Optical Fourier Surfaces for Holography

Controlling light is crucial for modern technologies, such as solar cells, biosensors, and optical communication. A common approach involves the fabrication of nanostructured surfaces with sub-wavelength feature sizes to manipulate electromagnetic fields through diffraction. However, current lithographic methods are typically restricted to “binary” surface profiles with only two depth levels, limiting their optical performance. Here, we overcome this limitation by exploiting thermal scanning-probe lithography to fabricate grayscale diffractive surfaces, known as optical Fourier surfaces (OFSs) [1]. We utilize these OFSs as reflective phase-only holograms in silver to control the amplitude and phase of the diffracted wavefront in the far field. Due to the non-trivial relation between the surface profile and diffraction output [2], an adapted Gerchberg–Saxton algorithm [3] is applied to inversely design the OFS holograms. Furthermore, we extend the concept of OFS holograms to diffract bound electromagnetic modes, such as surface-plasmon polaritons [4] and waveguided photons [5], to free space. This approach may provide expanded possibilities for holography, beam shaping, and optical display technology.<br/><br/><b>References:</b><br/>[1] Lassaline, N. et al. Optical Fourier surfaces. <i>Nature</i> <b>582</b>, 506–510 (2020).<br/>[2] Harvey, J. E. & Pfisterer, R. N. Understanding diffraction grating behavior, part II: parametric diffraction efficiency of sinusoidal reflection (holographic) gratings. <i>Opt. Eng.</i> <b>59,</b> 017103 (2020).<br/>[3] Gerchberg, R. W. & Saxton, W. O. A practical algorithm for the determination of the phase from image and diffraction plane pictures. <i>Optik</i> <b>35</b>, 237–246 (1972).<br/>[4] Dolev, I., Epstein, I. & Arie, A. Surface-plasmon holographic beam shaping. <i>Phys. Rev. Lett.</i> <b>109</b>, 203903 (2012).<br/>[5] Huang, Z. Q., Marks, D. L. & Smith, D. R. Out-of-plane computer-generated multicolor waveguide holography, <i>Optica</i> <b>6</b>, 119–124 (2019).