Terahertz pulse propagation in the near field and the far field

Andreas Gurtler, Carsten Winnewisser, Hanspeter Helm, Peter Uhd Jepsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We present a detailed investigation of the propagation properties of beams of ultrashort terahertz (THz) pulses emitted from large-aperture (LA) antennas. The large area of the emitter is demonstrated to have substantial influence on the temporal pulse profile in both the near field and the far field. We perform a numerical analysis based on scalar and vectorial broadband diffraction theory and are able to distinguish between near-field and far-field contributions to the total THz signal. We find that the THz beam from a LA antenna propagates like a Gaussian beam and that the temporal profile of the THz pulse, measured in the near field, contains information about the temporal and spatial field distribution on the emitter surface, which is intrinsically connected to the carrier dynamics of the antenna substrate. As a result of pulse reshaping, focusing of the THz beam leads to a reduced relative pulse momentum, with implications in THz field-ionization experiments. (C) 2000 Optical Society of America [S0740-3232(00)01001-2].
Original languageEnglish
JournalJournal of the Optical Society of America A
Volume17
Issue number1
Pages (from-to)74-83
Number of pages10
ISSN0740-3232
DOIs
Publication statusPublished - Jan 2000
Externally publishedYes

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