Public defence in Engineering Physics, M.Sc. Somendu Maurya
Title of the doctoral thesis: Control of light coherence, polarization, and propagation using nanostructures
Opponent: Professor Taco Dirk Visser, University of Rochester, USA
Custos: Professor (emer.) Matti Kaivola, Aalto University School of Science, Department of Applied Physics
The doctoral thesis is publicly displayed 10 days before the defence in the publication archive Aaltodoc of Aalto University
The emerging field of nanophotonics has pioneered the modern-day scientific quest for nanostructured optical components with new capabilities to control the properties of light. These capabilities are a result of unique light-matter interactions that take place when the building blocks of the device are comparable to or smaller than the wavelength of light. This thesis builds up on these advancements and proposes new nanostructured materials and devices based on them. The thesis also introduces new calculation methods for the design of such optical systems and for analysis of their performance.
The thesis describes novel metal-dielectric nanostructures designed to control the polarization properties of light. A nanofabricated waveplate with a thickness smaller than the wavelength is an example of such structures. Waveplates of this type can operate in a large wavelength range with low losses in the transmission mode. Another similar nanostructure has been demonstrated to act as a tunable partial polarizer. It selectively reduces the intensity of one polarization component of light such that the degree of polarization of the transmitted field depends on the angle of incidence. The thesis also introduces new semi-analytical methods to calculate the spatial coherence properties of optical near- and far-fields produced by nanostructured sources.
The thesis also investigates the propagation of light in nano- and micro-waveguides on a photonic chip. The crosstalk between such waveguides prevents their dense integration. The thesis presents a solution to this problem by replacing the fundamental modes of the waveguides with either radially or azimuthally polarized higher-order modes. The results presented in this thesis enable the development of advanced optical devices for light generation and detection, as well as for optical information processing and communication.
Contact details of the doctoral student: [email protected]