This presentation offers a comprehensive journey through the physics of multimode optical fibers, exploring their nonlinear dynamics and advanced characterization techniques. We trace how intense femtosecond pulses in graded- and step-index fibers give rise to extreme nonlinear phenomena such as multiphoton absorption, up-conversion luminescence, beam self-cleaning, and the formation of helical plasma filaments. These effects are interpreted within the emerging thermodynamic framework of multimode “photon gases,” highlighting concepts such as thermalization, entropy growth, and beam-quality evolution. Complementing the optical studies, the talk presents state-of-the-art X-ray microtomography and small-angle X-ray scattering as powerful tools to reconstruct refractive-index profiles, assess material composition, and probe nanoscale structural changes in both silica and polymer fibers. Together, these results advance our understanding of nonlinear light–matter interactions in complex waveguides and support the development of next-generation high-power fiber systems and specialty fiber technologies.

Online: https://uw-edu-pl.zoom.us/j/92289876379?pwd=QnuKSbB05kBsENtaWACbiGLULYr8q0.1

Identyfikator spotkania: 922 8987 6379

Kod dostępu: 951801