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Lossless Photon management – Optical design for manufacture at different length scales

Periodic Reporting for period 2 - NOLOSS (Lossless Photon management – Optical design for manufacture at different length scales)

Reporting period: 2018-04-01 to 2020-03-31

In the 21 century, optical technologies start to gather fruits for its long investment in research and development supported by technologies developed for microelectronics. The basic driver is miniaturization and with the maturity of micro- and nanofabrication tools even standard optical components like lenses will change their appearance. Especially the move from single components, to complete systems and their integral optimization will challenge the research and development activities and opens a disruptive pathway to optical component design and manufacture. Everything gets smaller, everything must interact perfectly, and everything should be designed together. If we look at technologies, what are the ongoing challenges? As mentioned optics uses many different techniques but with the same goal: achieving the optical quality of the components. The term “optical quality” stands for nanometer precision. For lenses, it means excellent surface definition and quality, but for nanostructured components, its definition becomes more complex and includes uniformity over surfaces of millimeter size. If we look at miniaturization in optics, we see several challenges.
Firstly, the optical elements need to be connected to the macroscopic world and will need to cover a certain surface or volume. High-quality production over millimeters for nanometer scale structures needs to be developed.
Secondly, to fully profit from the fine structure of the components one would like to change parameters of nanostructures locally. With mm size optical element and a 100 nm sized basic structural element, one ends up with more than 100 million elements. If only a few of them are used for the design of an optical function, then the parameters space for optimization will not be manageable with conventional design approaches. An optical multidimensional system design can handle many parameters and is based on a rigorous method which needs to become the standard. An optical design will become a big data problem.
A third challenge is the characterization at different lengths of scale. Often underestimated, is the link between the quality of nanostructures and its optical function, which is not easy to establish. The ultimate characterization technique would have a large field of view in the millimeter range – to see the whole element at once and still deliver nanometer resolution. But such techniques do not exist yet and would lead to data volumes for analyses that are not manageable by the existing informatics infrastructure. The optical characterization is already a big problem where data is concerned.
Our activities are based on experiences in the most modern fields of research in optics: nano-photonics including meta-surfaces and meta-materials, micro-optics referring to refractive and diffractive structures and system optics which takes up the different aspects of integrating such components. NOLOSS allows 15 fellows to pursue their PhDs in the industry in the framework of a European Indus- trial Doctorate (EID) Marie Curie Actions. With 12 participants, including nine partners from the industry, this allows us to widen the view of technology development at industrial partners, as they expand their network to SMEs that would not otherwise be possible.
This project is a training network. The fellows received intensive training in one general scientific training workshop (a second will follow in May 2018) and one research training workshop (the next will follow in October 2018).
Because of a close collaboration between academics and industry and common interests, the fellows very well receive the training, especially the training at industrial beneficiaries. For all of them working in a development and research department is an unmatched experience.
Several activities are launched forming teams and each of these activities is proposed and supervised by the industrial partners. On the academics side, research is done to provide deeper theoretical insight. We work in 3 technical work-packages on Nano-photonics, Micro-optics and system optics.
In the first half of the project fellows were hired, basic training was provide and the subjects were introduced. The majority of fellows started less than 18 months ago. At this stage they are becoming professionals in the field of research and start to create high-level results. This is visible in first publications and patents.
Main research training outcomes are determined by unique opportunities for fellows to conduct innovative research in the challenging technical problems with potential for broad technological impact. The research in nano-photonics and micro-optics carried out by the consortium is applied to a very diverse palette of multi-disciplinary industrially relevant applications, which belong to the core-businesses of the industrial partners.
For Nano-photonics, Important contributions to better and faster Simulation tools are expected from Xavier Garcia Santiago and Anton Pakhomov. Evgeniia Slivina’s project strives to evaluate the energy yield of solar modules at different locations and under various conditions , merging multiscale optical, energy, and electrical parameters’ simulations will allow for customization of the solar cell structures depending on geographic location. For Jonas Berzins further work considered polarization sensitivity of regular ordered nanostructures at surfaces, building a basis for spectro-polarimetric cameras and further improvement in the resolution of mask-aligner lithography is expected from the use of optical metasurfaces as mask structures by Andreas Vetter to help realizing such structures.
In Micro – optics the step to multidimensional problems will lead the project of Dong Cheon Kim far beyond the state of the art in diffractive optical design of today. Including a system aspect by considering source parameters in resoant domain micro optics design are the next steps for Maryam Yousefi. With the help of electromagnetic simulation software, Po-Ju Chen will develop robust simulation setting. Paolo Ansuinelli uses ptychography is a phase retrieval technique that enables the reconstruction of the complex transmission function of an object and electromagnetic simulation of metasurfaces is done by Kevin Müller who expects to find designs of metasurfaces that can be fabricated on large surfaces and which are competitive with other diffractive and refractive optical elements.
In system- optics projects on advanced imaging like lightfield cameras studied by Alessandro Grosso expects to improve the already existing plenoptic imaging techniques based on the use of microlens array (MLA). Similar resukts but with a different approach can be realized by different types of coded aperture will be studied by Po-Sheng Chiu. On the use ptychography, Xukang Wei will contribute to top notch research by testing a spatially partial coherent method and compare with experimental data. With the holographic lens design prepared by Jannik Trapp, he has progressed the state of the art by introducing volume holography into a field, in which only refractive solutions are known. Materials designed by Daniel Werdehausen will lead to refractive index values that can be specifically designed to applications not only in value but also in dispersion.
Image by Dong Cheon Kim