Waitz, Reimar

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Quantitative signal extraction in the dynamic range of nanomechanical systems by free and constrained fitting

2023, Yang, Fan, Waitz, Reimar, Fu, Mengqi, Scheer, Elke

We present a free and a constrained fitting procedure for determining the intrinsic response of a nanomechanical systems subject to noise and other environmental influences. We demonstrate that applying the free fitting procedure to the measured frequency response of amorphous silicon nitride (SiN) nanomembranes at varying pressure enables us to disentangle the intrinsic membrane vibration properties from the system response. This approach gives quantitative access to the eigenfrequency, quality factor, coupling strength to the excitation system as well as to system noise. The validity of physical models for quantities such as excitation, fluctuations, and damping can be verified with the help of the constrained fitting procedure that implies additional mathematical relationships between the fit parameters. We verify the performance of the constrained fitting procedure for amorphous SiN membrane resonators tested in various experimental setups.

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Lateral and Temporal Dependence of the Transport through an Atomic Gold Contact under Light Irradiation : Signature of Propagating Surface Plasmon Polaritons

2014, Benner, Daniel, Boneberg, Johannes, Nürnberger, Philipp, Waitz, Reimar, Leiderer, Paul, Scheer, Elke

Metallic point contacts (MPCs) with dimensions comparable to the Fermi wavelength of conduction electrons act as electronic waveguides and might operate as plasmon transmitters. Here we present a correlated study of optical and conductance response of MPCs under irradiation with laser light. For elucidating the role of surface plasmon polaritons (SPPs), we integrate line gratings into the leads that increase the SPP excitation efficiency. By analyzing spatial, polarization, and time dependence, we identify two SPP contributions that we attribute to transmitted and decaying SPPs, respectively. The results demonstrate the role of SPPs for optically controlling the transport in metallic nanostructures and are important for designing opto-nanoelectronic devices.

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Characterization and applications of plasmon fields in metal nanostructures

2011-12-23, Kolloch, Andreas, Benner, Daniel, Bädicker, Matthias, Waitz, Reimar, Geldhauser, Tobias, Boneberg, Johannes, Leiderer, Paul, Scheer, Elke

The excitation of plasmons in metallic nanostructures by light can give rise to pronounced local optical field enhancement with respect to the incident electromagnetic field. The details of these optical near fields depend sensitively on the properties of the nanostructures (material, size and shape), on the light wavelength and polarization, and also on the substrate. In this article we discuss several of these aspects influencing the near-field distribution for a given object and the resulting surface ablation by optical near fields. To this end we use both experimental and simulation techniques. Additionally we will present first results of experiments investigating the light emitted during nanoscale ablation. Finally, we will present an example how plasmon-mediated near-field effects act on the conductance of atomic-size contacts.