scholarly journals Deep Subwavelength Power Concentration-Based Hyperbolic Metamaterials

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Amanpreet Kaur ◽  
Saptarshi Banerjee ◽  
Wangshi Zhao ◽  
Jayanti Venkataraman ◽  
Zhaolin Lu
Keyword(s):  
Electromagnetic Waves ◽  
Light Propagation ◽  
Spot Size ◽  
Diffraction Limit ◽  
Evanescent Waves ◽  
Hyperbolic Metamaterials ◽  
Preferred Direction ◽  
Propagating Waves ◽  
Medium Design ◽  
Collimated Beam

Hyperbolic metamaterials can manipulate electromagnetic waves by converting evanescent waves into propagating waves and thus support light propagation without diffraction limit. In this paper, deep subwavelength focusing (or power concentration) is demonstrated both numerically and experimentally using hyperbolic metamaterials. The results verify that hyperbolic metamaterials can focus a broad collimated beam to spot size of ~λ0/6 using wired medium design for both normal and oblique incidence. The nonmagnetic design, no-cut-off operation, and preferred direction of propagation in these materials significantly reduce the attenuation in electromagnetic waves.

scholarly journals A Method for Fabricating Arrays of Nanopatterns with the Feature Size beyond Diffraction Limit

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Shuhong Li ◽  
Lifang Shi ◽  
Xiaochun Dong ◽  
Chunlei Du ◽  
Yudong Zhang
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Diffraction Limit ◽  
Evanescent Waves ◽  
The Other ◽  
Optical Intensity ◽  
Polystyrene Spheres ◽  
Feature Size ◽  
Contact Points ◽  
Difference Time

A convenient lithographic technique is proposed in this paper, which can be used to produce subdiffraction-limit arrays of nanopatterns over large areas (about several square centimeters). An array of polystyrene spheres (PS) is arranged on the surface of a layer of silver which has a thickness of about tens of nanometers. With the normal illumination light of wavelength 365 nm perpendicular to the substrate, PS can generate an array of optical patterns with high intensity at their contact points with silver. By designing the silver slab, the evanescent waves that carry subwavelength information about the optical patterns are substantially enhanced, while propagating components are restrained. In the photoresist which is on the other side of silver, the optical intensity is redistributed and subdiffraction-limit patterns are obtained after exposure and development. Simulation by finite-difference time-domain (FDTD) and experiments were carried out to verify the technique. The results show that by using PS with diameter of 600 nm, nanopatterns with dimension of less than 80 nm can be obtained.

FDTD Simulation of Light Propagation Inside a-Si:H Structures

2010 ◽  
Vol 1245 ◽  
Author(s):  
Alessandro Fantoni ◽  
Pedro Pinho
Keyword(s):  
Light Absorption ◽  
Electromagnetic Waves ◽  
Light Propagation ◽  
Light Transmission ◽  
Visible Spectrum ◽  
Propagation Model ◽  
Interface Roughness ◽  
Fdtd Simulation ◽  
Doping Density ◽  
Surface And Interface

AbstractWe have developed a computer program based on the Finite Difference Time Domain (FDTD) algorithm able to simulate the propagation of electromagnetic waves with wavelengths in the range of the visible spectrum within a-Si:H p-i-n structures. Understanding of light transmission, reflection and propagation inside semiconductor structures is crucial for development of photovoltaic devices. Permitting 1D analysis of light propagation over time evolution, our software produces results in well agreement with experimental values of the absorption coefficient. It shows the light absorption process together with light reflection effects at the incident surface as well as at the semiconductor interfaces. While the effects of surface reflections are easily taken into account by the algorithm, light absorption represents a more critical point, because of its non-linear dependence from conductivity. Doping density, density of states and photoconductivity calculation are therefore crucial parameters for a correct description of the light absorption-transmission phenomena through a light propagation model.The results presented in this paper demonstrate that is possible to describe the effect of the light-semiconductor interaction through the application of the FDTD model to a a-Si:H solar cell. A more general application of the model to 2D geometries will permit the analysis of the influence of surface and interface roughness on the device photovoltaic efficiency.

scholarly journals COSMOLOGICAL CONSTANT AND THE SPEED OF LIGHT

2001 ◽  
Vol 10 (01) ◽  
pp. 41-48 ◽  
Author(s):  
W. R. ESPÓSITO MIGUEL ◽  
J. G. PEREIRA
Keyword(s):  
Gravitational Field ◽  
Cosmological Constant ◽  
Electromagnetic Waves ◽  
Light Propagation ◽  
Wave Optics ◽  
Speed Of Light ◽  
Positive Cosmological Constant ◽  
Velocity Of Light ◽  
Refractive Medium ◽  
The Relationship

By exploring the relationship between the propagation of electromagnetic waves in a gravitational field and the light propagation in a refractive medium, it is shown that, in the presence of a positive cosmological constant, the velocity of light will be smaller than its special relativity value. Then, restricting again to the domain of validity of geometrical optics, the same result is obtained in the context of wave optics. It is argued that this phenomenon and the anisotropy in the velocity of light in a gravitational field are produced by the same mechanism.

Observation of Scattered Evanescent Waves

2005 ◽  
Vol 295-296 ◽  
pp. 649-654
Author(s):  
M. Ozaki ◽  
Ryoshu Furutani
Keyword(s):  
Spatial Resolution ◽  
Evanescent Wave ◽  
Diffraction Limit ◽  
Evanescent Waves ◽  
Scanning Tunneling ◽  
Object Surface ◽  
Tunneling Microscopy ◽  
Fiber Probe ◽  
Distance Constant ◽  
Sample Distance

Spatial resolution in the conventional optical microscopy depends on diffraction limit. Photon scanning tunneling microscopy is one of the microscopic methods that surpass the diffraction limit. It scans an object with detecting evanescent wave on object surface. Evanescent wave is scattered by the tip of a fiber probe and guided to a detector by the fiber probe. Not all of the scattered ray can be detected. Only the scattered ray from the aperture of a fiber probe can be detected. We propose to improve an image by detecting the state of scattered ray and a new method to maintain the probe sample distance constant by keeping the quantity of scattered ray constant.

DIFFRACTION OF 3.2 CM. ELECTROMAGNETIC WAVES BY DIELECTRIC RODS: III. LUCITE IN. DIAMETER SEMICYLINDER, FIELDS VERY CLOSE TO SURFACE

1957 ◽  
Vol 35 (11) ◽  
pp. 1253-1264 ◽  
Author(s):  
A. B. McLay ◽  
C. E. Jordan
Keyword(s):  
Electromagnetic Waves ◽  
Plane Surface ◽  
Near Field ◽  
Aluminum Foil ◽  
Evanescent Waves ◽  
Incident Field ◽  
Thin Aluminum ◽  
Diffraction Patterns ◽  
Thin Aluminum Foil

The diffraction fields near a long, semicylindrical, [Formula: see text] in. diameter rod of lucite, oriented in a nearly plane incident field of 3.2 cm. waves with plane surface towards or away from the source, have been reinvestigated in the region very close to the rod more thoroughly than previously (McLay and Subbarao 1956). The incident field was polarized parallel to the long axis of the semicylinder. In addition, the field near the rod when it was oriented with plane surface aligned with the axis of propagation and the field when the same rod was coated with thin aluminum foil and placed in turn in each of the three above-mentioned orientations have now been observed.A number of features in the diffraction patterns of the uncoated lucite rod have been qualitatively accounted for as resulting from effects of weak radiation after one or more internal reflections, or from evanescent waves close to a part of the surface where internal incidence is at angles greater than critical, superposed on one or more of the incident, directly transmitted and externally reflected radiations. The patterns a little away from the surface of the uncoated rod and the whole patterns of the aluminum-coated one are quite simple relatively and provide evidence of marked near-field diffraction.

Dispersion relations and wave propagation in photonic hypercrystals

2018 ◽  
Vol 32 (02) ◽  
pp. 1750320 ◽  
Author(s):  
Munazza Zulfiqar Ali
Keyword(s):  
Wave Vector ◽  
Dielectric Material ◽  
Effective Medium ◽  
Evanescent Waves ◽  
Dispersion Relations ◽  
Matrix Approach ◽  
Periodic Medium ◽  
Hyperbolic Metamaterial ◽  
Propagating Waves ◽  
Transfer Matrix Approach

A photonic hypercrystal is a subwavelength periodic structure consisting of alternate layers of hyperbolic metamaterial and dielectric material. The structure can be treated as an effective medium as well as a periodic medium. Since two length scales are involved, the better treatment is to treat the hyperbolic metamaterial as an effective medium and the overall structure as a periodic medium. The dispersion relations are derived and plotted to show the appearance of propagating bands and gaps in the frequency and wave vector domains. Then using the transfer matrix approach, the transmissivity versus the frequency plot for propagating waves and grayscale plot of the transmission coefficient in the frequency versus wave vector plane for the evanescent waves are plotted and analyzed.

On Mechanics of Light Propagation in Free Space with Final Temperature

2007 ◽  
Vol 3 (2) ◽  
pp. 220-231
Author(s):  
M. Ja. Ivanov ◽  
V.K. Mamaev
Keyword(s):  
Exact Solutions ◽  
Free Space ◽  
Electromagnetic Waves ◽  
Light Propagation ◽  
Longitudinal Component ◽  
Final Temperature ◽  
Final Density ◽  
Propagation Of Light ◽  
Waves Propagation ◽  
Modified Theory

Features of electromagnetic waves propagation of light range are considered in free space with final temperature 2.725K. The presence in space of temperature (and final density) allows justification to introduce the longitudinal component of electromagnetic field. A modified theory of electromagnetic waves propagation in free space is offered.  Exact solutions of the nonlinear equations system in the presence of electric and gasdynamic interaction are obtained. Some of demonstrated exact solutions have a nature of continues and decretive spectrum.

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