Conference Agenda

In recent years, optical nanofibres have become a promising platform for trapping, manipulating and controlling atomic systems. In this work, I will highlight our recent work on the demonstration of multiphoton processes using optical nanofibres embedded in a Rb MOT for the generation of entangled photons and the excitation of Rydberg atoms for all-fibred quantum networks.

We show that step-index multimode optical fibres retain memory of the radius at which they were illuminated, despite the output looking like a seemingly random speckle pattern. We characterize this radial memory effect, and discuss its application to spatial multiplexing for data transmission.

Optical nanofibers (ONFs) are highly suitable candidates for studying Brillouin scattering, thanks to their sub-optical and sub-acoustic wavelengths dimensions. The strong confinement of photons and acoustic phonons enhances the interaction and gives rise to several Brillouin backscattering spectra. In this work, we provide an experimental method based on pump/probe interaction in the radiofrequency domain to measure the Brillouin gain at different acoustic resonances.

We present measurements of the temperature of optical microfibers self-heated by a cw laser emitting at 1.48 µm. The experimental method we have implemented is simple and enables to perform for the first time to our knowledge spatially distributed measurements along the tapers and the microfiber part. Temperature rise of more than 20 °C is measured for moderate powers (200 mW) and relatively large radii (1.45 µm). The results are confronted to a numerical model we have developed and enable to determine range of values for the couple thermal transfer coefficient/surface absorption coefficient.

Optical fibers are of great technological importance due to their well-known unique features. Metasurfaces (MSs) are inhomegeneous 2D array of optical resonators, able to impress to the impinging beam an arbitrary modulation in amplitude, phase, polarization or frequency. Their integration on the tip of an optical fiber is able to enormously expand the fiber functionalities, by endowing a simple optical fiber with extraordinary capabilities of light manipulation. MSs are able to replace traditional bulky optical components, with the great advantage of reducing the size of the devices, thus representing a key element in a multitude of applications in modern optics, including fiber communications, analog computing, optical trapping, sensing, and imaging. In this work we exploit the paradigm of the metasurfaces based on partial-phase control in order to realize OFMT for two main applications: beam splitting and light focusing. In particular, we realized several OFMT featuring beam splitting at different angles and almost equal power on the two beams, and a focusing single-mode OFMT able to efficiently focus light at few microns from the fiber end facet, without the need of a beam expander. We show the design procedure, the fabrication process and the experimental characterization of the devices.