High Fidelity Vectorial Holography via Broadband Laser: Towards a Scale-up of Ultra-compact

There is an ever-growing demand for ultra-compact optical elements due to their all-optical light structuring and polarization control, and their efficient application in augmented/ virtual reality, displays technologies, Fourier optics, and photonics [1]. Thanks to their ultra-flat design and sub-wavelength control tremendous interest is currently devoted to platforms based on metamaterials [2]. However, these a priori designed systems suffer in terms of reconfigurability, and tunability as well as complex and multi-step fabrication processes which may limit their potential as full-scale technology [3]. Herein, multiplexed and cross-talk-free holograms, with nanometric separation and independent functionalities in light control, are encoded in a single-step process via broadband vectorial interferometry. The key point is the use of a single laser source operating in multiline mode which allows for the simultaneous holographic patterning by a polychromatic beam composed of multiple, highly correlated, and extremely close lines (Figure 1). Such multiwavelength light, unconventional for holographic encoding, unlocks new features of organized collective phenomena in photoresponsive soft-materials, able to overcome usual spatial resolution limitations. The flexibility of the approach gives promising perspectives for reconfigurable, tunable, and in-situ design of ultra-compact optical elements, besides the obvious advantages of the method in easiness, scalability, cost effectiveness, and time and energy consuming [4]. Figure 1: Sketch of the Broadband vectorial holography set-up. An Ar+ laser beam is firstly directed through broadband optical elements (BOEs) to independently set the intensities and the polarization state of the various lines. Subsequently, it is divided by a non-polarizing beam splitter (BS) cube into two beams with equal intensity which are then directed, via a couple of mirrors, on the sample. The two polychromatic beams generate the Mj light patterns (PP, OC, OL) at the overlapping position. REFERENCES 1. Dorrah, A. H., et al., "Tunable structured light with flat optics," Science, Vol. 376, No. 367, 2022. 2. Shaltout, A. M., et al., "Spatiotemporal light control with active metasurfaces," Science, Vol. 364, No. 648, 2019. 3. Arbabi, A., et al., "Fundamental limits of ultrathin metasurfaces," Scientific Reports, Vol. 7, No. 43722, 2017. 4. Audia, B., et al., "Multi-wavelength optical patterning for multiscale materials design," Photonics, Vol. 8, No. 481, 1-9, 2021.