handed circularly polarized light. Experimental characterization of devices fabricated on optical glass substrates confirms the polarization manipulation performance, achieving a polarization extinction ratio (PER) of 4.8 dB and a degree of polarization (DOP) of 74.2%, confirming its ability to effectively control the state of polarization. The short-term frequency stability of the developed CSAC prototype reaches 9.29 × 10−11 at 1 s and 1.59 × 10−11 at 10,000 s, demonstrating its potential for integration into miniature timing systems. The novelty of this work lies in the specific application to CSACs and the co-optimization with attenuation, as the metasurface simultaneously realizes polarization control and optical power balancing within a single functional layer. This study bridges metasurface photonics and atomic frequency standards, providing a functional route toward polarization control and frequency stability in miniaturized chip-scale atomic clocks.