A Slim Polymer Film with a Seamless Panoramic Field of View: The Radially Distributed Waveguide Encoded Lattice (RDWEL)

Abstract

are not limited by the paraxial operation of classical thin lenses, also offer entirely new opportunities to image wide angular spaces. [21,22] Artificial compound eyes are however predominantly curved or hemispherical constructs including microlens arrays interfaced to photodetectors, [7,16] and elastomeric hemispheres patterned with lenses. [6,[23][24][25] While the fabrication of these architectures typically involves multiple steps and components, soft, single-component eyes have also been generated [26,27] or proposed [28,29] by inducing lens-capped waveguides in UV-polymerizable resins in 2D [26] and 3D [27,28] geometries.Inspired by the collective behavior of ommatidia, we are developing new classes of multifunctional polymer films, which are inscribed with dense arrays or lattices of cylindrical waveguides. [30] In striking contrast to the predominantly hemispherical architectures of natural and artificial compound eyes, these waveguide encoded lattices (WELs) are flexible, slim (≤3 mm), and optically flat, which provides ease of integration into existing light-based technologies such as solar cells, cameras, and smart screens. In addition, distinct from known examples of natural or artificial eyes, WELs also possess translational symmetry, which affords the scalability that is necessary for manufacturing (e.g., roll-to-roll) processes. We generate WELs through a single-step, room-temperature technique that employs large ensembles of nonlinear self-trapped filaments of visible light elicited in photopolymerizable media to permanently inscribe arrays of multimode, polychromatic waveguides. [31][32][33][34] We previously fabricated a WEL consisting of a thin, epoxide film embedded with pentadirectional, intersecting arrays of multimode cylindrical waveguides, which conferred an FOV of 94°, which represented a 66% enhancement relative to an unstructured film. The FOV of this structure corresponded to the sum of the angular acceptance ranges of waveguide arrays oriented along five discrete angles. Significantly, there was no overlap between these five ranges and the consequent discontinuities-or gaps-in the FOV prevented cross-talk between nonparallel waveguides. This, in turn, enabled sophisticated imaging functions such as panoramic imaging, inversion, and focusing that would normally require bulky optics. [30] We now report a WEL that possesses a seamless and significantly enhanced panoramic FOV of 115°, which originatesThe nearly hemispherical field of view (FOV) of arthropodal compound eyes has inspired analogs ranging from curved, lens-patterned domes to planar constructs patterned with microlenses. A radial distribution of cylindrical waveguides that monotonically spans ±33° confers an FOV of 115° to a slim (≤3 mm) polymer film. This is the greatest panoramic FOV reported for any plane-faced, single-component structure. The radially distributed waveguide encoded lattice (RDWEL) waveguides are inscribed in a single, room-temperature step by a large (≈15 000 cm −2 ), converging population of self-trapped...

Shaping LED Beams with Radially Distributed Waveguide‐Encoded Lattices

“…Figure a is a scheme of the optical assembly employed to fabricate the RDWEL . Here, a collimated broad white incandescent beam is first focused by a cylindrical condenser lens (f. l. = 12.8 mm) and then patterned by an amplitude mask (thickness = 1.75 mm) before being launched into an optically flat, transparent cell (pathlength = 2 mm) containing photopolymerizable acrylate fluid.…”

“…This generates a cylindrical waveguide, which entraps the bright spot and guides it as optical modes through the medium without diverging. In this way, the self‐trapped beams simultaneously inscribe the RDWEL—radial arrays of waveguides ( xz plane) that are periodically stacked along the y axis—within the acrylate film (Figure b).…”

“…Here we show that LED beams can be modulated by a single component, plane‐faced, slim polymer film embedded with a radial distribution of cylindrical waveguides. The radially distributed waveguide‐encoded lattice (RDWEL) is slim (≤2 mm) and flexible, rendering it suitable as a conformal coating that both protects and optically manipulates LED emission. Importantly, such coatings could be integrated without significantly disrupting mature LED fabrication technologies.…”

“…Importantly, such coatings could be integrated without significantly disrupting mature LED fabrication technologies. The RDWEL is fabricated through a single‐step, room‐temperature self‐inscription method developed in our group, which exploits the spontaneous self‐trapping of large populations of incandescent beams in photopolymerizable acrylate and epoxide fluids. Each self‐trapped beam elicited in these systems inscribes a multimoded, cylindrical waveguide capable of guiding all visible wavelengths of light.…”

“…Akin to the arthropodal compound eye, the RDWEL possesses an enhanced and seamless field of view (FOV) . As a result, a noncollimated LED beam incident on the RDWEL spontaneously partitions into the waveguide array and in this way, is guided without divergence as optical modes through the medium.…”