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Tuesday, 30 July 2013

Felicity: Extending HHG Spectroscopy to New Molecular Species

18 month transfer presentation. This presentation details the objectives of this PhD project and the current status of experiments. A review of the first apparatus which did yield Benzene HHG at 1500nm, albeit with limited success is presented along with the developments taken to construct the current apparatus. The acquisition of HHG spectra in a variety of molecules and ellipticity scans are presented along with impulsive alignment of the benzene molecule. The intended experiments which include the Jahn Teller Effect and PACER will be presnted and the possibility of working with other targets and spectroscopic methods will also be discussed.

Tuesday, 23 July 2013

William: DM: CEP stability of hollow-fibers used for high-energy, few-cycle pulse generation

We investigated the carrier-envelope phase (CEP) stability of a hollow-fiber setup used for high-energy, fewcycle pulse generation. Saturation of the output pulse energy is observed at 0:6 mJ for a 260µm inner-diameter,
1 m long fiber, statically filled with neon, with the pressure adjusted to achieve an output spectrum capable
of supporting sub-4 fs pulses. The maximum output pulse energy can be increased to 0:8 mJ by using either
differential pumping, or circularly polarized input pulses. We observe the onset of an ionization-induced CEP
instability, which does not increase beyond an input pulse energy of 1:25 mJ due to losses in the fiber caused
by ionization. There is no significant difference in the CEP stability with differential pumping compared to
static-fill, demonstrating that gas flow in differentially pumped fibers does not degrade the CEP stabilization