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