Diffraction of Light from Optical Fourier Surfaces

TL;DR

This study experimentally investigates optical Fourier surfaces (OFSs), demonstrating their precise diffraction properties align with electrodynamic simulations, surpassing traditional scalar models, and highlighting their potential in advanced optical applications.

Contribution

The paper introduces a refined fabrication process for optical Fourier surfaces and provides the first experimental validation of their diffraction performance against electrodynamic simulations.

Findings

Measured optical responses match electrodynamic simulations.

Measurements diverge from traditional scalar diffraction models.

OF surfaces enable precise Fourier-spectrum engineering.

Abstract

Diffractive surfaces shape optical wavefronts for applications in spectroscopy, high-speed communication, and imaging. The performance of these structures is primarily determined by how precisely they can be patterned. Fabrication constraints commonly lead to square-shaped, "binary" profiles that contain unwanted spatial frequencies that contaminate the diffraction. Recently, "wavy" surfaces (known as optical Fourier surfaces, OFSs) have been introduced that include only the desired spatial frequencies. However, the optical performance and reliability of these structures have not yet been experimentally tested with respect to models and simulations. Such a quantitative investigation could also provide previously unobtainable information about the diffraction process from the most fundamental diffractive surfaces$\unicode{x2014}$sinusoidally pure profiles. Here, we produce and study two classes of reflective OFSs: (i) single-sinusoidal profiles of varying depth and (ii) double-sinusoidal profiles with varying relative phase. After refining our fabrication procedure to obtain larger and deeper OFSs at higher yields, we find that the measured optical responses from our OFSs agree quantitatively with full electrodynamic simulations. In contrast, our measurements diverge from analytical scalar diffraction models routinely used by researchers to describe diffraction. Overall, our results confirm that OFSs provide a precise and powerful platform for Fourier-spectrum engineering, satisfying the growing demand for intricately patterned interfaces for applications in holography, augmented reality, and optical computing.