Doctoral thesis (Dissertations and theses)
First-Principles High-Throughput Study of Linear and Nonlinear Optical Materials
Naccarato, Francesco
2019
 

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Keywords :
Nonlinear Optics; First-Principles; High-Throughput
Abstract :
[en] Nonlinear optical (NLO) processes, such as second harmonic generation (SHG), play an important role in modern optics, especially in laser-related science and technology. They are at the core of a wide variety of applications ranging from optoelectronics to medicine. Among the various NLO materials, insulators are particularly important for second-order NLO properties. In particular, only crystals which are non-centrosymmetric can display a non-zero second-order NLO susceptibility. However, given the large number of requirements that a material needs to meet in order to be a good nonlinear optical material, the choice of compounds is drastically limited. Indeed, despite recent progress, a systematic approach to design NLO materials is still lacking. In this work, we conduct a first-principles high-throughput study on a large set of semiconductors for which we computed the linear and nonlinear susceptibility using Density Functional Perturbation Theory. For the linear optical properties, our calculations confirm the general trend that the refractive index is roughly inversely proportional to the band gap. In order to explain the large spread in the data distribution, we have found that two descriptors successfully describe materials with relatively high refraction index: (i) a narrow distribution in energy of the optical transitions which brings the average optical gap close to the direct band gap (ii) a large number of transitions around the band edge and/or high dipole matrix elements. For non-centrosymmetric crystals, we perform the calculation of the efficiency of SHG. We observe some materials with particularly high SHG, much stronger than the general relation with the linear refraction index through Miller’s rule predicts. We relate the value of Miller’s coefficient to geometric factors, i.e., how strongly the crystal deviates from a centrosymmetric one. We also identified interesting materials that show high optical responses for which it would be worth performing further analysis.
Disciplines :
Physics
Author, co-author :
Naccarato, Francesco ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Language :
English
Title :
First-Principles High-Throughput Study of Linear and Nonlinear Optical Materials
Defense date :
30 August 2019
Institution :
Unilu - University of Luxembourg, Luxembourg, Luxembourg
Université Ctholique de Louvain, Louvain-la-Neuve, Belgium
Degree :
Docteur De l'Université du Luxembourg en Physique
Promotor :
Wirtz, Ludger 
Rignanese, Gian-Marco
Secretary :
Gonze, Xavier
Jury member :
Botti, Silvana
Venkatraman, Gopalan
Focus Area :
Physics and Materials Science
European Projects :
H2020 - 641640 - EJD-FunMat - European Joint Doctorate in Functional Materials Research
Funders :
EJD-FunMat European Joint Doctorate in Functional Materials Research
CE - Commission Européenne [BE]
Available on ORBilu :
since 21 October 2019

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