The ever-growing demand for submicrometer-structured
surfaces with
hierarchical features is guided by efficient applications in augmented/virtual
reality, display technologies, and Fourier optics, as well as for
the development of multifunctional platforms for biomedicine, sensors,
and security. Among all, Fourier surfaces still represent a challenge.
Indeed, the current technologies are mainly based on multistep processes
which involve lithographic methods and/or thermal/chemical/electrical
treatment and often suffer in terms of losses due to their intrinsic
binary design. Herein, a broadband laser composed of close and highly
correlated lines allows for the simultaneous photoinscription of extremely
precise hierarchical Fourier surfaces via vectorial
interference. By simply setting the number of lines, their amplitude,
and polarization, the polychromatic light enables a high-fidelity
encoding of multiple sinusoidal profiles with nanometric spatial resolution.
Beat phenomena that arise in the bulk of the recording medium result
in the never-observed hierarchical structuring of the topography.
Such an approach, unconventional for holographic techniques where
monochromaticity of light is a key element, provides promising perspectives
for the in situ design of hierarchical Fourier surfaces
and the scale-up of customized structured platforms, besides the obvious
advantages of the method in terms of scalability, reconfigurability,
and tunability.