Complex structured light and its interaction with matter

Shaping light fields in time, space, and polarization has become a versatile tool to explore fundamental optics effects and explore fruitful applications in various fields of photonics. In this talk, I will present two of our recent studies in this thriving branch of optics
At first, I will describe our recent results in structuring light in polarization, space, and wavelength. Through a combination of a polarization-dependent modulation in time and in orbital angular momentum, we are able to realize pulses of light, that are fully correlated in all three degrees of freedom, which we term spatio-spectral vector beams. We show that such beams have a complex polarization pattern over the wavelength spectrum as well as transverse angle. We further explore an interesting feature, namely that the degree of polarization of the field is only unveiled when the field is narrowly defined in space and wavelength, which is analog to non-separable quantum systems.
In the second part of the talk, I will discuss higher-order aberration effects that are natural to reflections of light with spatial structures such as phase vortices. In such scenarios, it was predicted that higher-order vortices split into a constellation of unit-charged vortices, a phenomenon termed as topological aberration. We were able to observe this phenomenon for the first time experimentally through the transformation of a vortex constellation upon reflection. We developed a general theoretical framework to study topological aberrations in terms of elementary symmetric polynomials of the coordinates of a vortex constellation. This mathematical abstraction, which we prove to be the physical quantity of interest, not only allowed us to verify the effect experimentally, but might also be applicable to vortex constellations of more complex structured light fields as well as other physical systems e.g. superfluids and Bose-Einstein condensates.