Metasurface array for single-shot spectroscopic ellipsometry

TL;DR

This paper introduces a compact metasurface array system for single-shot spectroscopic ellipsometry, enabling real-time, high-accuracy measurement of thin film properties without mechanical parts.

Contribution

The authors develop a silicon-based metasurface array that reconstructs the polarization spectrum in a single shot, replacing bulky traditional ellipsometers with a compact, robust device.

Findings

Achieved high-fidelity reconstruction of the Stokes polarization spectrum.

Demonstrated accurate determination of thin film thickness and refractive index.

Enabled real-time spectroscopic ellipsometry without mechanical movement.

Abstract

Spectroscopic ellipsometry is a potent method that is widely adopted for the measurement of thin film thickness and refractive index. However, a conventional ellipsometer, which utilizes a mechanically rotating polarizer and grating-based spectrometer for spectropolarimetric detection, is bulky, complex, and does not allow real-time measurements. Here, we demonstrated a compact metasurface array-based spectroscopic ellipsometry system that allows single-shot spectropolarimetric detection and accurate determination of thin film properties without any mechanical movement. The silicon-based metasurface array with a highly anisotropic and diverse spectral response is combined with iterative optimization to reconstruct the full Stokes polarization spectrum of the light reflected by the thin film with high fidelity. Subsequently, the film thickness and refractive index can be determined by fitting the measurement results to a proper material model with high accuracy. Our approach opens up a new pathway towards a compact and robust spectroscopic ellipsometry system for the high throughput measurement of thin film properties.