Developments in Femtosecond Nanoelectronics

Herink, Georg

Ultrafast Emission and Control of Electrons in Optical Near-Fields

dc.contributor.advisor	Ropers, Claus Prof. Dr.
dc.contributor.author	Herink, Georg
dc.date.accessioned	2015-01-21T10:34:03Z
dc.date.available	2015-01-21T10:34:03Z
dc.date.issued	2015-01-21
dc.identifier.uri	http://hdl.handle.net/11858/00-1735-0000-0022-5D8B-1
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-4874
dc.language.iso	eng	de
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/3.0/
dc.subject.ddc	530	de
dc.title	Developments in Femtosecond Nanoelectronics	de
dc.title.alternative	Ultrafast Emission and Control of Electrons in Optical Near-Fields	de
dc.type	doctoralThesis	de
dc.contributor.referee	Ropers, Claus Prof. Dr.
dc.date.examination	2014-12-16
dc.subject.gok	Physik (PPN621336750)	de
dc.description.abstracteng	Coupling light to metal surfaces can break the diffraction limit and concentrate optical fields at the nanoscale. The studies presented in this cumulative thesis investigate the influence of optical field localization onto strong-field photoemission from metallic nanotips in a spectral range from near- to far-infrared frequencies (1 - 400 Terahertz). Intense infrared excitation is demonstrated to provide access to the strong-field photoemission regime and to the ponderomotive scaling of the electron kinetic energy. Specifically, at long wavelengths, conditions are reached, in which the quiver amplitude of the photoelectrons can exceed the dimension of the localized driving field. As a result, the light-electron interaction is confined to a fraction of the optical half-cycle, enabling quasi-instantaneous field-driven electron acceleration. A spatial adiabaticity parameter is introduced to classify the experimentally observed transition in the electron energy scaling and to distinguish the oscillatory and the sub-cycle acceleration regimes. The adaptation of a two-step model of strong-field photoemission for near-fields allows for the quantitative numerical analysis of the spatio-temporal dynamics and the reproduction of the experimental findings. In another set of experiments, employing a two-color streaking scheme with near-infrared and Terahertz (THz) pulses, the local THz-waveform at the emission site is temporally mapped and the sub-cycle acceleration dynamics are resolved in-phase. Moreover, electron dynamics at the transition from oscillatory to sub-cycle acceleration are studied via streaking experiments and numerical simulations. The findings demonstrate new schemes for the ultrafast manipulation of electron trajectories during their transit in time-varying near-fields. Direct applications arise, e.g., in the compression of electron pulses, and are sketched at the end of this work. Finally, the high field enhancement at long wavelengths is demonstrated to enable ultrafast cold field emission with THz-radiation. Peaked at high energies, the observed energy spectra reveal the characteristic signatures of emission and acceleration in the sub-cycle regime. Moreover, the nonlinearity of the field emission process is employed to temporally track the picosecond carrier cooling at the nanotip apex after intense near-infrared excitation. The findings indicate reduced cooling-rates due to the nanoscopic heat confinement and establish an optical-pump / field-emission-probe scheme for the local access to carrier-dynamics in nanostructures.	de
dc.contributor.coReferee	Salditt, Tim Prof. Dr.
dc.contributor.thirdReferee	Hecht, Bert Prof. Dr.
dc.subject.eng	Nonlinear Photoemission	de
dc.subject.eng	Strong-field Physics	de
dc.subject.eng	Mid-Infrared spectroscopy	de
dc.subject.eng	Photoemission	de
dc.subject.eng	Field emission	de
dc.subject.eng	Terahertz spectroscopy	de
dc.subject.eng	Nanostructures	de
dc.subject.eng	Nano-optics	de
dc.subject.eng	Streaking spectroscopy	de
dc.subject.eng	Nanoelectronics	de
dc.subject.eng	Laser	de
dc.subject.eng	Near-fields optics	de
dc.subject.eng	Nanotip	de
dc.subject.eng	Ultrafast spectroscopy	de
dc.subject.eng	AC-tunneling	de
dc.identifier.urn	urn:nbn:de:gbv:7-11858/00-1735-0000-0022-5D8B-1-1
dc.affiliation.institute	Fakultät für Physik	de
dc.identifier.ppn	815977344

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