In her doctoral dissertation, Jiaqi Li investigates how light evolves inside multimode optical fibers and how nonlinear interactions can transform disordered, speckled outputs into highly structured beams. Her research shows that while linear propagation typically destroys spatial coherence, nonlinear effects – such as Kerr self-cleaning and Raman-driven mode competition – can spontaneously reorganize light into bright, stable spatial modes, including beams carrying orbital angular momentum. These findings deepen the understanding of multimode fiber physics and enable new opportunities for high-power fiber lasers, structured light sources, advanced imaging, and future photonic processing technologies.
The doctoral dissertation of MSc Jiaqi Li in the field of physics, titled Spatial Coherence, Multimode Dynamics, and Nonlinear Self-Organization in Multimode Optical Fibers, will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University on Friday 27 February 2026.
The Opponent will be Professor Massimo Giudici from Université Côte d’Azur, France. The Custos will be Professor Goëry Genty from the Faculty of Engineering and Natural Sciences, Tampere University.