Spatially addressable design of gradient index structures through spatial light modulator based holographic lithography

Abstract

In this paper, we present an achievable gradient refractive index in bi-continuous holographic structures that are formed through five-beam interference. We further present a theoretic approach for the realization of gradient index devices by engineering the phases of the interfering beams with a pixelated spatial light modulator. As an example, the design concept of a gradient index Luneburg lens is verified through full-wave electromagnetic simulations. These five beams with desired phases can be generated through programming gray level super-cells in a diffractive spatial light modulator. As a proof-of-concept, gradient index structures are demonstrated using synthesized and gradient phase patterns displayed in the spatial light modulator.

Optical induction of non-diffracting discrete photonic lattice

“…Thus far, some techniques have been proposed and developed for making periodic optical microstructures, such as self-assembly, twophoton absorption, colloidal crystallization and holographic lithography [10][11][12][13][14][15]. Recent years, the optical induction technology [3][4][5][6], was reported and has drawn much attention.…”

“…Conventional multiple beams interference is implemented by a complicated optical setup. In [15], Matoba et al fabricated 2D waveguide arrays using the Mach-Zehnder configuration with piezoelectric translator. In [6], Zhang et al fabricated 3D photonic lattices using superposition of a pair of 2D photonic lattices by two amplitude masks.…”

Spatial light modulator based holographic fabrication of 3D spatially varying photonic crystal templates

“…27 Setups incorporating spatial light modulators present new opportunities to fabricate many of the same structures as traditional holographic lithography setups by generating the appropriate intensity profiles using computer generated holograms. [28][29][30][31][32][33][34][35][36][37][38]41 Computer generated holograms on phase-only SLMs have proven effective in generating multi-beam interferences, which are capable of fabricating periodic, [29][30][31][32][33] quasi-periodic structures, 28 and chiral photonic crystals. 31 By incorporating higher Fourier order into the phase pattern in conjunction with an amplitude SLM, multiperiodic lattices can be formed.…”

“…37 Through pixel-by-pixel phase engineering of a simple synthesized phase pattern, simple spatially varying wave fields can be produced. 38 Recently, a hexagonal lattice wave field was produced with a gradient basis, allowing potential single step holographic fabrication of gradient index photonic crystals. 39 With the recent development of a novel method of calculating the structure of functionally graded photonic lattices with spatially varying lattice orientation, spacing, and filling fraction, 40 selfcollimating photonic crystals capable of bending light around a 90° bend are possible, and have been fabricated using 3D printing.…”

Optical generation of a spatially variant two-dimensional lattice structure by using a phase only spatial light modulator

“…A single step, low cost, large area fabrication of periodic (or quasi periodic) photonic crystal structures is possible by the method of interference lithography 5,6 and few recent advances with phase only spatial light modulator (SLM) assisted interference lithography has enabled the fabrication of some unconventional photonic crystal structures. These structures include embedding of defect sites [7][8][9] , creation of line defects 10 , dual lattice structures 11 and gradient structures 12,13 . This approach is better than other fabrication approaches like e-beam lithography 14 or direct laser writing 15 because they being serial in nature are prone to errors and are time consuming.…”