Designing a Hexagonal Array of Gradient Pitch Helix Structure using Multiple Beam Interference for Broadband Light Trapping

We present a single-step fabrication approach of gradient pitch helix (GPH) structures arranged in a hexagonal array over a large area. In this simulation work, the structure has been generated by the mutual interference of seven beams where six beams are arranged symmetrically in a conical geometry. Another beam is along the central axis of the cone. This mechanism is a phase-controlled interference where each beam is assigned a distinct phase value. All the six beams have plane wavefronts, whereas the central beam is with a spherical wavefront. The numerical analysis theoretically demonstrates that the structure embedded in an active medium leads to light trapping and enhanced absorption for energy harvesting.