Computer-generated stratified diffractive optical elements

Abstract

We present what is to our knowledge a new type of diffractive optical element (DOE), the computer-generated stratified diffractive optical element (SDOE), a hybridization of thin computer-generated DOEs and volume holograms. A model and several algorithms for calculating computer-generated SDOEs are given. Simulations and experimental results are presented that exhibit the properties of computer-generated SDOEs: the strong angular and wavelength selectivity of SDOEs makes it possible to store multiple pages in a computer-generated SDOE, which can be read out separately (multiplexing). The reconstruction of an optimized SDOE has a higher quality than the reconstruction of optimized one-layer DOEs. SDOEs can be calculated to have only one diffraction order.

Comparison of different simulation methods for multiplane computer generated holograms

“…4, [3,4]). The result of the design algorithm are required fields u el,l (x) that have to be realized by the height structures.…”

“…1). With this concept it is for example possible to achieve higher diffraction efficiencies in the case of gratings [1,2], the multiplexing of several pages of information into one CGH [3], the creation of color images [4] or the combination of several different optical functionalities [5]. The reaction of a multi plane setup to a change in any setup parameter (like illumination wavelength, illumination direction, distance between the planes, refractive index) is a lot more complex than in the single plane case.…”

“…The most common one is the iterative Fourier transform algorithm (IFTA). A method that extends these algorithm to more than one plane while maintaining its original flexibility is described in [3,4]. It allows to encode multiple arbitrary pages of information into a multi plane CGH.…”

Cascaded diffractive optical elements for improved multiplane image reconstruction

“…Diffraction properties of stratified volume holographic optical elements have been researched and, for example, the angular selectivity of such devices has been demonstrated as a function of buffer layer parameters [3]. Several works have examined angular and wavelength selectivity with possible practical applications for iteratively designed multiple CGH planes in a cascaded setup [4][5][6]. In addition, a general design procedure has been proposed, and some multiplexing characteristics have been shown, for classes of volumetric optical devices [7,8].…”

Azimuthal multiplexing 3D diffractive optics

“…Further, new insight in wave manipulation and the ever-increasing power of computers enable diffractive optics to generate user-defined wavefronts from arbitrary inputs, by virtue of degrees of freedom from pixels that can be addressed individually and independently 9-11 . Beyond classical applications such as beam shaping 12,13 , 3D display 14,15 , information security 16,17 , spectroscopy 18 , metrology 19 , and astronomical imaging 20 , emerging areas include optical tweezers 21,22 , novel microscopies 23,24 , coherent control 25,26 , quantum information 27,28 , neural networks 29,30 , and optogenetics 31,32 .Three dimensional (3D) diffractive optics expand the capabilities of traditional two-dimensional elements not only by providing higher diffraction efficiency and higher information capacity, but also enabling functionalities such as multiplexing and space-variant functions [33][34][35] . The capability of controlling multidimensional spatial, spectral, temporal, and coherence functions of light fields is originated from the multi-subject nature of 3D diffractive optics involving diffraction, refraction, absorption, resonances, and scattering.In spite of being a topic of great interest, 3D diffractive optics have not been fully investigated due to their physical and mathematical complexity, where the challenge stems from three aspects: First, the wavefront propagation must obey Maxwell's equations, while most arbitrary target patterns do not, causing the problem to be inconsistent.…”