Impact of the slit geometry on the performance of wire-grid polarisers

TL;DR

This paper investigates how the geometry of slit structures affects wire-grid polariser performance, revealing that fabrication details significantly influence the discrepancy between predicted and actual extinction ratios, and proposing a new model for optimization.

Contribution

It introduces a detailed comparison between theory and experiment, accounting for fabrication details, and develops a new optimization model for improved polariser performance.

Findings

Discrepancies are due to true plasmonic structure shapes.

A new optimization model aligns theory with experimental results.

Achieved extinction ratios above 1,000 at 850 nm.

Abstract

Wire-grid polarisers are versatile and scalable components which can be engineered to achieve small sizes and extremely high extinction ratios. Yet the measured performances are always significantly below the predicted values obtained from numerical simulations. Here we report on a detailed comparison between theoretical and experimental performances. We show that the discrepancy can be explained by the true shape of the plasmonic structures. Taking into account the fabrication details, a new optimisation model enables us to achieve excellent agreement with the observed response and to re-optimise the grating parameters to ensure experimental extinction ratios well above 1,000 at 850 nm.