Bio-inspired spatially variant photonic crystals for self-collimation and beam-steering applications in the near-infrared spectrum

Abstract

The self-collimation of light through Photonic Crystals (PCs) due to their optical properties and through a special geometric structure offers a new form of beam steering with highly optical control capabilities for a range of different applications. The objective of this work is to understand self-collimation and bending of light beams through bio-inspired Spatially Variant Photonic Crystals (SVPCs) made from dielectric materials such as silicon dioxide and common polymers used in three-dimensional printing like SU-8. Based upon natural PCs found in animals such as butterflies and fish, the PCs developed in this work can be used to manipulate different wavelengths of light for optical communications, multiplexing, and beam-tuning devices for light detection and ranging applications. In this paper, we show the optical properties and potential applications of two different SVPC designs that can control light through a 90-degree bend and optical logic gates. These two-dimensional SVPC designs were optimized for operation in the near-infrared range of approximately 800–1000 nm for the 90-degree bend and 700–1000 nm for the optical logic gate. These SVPCs were shown to provide high transmission through desired regions with low reflection and absorption of light to prove the potential benefits of these structures for future optical systems.

Development of spatially variant photonic crystals to control light in the near-infrared spectrum

“…A comparison between the experimental results and the various simulation models for the 2D and 3D simulations are shown in the Table 1 . Our results presented in prior published work using SU-8 10 , 14 are provided as well for additional perspective and validation of these results.…”

“…The initial approach to develop SVPCs follows a similar technique for Spatially Varying Lattices (SVL) 5 , 17 presented in prior work 10 , 14 . At subwavelength scales in the NIR, however, this model is inefficient due to its fragility, resolution requirements, and large computational time for printing and simulation.…”

“…The modeling approach builds upon prior work 10 , 14 ; however, the structure is simplified to make it more feasible for fabrication and implementation in specific devices. Instead of stretching or distorting each unit cell and corresponding holes, additional cells are added based on the layer distance in order to maintain the same spacing of holes and unit cells, preserving the bandgap and self-collimation properties of the PC as spatial variation is introduced.…”

“…One of these PC designs is a lattice structure composed of individual unit cells with carefully tailored fill fractions ( ff ), lattice constants, and sizes or scales 9 . The nano- and microscale geometries forming the uniform lattice allow unique optical properties to be developed such as tailored bandgaps that enable the structure to maintain the self-collimation of light as it propagates through the structure 5 , 10 , 11 .…”

“…This system can provide higher data transfer speeds using optical instead of electrical signals as well as smaller scale systems when compared to mirror or waveguide systems and operating through free space as opposed to optical fibers. Although we have presented our approach for simulating two-dimensional (2D) SVPCs in previous publications 10 , 14 , we seek to explore three-dimensional (3D) simulations in this paper and present initial validation of these designs through fabrication and laboratory experiments. This work shows the benefit and potential of SVPCs for applications in the NIR spectrum using low-refractive index materials.…”