Promotionsvortrag Physik:"Helical Bloch Modes in Twisted Photonic Crystal Fibers"

Feb 24
24. February 2021 14:00 - 15:00
Bibliothek A. 2.500, MPL, Staudtstr. 2, Erlangen

Ankündigung des Promotionsvortrags von: Herrn Paul Roth

Helically twisted photonic crystal fibers (PCFs), formed either by spinning the preform during fiber drawing or by thermal post-processing, exhibit many interesting optical effects.
This is because the transverse microstructure of PCF imposes non-circularity on the guided modes, forcing the guided helical Bloch mode patterns to rotate as they propagate in twisted PCF.

In this work a phase shifting interferometric technique was introduced, which enables the measurement of the spatial phase and intensity distributions of helical Bloch modes.
Using this technique the spectra of azimuthal Bloch harmonics carried by helical Bloch modes in twisted coreless PCFs were retrieved.
Strong circular dichroism was studied in twisted single-ring PCF. The chiral structure allowed a single circularly polarized core mode to couple to a high loss cladding mode, while the core mode of the opposite circular polarization is transmitted with low loss. The generation of circularly polarized supercontinuum light carrying optical vortices was demonstrated using a twisted PCF with a threefold symmetric core.

Finally, cross-phase modulational instability in twisted three-core PCF was demonstrated for the first time. Measurements showed that the sidebands were orthogonally polarized and carry orbital angular momentum of opposite chirality. These results may find applications in parametric amplification and generation of vortex modes.

(Vortrag auf Englisch)

Dem Vortrag schließt sich eine Diskussion von 15 Minuten an. Vortrag und Diskussion sind aufgrund der momentanen Situation nicht öffentlich. Diesen Verfahrensteilen folgt ein ebenfalls nicht öffentliches Rigorosum von 45 Minuten.