Effect of fibre endface angle on the measurement of the mode spot size from the far-field pattern

1984 ◽  
Vol 16 (5) ◽  
pp. 405-408
Author(s):  
G. Nicholson
Keyword(s):  
Spot Size ◽  
Field Pattern ◽  
Far Field ◽  
Far Field Pattern

Effect of transverse mode structure on the far field pattern of metal-metal terahertz quantum cascade lasers

2008 ◽  
Vol 104 (12) ◽  
pp. 124513 ◽  
Author(s):  
P. Gellie ◽  
W. Maineult ◽  
A. Andronico ◽  
G. Leo ◽  
C. Sirtori ◽  
...  
Keyword(s):  
Quantum Cascade Lasers ◽  
Transverse Mode ◽  
Field Pattern ◽  
Far Field ◽  
Mode Structure ◽  
Quantum Cascade ◽  
Metal Metal ◽  
Far Field Pattern ◽  
Cascade Lasers

Far-field patterns of line sources mounted between four-dielectric substrates

1992 ◽  
Vol 70 (2-3) ◽  
pp. 173-178 ◽  
Author(s):  
Ioanna Diamandi ◽  
Costas Mertzianidis ◽  
John N. Sahalos
Keyword(s):  
Remote Sensing ◽  
Line Source ◽  
Dielectric Substrate ◽  
Microstrip Antennas ◽  
Field Pattern ◽  
Substrate Thickness ◽  
Far Field ◽  
Dielectric Substrates ◽  
Field Patterns ◽  
Far Field Pattern

The far-field pattern characteristics of line sources lying between the slabs of a four-dielectric substrate configuration are presented. The patterns are calculated for several cases of the substrate thickness as well as for several line-source locations. The considerations that are made give useful applications in remote sensing and microstrip antennas.

scholarly journals Second harmonic generation from 3D nanoantennas: on the surface and bulk contributions by far-field pattern analysis

2011 ◽  
Vol 19 (27) ◽  
pp. 26752 ◽  
Author(s):  
Alessio Benedetti ◽  
Marco Centini ◽  
Mario Bertolotti ◽  
Concita Sibilia
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Pattern Analysis ◽  
Second Harmonic ◽  
Field Pattern ◽  
Far Field ◽  
Far Field Pattern

scholarly journals Scattering centers modeling of non-anechoic measurement environments

2012 ◽  
Vol 10 ◽  
pp. 69-73 ◽  
Author(s):  
K. A. Yinusa ◽  
C. H. Schmidt ◽  
T. F. Eibert
Keyword(s):  
Near Field ◽  
Field Measurements ◽  
Field Pattern ◽  
Far Field ◽  
Scattering Centers ◽  
Field Transformation ◽  
Field Radiation ◽  
Echo Suppression ◽  
Multipath Signals ◽  
Far Field Pattern

Abstract. Near-field measurements are established techniques to obtain the far-field radiation pattern of an Antenna Under Test via near-field measurements and subsequent near-field far-field transformation. For measurements acquired in echoic environments, additional post-processing is required to eliminate the effects of multipath signals in the resulting far-field pattern. One of such methods models the measurement environment as a multiple source scenario whereby the collected near-field data is attributed to the AUT and some scattering centers in the vicinity of the AUT. In this way, the contributions of the AUT at the probe can be separated from those of the disturbers during the near-field far-field transformation if the disturber locations are known. In this paper, we present ways of modeling the scattering centers on equivalent surfaces such that echo suppression is possible with only partial or no information about the geometry of the scatterers.

scholarly journals Progress towards the realization of an optical Far-Field Superlens

2021 ◽  
Author(s):  
◽  
Farzaneh Fadakar Masouleh
Keyword(s):  
Zinc Oxide ◽  
Near Field ◽  
Diffraction Gratings ◽  
Evanescent Waves ◽  
Field Pattern ◽  
Far Field ◽  
Potential Candidate ◽  
Plasmonic Material ◽  
Far Field Pattern ◽  
The Impact

<p>Conventional optics suffer from a fundamental resolution limit due to the nature of light. The near-field superlens concept was introduced two decades ago, and its theory for enabling high resolution imaging is well-established now. Initially, this superlens, which has a simple setup, became a hot topic given the proposition of overcoming the diffraction limit. It has been demonstrated that a near-field superlens can reconstruct images using evanescent waves emanating from small objects by means of resonant excitations on the surface of the superlens. A modified version of the superlens named the far-field superlens is theorized to be able to project the near-field subwavelength information to the far-field region. By design, the far-field superlens is a near-field superlens with nanostructures added on top of it. These nanostructures, referred to as diffraction gratings help couple object information available in the evanescent waves to the far-field. Work reported in this thesis is divided to two major sections. The first describes the modelling technique that investigates the performance of a far-field superlens. This section focuses on evaluating the impact of the diffraction gratings geometry and the object size on the far-field superlens performance as well as the resulting far-field pattern. It was shown that a far-field superlens with a nanograting having a duty cycle of 40% to 50% produces the maximum intensity and contrast in the far-field interactions. For periodic rectangular objects, an inverse-trapezoidal nanograting was shown to provide the best contrast and intensity for far-field interactions. The minimal simulation domain to model a symmetric far-field superlens design was determined both in 2D and 3D. This input reduced the required modelling time and resources. Finally, a 3D far-field superlens model was proposed, and the effect of light polarization on the far-field pattern was studied. The second section of this thesis contains the experimental study that explores a new material as a potential candidate for the construction of far-field superlens. The material conventionally used for superlens design is silver, as its plasmonic properties are well-established. However, scaling down silver features to the nanoscale introduces fundamental fabrication challenges. Furthermore, silver oxidizes due to its reactions with sulphur compounds at ambient conditions, which means that operating a silver far-field superlens is only possible in a well-controlled environment. This disagrees with our proposed concept of a low-cost and robust superlens imaging device. On the other hand, highly doped semiconductors are emerging candidates for plasmonic applications due to the possibility of tuning their optical and electrical properties during the fabrication process. While the working principle of a superlens is independent of the plasmonic material of choice, every plasmonic material has a particular range of operating wavelengths. The pros and cons of each plasmonic material are usually identified once used experimentally. In this work, aluminium-doped zinc oxide was the proposed material of choice for the far-field superlens design. The second part of this thesis details the characterization results of the optical, electrical and structural properties of this proposed alternative. Our aluminium-doped zinc oxide samples were highly transparent for large parts of the spectrum. Their carrier concentration was of the order of 10+20 cm-3, and a resistivity of about 10-3 Ω.cm was achieved. The modelled dielectric permittivity for the studied samples showed a cross-over frequency in the near-infrared region, with the highest plasma frequency achieved in this study being 4710 cm-1.</p>

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