Public defence in Engineering Physics, M.Sc. (Tech) Panu Hildén

Title of the thesis: Non-diffractive structured light fields: Generation, properties, and applications

Doctoral Student: Panu Hildén
Opponent: Professor Miguel Alonso, Centrale Méditerranée, France & The Institute of Optics, University of Rochester, USA
Custos: Professor Emeritus Matti Kaivola, Aalto University School of Science, Department of Applied Physics

Propagation of light, and its control, are subject to intense research within the field of optics and photonics. This control enables improvements in numerous light-based technologies. The propagation of light can be controlled either by engineering the structure of the propagation medium, or the light itself. The goal of this thesis is to advance the generation of propagation-invariant light fields, and their application in laser beam engineering, optical imaging, and photonic integrated circuits.

In this work, we report a method for forming diffraction-free laser beams with intensity peaks that propagate at an arbitrarily chosen velocity. The intensity peaks could be used to trap small particles, like in optical tweezers, and therefore control their movement. Another novel optical beam, namely a two-dimensional non-diverging light sheet, is also presented. These light sheets, which can be generated using custom design compound prism, are extremely narrow and long, which is desirable for many of their applications. Additionally, an imaging system with an extraordinarily long depth of field is demonstrated. This means that the system can form sharp images of objects displaced far from the focus. Finally, crosstalk between waveguides carrying optical signals is investigated. It is shown analytically how the crosstalk in waveguide arrays can be reduced by deliberately bending the waveguides. The reduction in crosstalk enables denser packaging of optical components on photonic integrated circuits without hindering their performance, thus helping to reduce the footprint of the chip.

Overall, the results presented in this work can help to advance the development of wide variety of optic and photonic devices.

Key words: structured light, diffraction cancelation, extended depth of field, waveguide crosstalk 

Thesis available for public display 10 days prior to the defence at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/

Contact information:

Doctoral theses at the School of Science: https://aaltodoc.aalto.fi/handle/123456789/52