Optical Properties of Mesoscopic Systems of Coupled MicrospheresShashaanka Ashili
Two mechanisms of optical coupling between spherical cavities, tight-binding between their whispering gallery modes and focusing produced by periodically coupled microlenses, are directly observed using spatially resolved scattering spectroscopy and imaging. The results can be used for developing device concepts of lasers, optical filters, microspectrometers and sensors based on mesoscopic systems of coupled microspheres.
DESIGN OF PRINTED MONOPOLE ANTENNA FOR MICROWAVE COMMUNICATIONjmicro
A printed monopole in its planar and vertical configuration has been designed, fabricated and analyzed
for microwave applications on low cost FR4 substrate material of thickness, h = 1.56 mm and relative
permittivity, εr = 4.3. The designed planar monopole has been simulated and experimented to find its
frequency response with coplanar waveguide feed to exhibit dual band characteristics with -10 dB
reflection loss bandwidth of 45.078 % (i.e. 1.5:1 between 1.334 and 2.109 GHz) and 114.92 % (i.e. 3.7: 1
between 3.99 and 14.77 GHz). The vertical monopole using the same patch has also been simulated and
experimented and -10 dB reflection loss bandwidth of 173.67% (14.2:1 between 0.925 and 13.125 GHz)
has been obtained. The antenna finds many applications in microwave bands.
PROXIMITY RING FED MULTIBAND PRINTED MONOPOLE FRACTAL ANTENNAjantjournal
Small antennas satisfying bandwidth requirements in wideband, broadband and multichannel
communication systems are of wide interest among researchers. This paper investigates the resonant
behaviour of proximity coupled circular fractal planar monopole against circular fractal planar monopole
without proximity coupling. The antennas are fed using microstripline and coplanar waveguide technique.
These antennas are designed and printed on low cost FR4 substrate ( height h=1.56mm and εr
=4.3) of size
110 mm by 115 mm with circular patch radius of 40 mm. The planar fractal monopole shows multiband
characteristics under different configurations of feed. The monopole can be used for various compact
applications in 482 MHz to 4 GHz band
MODELING STUDY OF LASER BEAM SCATTERING BY DEFECTS ON SEMICONDUCTOR WAFERSjmicro
Accurate modeling of light scattering from nanometer scale defects on Silicon wafersiscritical for enabling
increasingly shrinking semiconductor technology nodes of the future. Yet, such modeling of defect
scattering remains unsolved since existing modeling techniques fail to account for complex defect and
wafer geometries. Here, we present results of laser beam scattering from spherical and ellipsoidal
particles located on the surface of a silicon wafer. A commercially available electromagnetic field solver
(HFSS) was deployed on a multiprocessor cluster to obtain results with previously unknown accuracy
down to light scattering intensity of -170 dB. We compute three dimensional scattering patterns of silicon
nanospheres located on a semiconductor wafer for both perpendicular and parallel polarization and show
the effect of sphere size on scattering. We further computer scattering patterns of nanometer scale
ellipsoidal particles having different orientation angles and unveil the effects of ellipsoidal orientation on
scattering.
Optical Properties of Mesoscopic Systems of Coupled MicrospheresShashaanka Ashili
Two mechanisms of optical coupling between spherical cavities, tight-binding between their whispering gallery modes and focusing produced by periodically coupled microlenses, are directly observed using spatially resolved scattering spectroscopy and imaging. The results can be used for developing device concepts of lasers, optical filters, microspectrometers and sensors based on mesoscopic systems of coupled microspheres.
DESIGN OF PRINTED MONOPOLE ANTENNA FOR MICROWAVE COMMUNICATIONjmicro
A printed monopole in its planar and vertical configuration has been designed, fabricated and analyzed
for microwave applications on low cost FR4 substrate material of thickness, h = 1.56 mm and relative
permittivity, εr = 4.3. The designed planar monopole has been simulated and experimented to find its
frequency response with coplanar waveguide feed to exhibit dual band characteristics with -10 dB
reflection loss bandwidth of 45.078 % (i.e. 1.5:1 between 1.334 and 2.109 GHz) and 114.92 % (i.e. 3.7: 1
between 3.99 and 14.77 GHz). The vertical monopole using the same patch has also been simulated and
experimented and -10 dB reflection loss bandwidth of 173.67% (14.2:1 between 0.925 and 13.125 GHz)
has been obtained. The antenna finds many applications in microwave bands.
PROXIMITY RING FED MULTIBAND PRINTED MONOPOLE FRACTAL ANTENNAjantjournal
Small antennas satisfying bandwidth requirements in wideband, broadband and multichannel
communication systems are of wide interest among researchers. This paper investigates the resonant
behaviour of proximity coupled circular fractal planar monopole against circular fractal planar monopole
without proximity coupling. The antennas are fed using microstripline and coplanar waveguide technique.
These antennas are designed and printed on low cost FR4 substrate ( height h=1.56mm and εr
=4.3) of size
110 mm by 115 mm with circular patch radius of 40 mm. The planar fractal monopole shows multiband
characteristics under different configurations of feed. The monopole can be used for various compact
applications in 482 MHz to 4 GHz band
MODELING STUDY OF LASER BEAM SCATTERING BY DEFECTS ON SEMICONDUCTOR WAFERSjmicro
Accurate modeling of light scattering from nanometer scale defects on Silicon wafersiscritical for enabling
increasingly shrinking semiconductor technology nodes of the future. Yet, such modeling of defect
scattering remains unsolved since existing modeling techniques fail to account for complex defect and
wafer geometries. Here, we present results of laser beam scattering from spherical and ellipsoidal
particles located on the surface of a silicon wafer. A commercially available electromagnetic field solver
(HFSS) was deployed on a multiprocessor cluster to obtain results with previously unknown accuracy
down to light scattering intensity of -170 dB. We compute three dimensional scattering patterns of silicon
nanospheres located on a semiconductor wafer for both perpendicular and parallel polarization and show
the effect of sphere size on scattering. We further computer scattering patterns of nanometer scale
ellipsoidal particles having different orientation angles and unveil the effects of ellipsoidal orientation on
scattering.
NIR Three dimensional imaging of breast model using f-DOT Nagendra Babu
NIR three dimensional optical imaging of breast model using f-DOT using f-DOT with target specified contrast agent.
Three dimensional mathematical modeling of DOT,f-DOT.
Dispersion Properties of Photonic Crystal Fiber with Four cusped Hypocycloida...IOSRJECE
In this paper, dispersion characteristics of Photonic crystal fiber with four cusped hypocycloidal airhole in cladding (FCH-PCF) are investigated by using fully vectorial effective index method. Computed results show that the dispersion dependence on geometric parameters such as the hole pitch and size parameter. We find the flattened dispersion and zero dispersion wavelengths
Design of a Selective Filter based on 2D Photonic Crystals Materials IJECEIAES
Two dimensional finite differences temporal domain (2D-FDTD) numerical simulations are performed in cartesian coordinate system to determine the dispersion diagrams of transverse electric (TE) of a two-dimension photonic crystal (PC) with triangular lattice. The aim of this work is to design a filter with maximum spectral response close to the frequency 1.55 μm. To achieve this frequency, selective filters PC are formed by combination of three waveguides W 1 K A wherein the air holes have of different normalized radii respectively r 1 /a=0.44, r 2 /a=0.288 and r /a= 0.3292 (a: is the periodicity of the lattice with value 0.48 μm). Best response is obtained when we insert three small cylindrical cavities (with normalized radius of 0.17) between the two half-planes of photonic crystal strong lateral confinement.
In this paper we discuss the speckle reduction in images with the recently proposed Wavelet Embedded Anisotropic Diffusion (WEAD) and Wavelet Embedded Complex Diffusion (WECD). Both these methods are improvements over anisotropic and complex diffusion by adding wavelet based bayes shrink in its second stage. Both WEAD and WECD produce excellent results when compared with the existing speckle reduction filters.
NIR Three dimensional imaging of breast model using f-DOT Nagendra Babu
NIR three dimensional optical imaging of breast model using f-DOT using f-DOT with target specified contrast agent.
Three dimensional mathematical modeling of DOT,f-DOT.
Dispersion Properties of Photonic Crystal Fiber with Four cusped Hypocycloida...IOSRJECE
In this paper, dispersion characteristics of Photonic crystal fiber with four cusped hypocycloidal airhole in cladding (FCH-PCF) are investigated by using fully vectorial effective index method. Computed results show that the dispersion dependence on geometric parameters such as the hole pitch and size parameter. We find the flattened dispersion and zero dispersion wavelengths
Design of a Selective Filter based on 2D Photonic Crystals Materials IJECEIAES
Two dimensional finite differences temporal domain (2D-FDTD) numerical simulations are performed in cartesian coordinate system to determine the dispersion diagrams of transverse electric (TE) of a two-dimension photonic crystal (PC) with triangular lattice. The aim of this work is to design a filter with maximum spectral response close to the frequency 1.55 μm. To achieve this frequency, selective filters PC are formed by combination of three waveguides W 1 K A wherein the air holes have of different normalized radii respectively r 1 /a=0.44, r 2 /a=0.288 and r /a= 0.3292 (a: is the periodicity of the lattice with value 0.48 μm). Best response is obtained when we insert three small cylindrical cavities (with normalized radius of 0.17) between the two half-planes of photonic crystal strong lateral confinement.
In this paper we discuss the speckle reduction in images with the recently proposed Wavelet Embedded Anisotropic Diffusion (WEAD) and Wavelet Embedded Complex Diffusion (WECD). Both these methods are improvements over anisotropic and complex diffusion by adding wavelet based bayes shrink in its second stage. Both WEAD and WECD produce excellent results when compared with the existing speckle reduction filters.
Study the effect of thin film thickness on the optical features of (IR5 laser...TELKOMNIKA JOURNAL
The linear optical features such as (transmittance T, absorbance A, the effective length 퐿푒푓푓, absorption coefficient 훼 and refractive index 푛 ) for the thin films samples of (3x10-3 mol/l of (IR5) laser dye, 0.02 gm of (CdS) nanoparticles and 0.04 gm of pp polymer) had been studied at different values of film thickness in one time and at different number of Yb:GdVO4 laser pulses. The non-linear optical features in terms of transmittance difference Δ푇푝−푣, non-linear refractive index 푛2, non–linear phase shift Δ훷표 non-linear absorption coefficient 훽 and minimum normalized transmittance 푇(푍) have been computed in relation to obtained normalized transmittance data from setup of Z-scan with open and closed apertures, calculated for (3x10-3 mol/l of (IR5) laser dye, 0.02 gm of (CdSe) nanoparticles and 0.04 gm of (pp) polymer) thin films at different values of film thickness at in one time and at different Yb:GdVO4 laser pulses. Thick films causes in deleting the non-linear effects generated by different layers. The (CdSe) nanoparticles leads to an absorption shifting of the wavelengths to lengthier wavelengths of red shift. So, this can be used in selecting the nanoparticles and medium with applicable exciting wavelengths. The film thickness and the laser pulses have the main effects in consolidating the Non-linear optical features.
MODELING STUDY OF LASER BEAM SCATTERING BY DEFECTS ON SEMICONDUCTOR WAFERSjmicro
Accurate modeling of light scattering from nanometer scale defects on Silicon wafersiscritical for enabling
increasingly shrinking semiconductor technology nodes of the future. Yet, such modeling of defect
scattering remains unsolved since existing modeling techniques fail to account for complex defect and
wafer geometries. Here, we present results of laser beam scattering from spherical and ellipsoidal
particles located on the surface of a silicon wafer. A commercially available electromagnetic field solver
(HFSS) was deployed on a multiprocessor cluster to obtain results with previously unknown accuracy
down to light scattering intensity of -170 dB. We compute three dimensional scattering patterns of silicon
nanospheres located on a semiconductor wafer for both perpendicular and parallel polarization and show
the effect of sphere size on scattering. We further computer scattering patterns of nanometer scale
ellipsoidal particles having different orientation angles and unveil the effects of ellipsoidal orientation on
scattering.
Dr Jian Zhong - Modelling the neighbourhood-scale dispersion of ultrafine par...IES / IAQM
An unapologetically technical conference, DMUG remains the key annual event for experts in this field. Unmissable speakers will be examining topical issues in emissions, exposure and dispersion modelling.
Signal Degradation In Optical Fiber
Losses in an optical fibre:-
The types of losses in a optical fibre are
Attenuation loss
Absorption
Scattering
Bending loss
Dispersion loss
Coupling loss
Frequency-Dependent Squeezing for Advanced LIGOSérgio Sacani
The first detection of gravitational waves by the Laser Interferometer Gravitational-wave
Observatory (LIGO) in 2015 launched the era of gravitational wave astronomy. The quest for
gravitational wave signals from objects that are fainter or farther away impels technological advances
to realize ever more sensitive detectors. Since 2019, one advanced technique, the injection of squeezed
states of light is being used to improve the shot noise limit to the sensitivity of the Advanced LIGO
detectors, at frequencies above ∼ 50 Hz. Below this frequency, quantum back action, in the form of
radiation pressure induced motion of the mirrors, degrades the sensitivity. To simultaneously reduce
shot noise at high frequencies and quantum radiation pressure noise at low frequencies requires a
quantum noise filter cavity with low optical losses to rotate the squeezed quadrature as a function of
frequency. We report on the observation of frequency-dependent squeezed quadrature rotation with
rotation frequency of 30 Hz, using a 16 m long filter cavity. A novel control scheme is developed for
this frequency-dependent squeezed vacuum source, and the results presented here demonstrate that
a low-loss filter cavity can achieve the squeezed quadrature rotation necessary for the next planned
upgrade to Advanced LIGO, known as “A+.”
DEVELOPMENT OF OPTICAL PARAMETER CALCULATIONS OF THE PROBES IN WATERDr. Ved Nath Jha
Fiber optic technology with the role of surface plasmons has tremendously advanced the sensing technique of various physical, chemical and biochemical parameters of materials. The working of the optical fiber sensor designed by us is founded on the principle of the absorption of the evanescent waves passing through the optical fiber. The technique is based on the evanescent wave penetration between two dielectric media satisfying the conditions of attenuated total internal reflections (ATR’s). In the present work, the cladding of the fiber is removed by a suitable technique, and Silver nanoparticles are deposited on it. The evanescent light waves passing out of the core of the fiber are absorbed by the metal nanoparticles. The wavelength of maximum absorption is specific to the metal nanoparticles as well as to the dielectric constant of the surrounding medium and occurs when the wavelength of evanescent light resonates with localized surface plasmon (LSP) wavelength of the nanoparticle. Noble metal nanoparticles of Silver and Gold exhibit LSP resonance in the visible region of electromagnetic spectrum. In this article, we report the characteristic parameters of three sensor probes a, b and c developed by researcher.
3. What is a speckle correlation function? λ = 532 nm, C=1 λ = 633 nm, C=0
4. What is a speckle correlation function? λ = 532 nm, C=1 λ = 633 nm, C=0 Averaged change of speckle pattern as a function of wavelength or angle
5. The traditional speckle correlation function 3D medium: slab of strongly scattering particles PRL 64, 2788 (1990)
6. The traditional speckle correlation function 3D medium: slab of strongly scattering particles PRL 64, 2788 (1990) Compared to the complexity of the disorder the correlation function is simple
8. A surface plasmon polariton (SPP) Image from: Nature 424, 824 (2004) Surface wave Suffers from absorption, propagates typically 10-50 µm Subwavelength holes excite surface plasmons
9. Surface plasmons in ordered systems - holes excite surface plasmons - direct transmission - More than ten years of research to understand and apply extraordinary optical transmission Nature 391, 667 (1998)
10. Surface plasmons in ordered systems - holes excite surface plasmons - direct transmission - More than ten years of research to understand and apply extraordinary optical transmission Nature 391, 667 (1998) Compared to the simplicity of the structure the understanding the transmission spectrum is complicated
11. How to apply correlation functions to surface plasmons? Interesting and new: two transmission processes, direct (black) and surface plasmon assisted (red)
12. Are speckles seen in transmission? Very faint speckle pattern Intensity normalized to peak transmission OL 36, 3666 (2011)
24. Correlation width can be separated in scattering and absorption Scattering reduces the propagation length by a factor 5 Measured cross section is roughly a fifth of the hole diameter Absorption agrees with theory
25. The plasmon contribution vanishes at low density One parameter fit describes data Last data point deviates again. Deviations from model are expected at high densities (hole per squared wavelength).