During the first period of the project, the fellow carried out chemical synthesis of nanoparticles and assemblies of nanoparticles from different material composition, but the helical structures made up of semiconductor quantum dots which were already designed in the group (results also published in 2017, few months before the start date of the project) were found to be promising because of their nonlinear optical properties. More specifically, it was found that these helices exhibit second-harmonic generation (SHG), a feature of nonlinear optics. This result raised many more interesting questions about the origin of this SHG. It was found that this direction was promising and worth deeper investigation. In this aspect, measurements were done using microscopes within the facilities of the University of Michigan. A two-photon microscope located within the Microscopy Center was extensively used. The fellow spent his last 7 months at the University to collect microscopic images, optimize sample and imaging conditions and calibrate the apparatus for power measurements. Quantitative measurements were also obtained from power measurements. However, it was found that spectroscopic measurements were needed to supplement the data. In this context, a collaboration started with the group of Prof. Valev in the University of Bath (U.K). Prof. Valev is a specialist in nonlinear optics and focused on nonlinear chiroptical activity over the past 10 years. His group developed a setup that would allow spectroscopic data combined with microscopic data as well. At the end of the first period at the University of Michigan, the fellow sent samples to collaborators in U.K (University of Bath, group of Prof. Valev).
