Master Thesis Defense by Bjarke Takashi Røjle Christensen – Niels Bohr Institute - University of Copenhagen

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Master Thesis Defense by Bjarke Takashi Røjle Christensen

"A laser system in the deep ultra violet is developed for application in an optical
lattice clock based on neutral mercury atoms. The ultraviolet light is achieved
by a two step frequency doubling of a distributed Bragg reflector fiber laser lasing
at 1062.6 nm. The fiber laser is constructed from a highly Ytterbium-doped fiber
spliced directly inbetween two fiber Bragg gratings with parameters suitable for
operation at 1062.6 nm. Single frequency operation is obtained. The required wavelength
265.6nm is obtained within the tuning range of the clock laser system. The
output power of the fiber laser is amplified by an Ytterbium doped fiber amplifier to
meet the power requirement for the clock laser. Frequency doubling is performed by
usage of a waveguide module setup and a cavity enhanced second harmonic generation
setup. An output power of 3mW is obtained at 265.6 nm. The frequency of the
laser is stabilized to a high finesse cavity with spacers made of ultra low expansion
glass as a frequency reference. The linewidth of the stabilized fiber laser is evaluated
to be limited by the linewidth of the high finesse cavity."