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Near and far field

About: Near and far field is a research topic. Over the lifetime, 15922 publications have been published within this topic receiving 220571 citations.


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TL;DR: This work directly maps the intensity of the electric field close to plasmonic nanoantennas using diffraction-unlimited far-field spectroscopy in the infrared, and measures for the first time the near-field intensity of a three-dimensional plAsmonic electromagnetically induced transparency structure.
Abstract: Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light-matter coupling and is of special interest for applications such as radiation engineering, attomolar sensing and nonlinear optics. Most experimental approaches to measure near-fields employ either diffraction-limited far-field methods or intricate near-field scanning techniques. Here, using diffraction-unlimited far-field spectroscopy in the infrared, we directly map the intensity of the electric field close to plasmonic nanoantennas. We place a patch of probe molecules with 10 nm accuracy at different locations in the near-field of a resonant antenna and extract the molecular vibrational excitation. We map the field intensity along a dipole antenna and gap-type antennas. Moreover, this method is able to assess the near-field intensity of complex buried plasmonic structures. We demonstrate this by measuring for the first time the near-field intensity of a three-dimensional plasmonic electromagnetically induced transparency structure.

104 citations

Journal ArticleDOI
TL;DR: In this paper, the generalized reflection and transmission coefficients of vector wave fields containing evanescent components were derived by using Lorentz's reciprocity theorem with sources at finite distance from the scatterer.
Abstract: We derive reciprocity relations for the generalized reflection and transmission coefficients of vector wave fields containing evanescent components. This is done by using Lorentz’s reciprocity theorem with sources at finite distance from the scatterer.

104 citations

Journal ArticleDOI
TL;DR: It is observed, that holes can act as differential operators whose near-field output is the time-derivative of the incident electric field.
Abstract: Using terahertz-light excitation, we have measured with sub-wavelength spatial, and sub-cycle temporal resolution the time- and frequency-dependent electric-field and surface-charge density in the vicinity of small metallic holes. In addition to a singularity like concentration of the electric field near the hole edges, we observe, that holes can act as differential operators whose near-field output is the time-derivative of the incident electric field. Our results confirm the well-known predictions made by Bouwkamp, Philips Res. Rep. 5, 321-332 (1950), and reveal, with unprecedented detail, what physically happens when light passes through a small hole.

103 citations

Journal ArticleDOI
TL;DR: In this paper, a procedure is developed to predict electromagnetic interference from electronic products using near-field scan data, which is used to define equivalent electric and magnetic current sources characterizing the electromagnetic emissions from an electronic circuit.
Abstract: A procedure is developed to predict electromagnetic interference from electronic products using near-field scan data. Measured near-field data are used to define equivalent electric and magnetic current sources characterizing the electromagnetic emissions from an electronic circuit. Reconciliation of the equivalent sources is performed to allow the sources to be accurately applied within full-wave numerical modeling tools like finite-difference time domain (FDTD). Results show that the radiated fields must typically be represented by both electric and magnetic current sources if scattering and multiple-reflections from nearby objects are to be taken into account. The accuracy of the approach is demonstrated by predicting the fields generated by a microstrip trace within and outside of a slotted enclosure, and by predicting the fields generated by the microstrip trace close to a long wire. Values predicted from near-field scan data match those from full-wave simulations or measurements within 6 dB.

103 citations

Journal ArticleDOI
TL;DR: In this paper, the authors considered the scattering of time harmonic electromagnetic plane waves by a bounded inhomogeneous medium and showed that under certain assumptions a lower bound on the index of refraction can be obtained from a knowledge of the smallest transmission eigenvalue corresponding to the medium.
Abstract: We consider the scattering of time harmonic electromagnetic plane waves by a bounded inhomogeneous medium and show that under certain assumptions a lower bound on the index of refraction can be obtained from a knowledge of the smallest transmission eigenvalue corresponding to the medium. It is then shown by numerical examples that this eigenvalue can be determined from a knowledge of the far field pattern of the scattered wave, thus providing a practical method for estimating the index of refraction from far field data.

103 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023132
2022281
2021376
2020460
2019640
2018604