Shaping LED Beams with Radially Distributed Waveguide‐Encoded Lattices

Abstract

AbstractSlim, flexible polymer films imprinted with a radial distribution of cylindrical waveguides precisely control the shape and trajectory of light emitting diode (LED) beams. These radially distributed waveguide‐encoded lattices (RDWEL) are generated when a large, converging population comprising thousands of self‐trapped incandescent beams induces the corresponding array of waveguides in a photopolymerizable fluid. The waveguides are multimoded and impart a seamless field of view (FOV) of 70°, an enhancement of 320%, to the polymer film. A divergent LED beam incident on the plane‐faced RDWEL efficiently couples into its constituent waveguides and, depending on their orientation, is either focused or increases in divergence. In the RDWELDIV configuration, where waveguides diverge along the propagation axis, the LED beam suffers a 45% increase in divergence. When the same film is flipped to the RDWELCONV geometry, where waveguides converge along the propagation axis, the beam focuses to an effective focal length of ≈2 mm. These findings represent a new approach based on wave‐guided beam steering to precisely tailor LED beams. By changing parameters such as the FOV, lattice geometry, refractive index contrast, it would be possible to systematically tailor the shape and propagation of LED beams. This is not possible with existing technologies.