Master Thesis Defense by Christine Pepke Pedersen – University of Copenhagen

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Master Thesis Defense by Christine Pepke Pedersen

Characterizing thermal properties of tapered nanofibers 

Optical fibers reshaped to subwavelength diameters have emerged as an intersting platform for atomic physics and quantum optics experiments in recent years. A substantial
fraction of light guided by nanofibers with typical diameters of 500nm travels close to the
surface outside the fiber  and can interact there efficiently with atoms held in proximity to the surface. One major technical  challenge for experiments arises from the high light intensity needed to trap atoms near the fiber surface. Even a minute concentration of absorbers on the surface can provide a highly concentrated heat load and ultimately lead to local melting and destruction of the fiber. During the project an interferometer setup to measure the heat induced expansion of nanofibers has been built. I present measurements on the transient heating and cooling behaviour of carefully pulled nanofibers in vacuum, compare with existing data and models from the literature, and give an answer to the question whether there is a tell-tale signal of a fiber starting to melt.