The doctoral dissertation in the field of Photonics will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus.
What is the topic of your doctoral research? Why is it important to study the topic?
The topic of my doctoral research is engineering coherence of light with nanostructures. Coherence is a fundamental property of light, and understanding it is essential in many applications, such as biomedical imaging, astronomy, and free space optical telecommunications. Modern nanofabrication methods have allowed researchers to engineer nano- and micrometer scale optical structures in the lab for controlling the properties of light. My research introduces novel approaches for tailoring optical coherence using nanostructures, with implications for future photonic technologies.
What are the key findings or observations of your doctoral research?
The key findings of my research include the demonstration of a novel metasurface based optical system capable of generating partially coherent light beams, realization of a layered epsilon-near-zero structure that exhibits pronounced polarization- and angle-dependent reflectance, paving the way for novel laser designs, and the investigation of the coherence properties and temporal dynamics of lasing in plasmonic nanoparticle arrays, contributing to the understanding of nanoscale light sources and their potential for ultrafast photonic devices.
How can the results of your doctoral research be utilised in practice?
The layered epsilon-near-zero structure could be used as a mirror inside a laser cavity enabling the development of lasers with tunable coherence properties. The metasurface used for generating partially coherent beams can replace bulky and expensive spatial light modulators in optical systems and provide improved resolution and efficiency. Plasmonic nanolasers can potentially be utilized in the future as on chip integrated light sources for optical telecommunications, and ultrasensitive biosensors.
What are the key research methods and materials used in your doctoral research?
The key methods included several nanofabrication processes, such as electron beam lithography, electron-beam evaporation, thermal evaporation, and reactive ion etching, as well as characterization tools such as ellipsometer, scanning-electron microscope and optical microscope. In addition, a wavelength tunable femtosecond laser was used in studying light-matter interactions.
The doctoral dissertation of Roman Calpe, MSc, entitled Engineering coherence of light with nanostructures: modulation and generation will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus. The opponent will be Associate Professor Nicklas Anttu, Åbo Akademi University, and the custos will be Assistant Professor Matias Koivurova, University of Eastern Finland. Language of the public defence is English.
