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Tuesday, 27 May 2014

Malte: DM: Phase characterisation of plasmons

The field of plasmonics promises a brave new world of microprocessing, sensing and low-power nonlinear optics. Existing approaches to measuring plasmon fields using streaking are very involved, so an all-optical method to catch a glimpse of the surface dynamics is highly desirable. I carried out spectral interferometry on the reflected residual pump beam used to excite surface plasmon polaritons on a diffraction grating in order to characterise the phase of the propagating plasmon. I furthermore simulated the experimental situation using FDTD methods to connect the far-field results to the surface fields. Initial results show qualitative agreement between experiment and simulation, with the latter most likely critically limited by computational resources. As such, the progress so far demonstrates that the technique can indeed yield information about the plasmon dynamics in the far field with comparatively little experimental effort.

Tuesday, 20 May 2014

Will: JC: In situ measurement of nonlinear carrier-envelope phase changes in hollow fiber compression

We demonstrate a simple and robust single-shot interferometric technique that allows the in situ measurement of intensity-dependent phase changes experienced by ultrashort laser pulses upon nonlinear propagation. The technique is applied to the characterization of carrier-envelope phase noise in hollow fiber compressors both in the pressure gradient and in the static cell configuration. Measurements performed simultaneously with conventional f-to-2f interferometers before and after compression indicate that the noise emerging in the waveguide adds up arithmetically to the phase noise of the amplifier, thus being strongly correlated to the phase noise of the pulses coupled into the compressor.

Tuesday, 13 May 2014

Zsolt: JC: How to focus an attosecond pulse

Attosecond experiments involving focusing of attosecond light pulses can suffer from a spread of the attosecond radiation both in space and time due to optical aberrations. We present a detailed numerical study of the distortions induced in the most common focusing geometries that make use of parabolic, spherical, toroidal and ellipsoidal mirrors. We deduce the consequences on the pulse duration and possible issues that could arise in applications of attosecond pulses. This should serve as a guideline for setting up attosecond focusing optics.

Tuesday, 6 May 2014

Zolt: JC: Laser dressed absorption studies

Two papers will serve the bases:

Lucchini et al. Role of electron wavepacket interference in the optical response of helium atoms, NJP, 15, (2013)
Gallmann et al. Resolving intra-atomic electron dynamics with attosecond transient absorption spectroscopy, Molecular Physics, 111, (2013)