The doctoral dissertation in the field of Photonics will be examined at the Faculty of Science and Forestry on the Joensuu Campus.
What is the topic of your doctoral research, Henri Pesonen?
In the thesis I investigate the modulation of partially coherent pulse trains with widely used linear and nonlinear optical elements, such as interferometers, gratings, and nonlinear crystals.
Partially coherent pulsed light fields are frequently employed in modern photonics. Examples cover correlation imaging, inertial confinement fusion, telecommunication, micro-machining, etc. However, at present, there is a severe lack of flexible and reliable methods to produce pulse trains of controlled coherence properties.
What are the key findings or observations of your doctoral research?
Key findings are:
1. A Fabry-Perot interferometer can be used to increase the degree of temporal coherence of pulse trains or induce a periodic coherence modulation.
2. The intensity, polarization, and temporal coherence of pulse trains can be controlled by a resonance grating. In particular, a fully polarized pulse train can become partially polarized in grating reflection.
3. A nonlinear crystal exhibiting second-harmonic generation can be used to control and modulate the spatial coherence properties of stationary light beams as well as the temporal and spectral coherence of pulse trains.
How can the results of your doctoral research be utilized in practice?
The findings of the thesis provide novel methods for tailoring the coherence characteristics of continuous wave and pulsed optical fields.
What are the key research methods and materials used in your doctoral research?
The work encompasses theoretical research with analytical and computational parts. The numerical methods were developed for the present context and implemented by me.
The doctoral dissertation of Henri Pesonen, MSc, entitled Modulation of partially coherent light beams by linear and nonlinear elements will be examined at the Faculty of Science and Forestry on 10th December 2021 at noon in Joensuu Campus, Metria building, Auditorium 101. The opponent in the public examination will be Professor Sergei Popov of Royal Institute of Technology (KTH) and the custos will be Professor Tero Setälä of University of Eastern Finland. Language of the public defence is English.
