Complex Source Pulsed Beams: Propagation, Scattering and Applications
The excitation, propagation and diffraction of short pulse signals is receiving increased attention in a variety of fields. Due to the broad frequency spectra of such signals, the conventional route of inversion from the frequency domain is often less convenient, and physically less transparent, than direct treatment of time domain events. Analysis and synthesis of such wave solutions require use of source functions (e.g., time-dependent Green’s functions or plane waves). Important among source functions, for a variety of applications (some examples will be given below), are those which establish well focused fields. In the frequency domain, such fields take the form of transversely confined beams, the most favored among which have Gaussian-like profiles. In the time domain, such fields take the form of pulsed teams (PB), i.e. highly directed space-time wave packets. Several types of PB solutions of the wave equation have recently been introduced,1“3 in particular in connection with long range focused energy transfer. Particular interest has been given to the focus wave modes (FWM)1 and the related wave functions,2 which are non diffracting or slowly diffracting free space wave packets. However, since these exact solutions comprise backward propagating spectral components, their role in modeling physical radiation is yet to be clarified.4“6 Efforts have been made to minimize the backward propagating part in these exact solutions,7 but the effect of eliminating them completely has not yet been fully established.
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