Shaping of Optical Wavefronts Using Light‐Patterned Photothermal Metamaterial

Abstract

Having full control of light propagation in free space represents the ultimate goal for an imaging system. Spatial Light Modulators (SLMs), featuring the ability to actively control the spatial distribution of light components, are usually limited either to performing small and continuous adjustments to imaging aberrations or to rapidly shifting discrete segments of the wavefront with severe diffraction artifacts. Here a photothermally modulated optical structure is introduced as a highly responsive SLM capable of producing arbitrarily shaped wavefront patterns with smooth as well as step‐like features. The phase‐shift inducing temperature profile within the plasmonic metamaterial at the core of the SLM structure replicates closely the pattern of illuminating light intensity avoiding the common speed and spatial gradient limitations. As a result, the SLM concept is insensitive to polarization, free of diffraction artifacts, and offers sub‐millisecond response time and high transmittance >80%. The dynamic generation of a set of common optical functions is demonstrated, including low‐order Zernike polynomials patterns, phase grating, or vortex, which build an essential phase modulation toolbox across different imaging applications.