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DY: Fachverband Dynamik und Statistische Physik

DY 27: Nonlinear Dynamics, Synchronization and Chaos - Part II

DY 27.3: Vortrag

Donnerstag, 3. April 2014, 10:00–10:15, ZEU 160

“Beating” beats “Mixing” in Heterodyne Detection Schemes — •Gerard J. Verbiest¹ and Marcel J. Rost² — ¹JARA-FIT and II. Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany — ²Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands

Heterodyne detection schemes are widely used, as one can measure extremely high-frequencies signals that are otherwise difficult, or even impossible, to measure experimentally. A heterodyne detection scheme can down-convert a high-frequency signal to a lower, easily measurable frequency by mixing it with a reference signal. In general, beating and mixing are contrary effects: beating occurs with a linear interaction, whereas heterodyne mixing occurs, if the interaction is nonlinear. Therefore, beating is ought to be unimportant in heterodyne schemes, as it does not generate a mixing signal. In contrast to this, we show via a derivation of a general analytical model [1] that both beating and mixing are necessary to explain the generation of the heterodyne signal. Beating even dominates the heterodyne signal generated by mixing, if the nonlinearity of the system is of higher order than quadratic. Standard textbook equations fail in this case, as they are usually based on second order approximations. We confirm our results with both an experiment [2] and a full numerical calculation [3] on the example of Heterodyne Force Microscopy.

[1] G.J. Verbiest, and M.J. Rost, Nature Physics submitted

[2] G.J. Verbiest et al., Nanotechnology 24, 365701 (2013)

[3] G.J. Verbiest et al., Ultramicroscopy 135, 113 (2013)