Differentiable wave propagation method for shape optimization of freeform optics beyond the paraxial approximation
Year: 2025
Type: article
Abstract: Freeform optics provides precise control of light for beam shaping and mode conversion, but designing volumetric micro-optical elements requires efficient, low-runtime simulation methods. The wave propagation method (WPM) offers a fast alternative to full-wave solvers for high-index-contrast and non-paraxial systems but lacks differentiability, preventing its use with gradient descent methods for inverse design. We propose a differentiable formulation of WPM using smoothstep functions to create a soft partition of the spatial domain, allowing for gradient-based optimization. This crucial modification enables a general and computationally efficient framework for solving inverse design problems in micro-optics. We demonstrate its effectiveness through the simulation of a freeform hologram exhibiting high diffraction angles, highlighting the limitations of traditional paraxial methods.
Source: Optics Letters
DOI: 10.1364/ol.559067
Authors: Nicolas Barré, Marc Brunel
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4408885699