Photoelastic Waveguides In Sige/Si Heterostructures And Bulk Si

1997 ◽  
Vol 486 ◽  
Author(s):  
E. Lea ◽  
B. L. Weiss ◽  
H. Rho ◽  
H. E. Jackson
Keyword(s):  
Transverse Strain ◽  
Bulk Silicon ◽  
Low Loss ◽  
Good Agreement

AbstractPhotoelastic waveguides in bulk Si and SiGe/Si heterostructures have been modelled and characterised. The calculated transverse strain profiles of photoelastic waveguide structures in SiGe/Si heterostructures and bulk silicon are in good agreement with those obtained by microRaman experiments. The waveguide characteristics are also found to be in good agreement with those obtained from the strain modelling and demonstrate that low loss waveguides can be fabricated using these structures

Silver Nanocrystals at Cavities Created by High Energy Helium Implantation in Bulk Silicon

2007 ◽  
Vol 994 ◽  
Author(s):  
Rachid El Bouayadi ◽  
Gabrielle Regula ◽  
Maryse Lancin ◽  
Eduardo Larios ◽  
Bernard Pichaud ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Energy ◽  
Nickel Silicide ◽  
Bulk Silicon ◽  
Shape Characteristic ◽  
Transmission Electron ◽  
Helium Implantation ◽  
Ag Deposition ◽  
First Time ◽  
Good Agreement

AbstractHigh resolution transmission electron microscopy observations show for the first time the presence of two orientations of pure silver precipitates in nanocavities induced in bulk silicon by implantation at 1.6 MeV with a dose of 5×1016 He+ cm−2 and a two hour annealing at 1050°C. These precipitates were called A and B to refer to the two well-known nickel silicide (NiSi2) precipitates or Ag films on a {111} silicon surface. Thus, the A precipitate corresponds to a growth of silver nanocrystal on {111} cavity walls in epitaxy with the Si matrix with an orientation relationship Ag(-111)[211]||Si(-111)[211]. The B precipitate develops on a {111} plane parallel to a {111} cavity wall as well, but in a twin orientation with respect to the Si matrix defined by Ag(-111)[211]||Si(-111)[-2-1-1]. The Ag nanocrystals have a size ranging from a few nm to 50 nm. Most of them have the faceted-shape characteristic of “clean” cavities. They are either A precipitates or they contain alternatively A and B bands in good agreement with both the low stacking fault energy of silver and the two types of nanocrystal orientations obtained by Ag deposition on (111) Si substrate at room temperature. Some Ag precipitates were also found at dislocations located at the He+ projection range, but these trapping sites were found thermally unstable as compared to the cavity ones. Indeed, during a second identical annealing, the precipitates grow in cavities whereas they fade at dislocations.

Electronic Structure of YFe2 by EELS and Ab Initio Calculations

2009 ◽  
Vol 68 ◽  
pp. 89-95 ◽  
Author(s):  
Emilio Yáñez-Terrazas ◽  
Veronica Gallegos-Orozco ◽  
José Andrés Matutes-Aquino ◽  
Martha T. Ochoa-Lara ◽  
Francisco Espinosa-Magaña
Keyword(s):  
Local Spin Density Approximation ◽  
Density Approximation ◽  
Interband Transitions ◽  
Low Loss ◽  
Augmented Plane Wave ◽  
Transmission Electron ◽  
Phase Compound ◽  
Flapw Method ◽  
Linearized Augmented Plane Wave ◽  
Good Agreement

The dielectric properties of the intermetallic cubic Laves phase compound YFe2 were determined by analyzing the low loss region of the EELS spectrum in a transmission electron microscope. From these data, the optical joint density of states (OJDS) was obtained by Kramers-Kronig analysis. Since maxima observed in the OJDS spectra are assigned to interband transitions; these spectra can be interpreted on the basis of numerical calculations performed with the Wien2k code, using the Fully-Linearized-Augmented-Plane wave (FLAPW) method within the Local-Spin-Density Approximation. Comparison between experimental results and theory shows good agreement.

Admittance of an infinite cylindrical antenna immersed in a lossy, compressible plasma

1969 ◽  
Vol 47 (20) ◽  
pp. 2129-2135 ◽  
Author(s):  
Richard L. Monroe
Keyword(s):  
Plasma Frequency ◽  
Propagation Constant ◽  
Plasma Temperature ◽  
Particle Collision ◽  
Low Loss ◽  
Compressible Plasma ◽  
Cylindrical Antenna ◽  
Electroacoustic Wave ◽  
Gap Width ◽  
Good Agreement

An expression is derived for the driving point admittance of an infinite, perfectly conducting cylindrical antenna excited by a finite uniform gap and immersed in a lossy, compressible, isotropic plasma. This expression is based on the twin assumptions that the gap width is much smaller than the wavelength of the plasma (electroacoustic) wave and that the radius of the antenna is much smaller than the wavelength of the electromagnetic wave; it is similar in form to the corresponding expression for an infinite antenna in free space, and it is obtained in much the same manner. Conductance and susceptance curves computed from the admittance function are in good agreement with those obtained numerically by other authors for f ≥ 0.7 fP. The behavior of the admittance function at frequencies in the neighborhood of the plasma frequency depends mainly on the electron – neutral particle collision frequency, not the plasma temperature. In general, the effect of the temperature is quite small, although a temperature-related effect can produce large admittance values in very low-loss plasmas at frequencies well below the plasma frequency (f ~ 0.03 fP for T = 1500 °K). This investigation supports the view that the propagation constant of the current along a cylindrical antenna in a compressible plasma is nearly equal to the plane-wave propagation constant in an incompressible plasma.

scholarly journals Integrated 2D graphene oxide layered films for enhanced nonlinear optics in high index doped silica waveguides

2021 ◽  
Author(s):  
David Moss
Keyword(s):  
Graphene Oxide ◽  
Silicon Nanowires ◽  
Nonlinear Optical ◽  
Kerr Nonlinearity ◽  
Four Wave Mixing ◽  
Photonic Devices ◽  
Wave Mixing ◽  
Low Loss ◽  
Strong Mode ◽  
Good Agreement

Abstract We demonstrate enhanced four-wave mixing (FWM) in doped silica waveguides integrated with graphene oxide (GO) layers. Owing to strong mode overlap between the integrated waveguides and GO films that have a high Kerr nonlinearity and low loss, the FWM efficiency of the hybrid integrated waveguides is significantly improved. We perform FWM measurements for different pump powers, wavelength detuning, GO coating lengths, and number of GO layers. Our experimental results show good agreement with theory, achieving up to ~9.5-dB enhancement in the FWM conversion efficiency for a 1.5-cm-long waveguide integrated with 2 layers of GO. We show theoretically that for different waveguide geometries an enhancement in FWM efficiency of ~ 20 dB can be obtained in the doped silica waveguides, and more than 30 dB in silicon nanowires and slot waveguides. This demonstrates the effectiveness of introducing GO films into integrated photonic devices in order to enhance the performance of nonlinear optical processes.

scholarly journals APL Photonics 2018 Invited Paper

2020 ◽  
Author(s):  
David Moss
Keyword(s):  
Graphene Oxide ◽  
Silicon Nanowires ◽  
Nonlinear Optical ◽  
Kerr Nonlinearity ◽  
Four Wave Mixing ◽  
Photonic Devices ◽  
Wave Mixing ◽  
Low Loss ◽  
Strong Mode ◽  
Good Agreement

We demonstrate enhanced four-wave mixing (FWM) in doped silica waveguides integrated with graphene oxide (GO) layers. Owing to strong mode overlap between the integrated waveguides and GO films that have a high Kerr nonlinearity and low loss, the FWM efficiency of the hybrid integrated waveguides is significantly improved. We perform FWM measurements for different pump powers, wavelength detuning, GO coating lengths, and number of GO layers. Our experimental results show good agreement with theory, achieving up to ~9.5-dB enhancement in the FWM conversion efficiency for a 1.5-cm-long waveguide integrated with 2 layers of GO. We show theoretically that for different waveguide geometries an enhancement in FWM efficiency of ~ 20 dB can be obtained in the doped silica waveguides, and more than 30 dB in silicon nanowires and slot waveguides. This demonstrates the effectiveness of introducing GO films into integrated photonic devices in order to enhance the performance of nonlinear optical processes.

scholarly journals Design of an Offset Posts K- band Bandpass Filter using Substrate Integrated Waveguide for Microwave Applications

2020 ◽  
Vol 8 (6) ◽  
pp. 1056-1058
Keyword(s):  
Bandpass Filter ◽  
Dielectric Material ◽  
Ground Plane ◽  
Center Frequency ◽  
Pass Band ◽  
Substrate Integrated Waveguide ◽  
Low Loss ◽  
Communication Devices ◽  
Good Agreement ◽  
K Band

In this paper, an offset posts K-band bandpass filter has been designed using substrate integrated waveguide (SIW). SIW is formed inside a dielectric material by applying a top metal over the ground plane and trapping the structure on either side with rows of plated vias. SIW is effective and efficient solution in waveguide technique. The slotted windows are cut in tapered transition of SIW filter to attain low loss. The proposed filters are designed at 23 GHz center frequency. The simulated results exhibit low losses and sharp roll off characteristics in pass band. There is good agreement between the simulated results and the experimental results. The proposed filter is suitable for use in microwave communication devices.

Creation of Solid Immersion Lenses in Bulk Silicon Using Focused Ion Beam Backside Editing Techniques

2008 ◽  
Author(s):  
P. Scholz ◽  
U. Kerst ◽  
C. Boit ◽  
C.-C. Tsao ◽  
T. Lundquist
Keyword(s):  
Optical Properties ◽  
Processing Time ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Milling Process ◽  
Field Of View ◽  
Bulk Silicon ◽  
Air Gaps ◽  
Lens Material ◽  
Good Agreement

Abstract This work describes how Solid Immersion Lenses (SILs) can be created in bulk silicon using a focused ion beam and a bitmap milling process. The optical properties are in good agreement with the expected results for the achieved lens geometries. An improvement in lateral spatial resolution by a factor of 1.8 and in image contrast by 170 % for backside analysis is demonstrated. The presented SILs are 32 µm in diameter with a field of view of about 10 μm. This process can be an alternative when a regular SIL placement on the chip is impossible or complex. The advantages of this method are the use of a single kind of material (no air gaps and no additional lens material with different n value), the ability to precisely position the SIL on the circuitry and the fact that a SIL may be created in less than twenty minutes of processing time.

GaAs Devices for Low Loss Power Rectification

1992 ◽  
Vol 281 ◽  
Author(s):  
L. V. Munukutla ◽  
S. H. Cheng ◽  
S. J. Anderson
Keyword(s):  
Barrier Height ◽  
Vapor Phase ◽  
High Voltage ◽  
Experimental Results ◽  
Low Loss ◽  
Barrier Heights ◽  
Schottky Rectifiers ◽  
Gaas Devices ◽  
Order Of Magnitude ◽  
Good Agreement

ABSTRACTHigh voltage GaAs Schottky rectifiers fabricated using vapor phase epitaxy have been observed to be an order of magnitude higher in switching speeds than silicon. Measured rectifier barrier heights deduced from the I-V and C-V plots were found to be in good agreement with previously reported values. Our experimental results show no correlation between the epilayer thickness and barrier height.

scholarly journals All-dielectric photonic metamaterials operating beyond the homogenization regime

2012 ◽  
Vol 1 (1) ◽  
pp. 6 ◽  
Author(s):  
K. V. Do ◽  
X. Le Roux ◽  
C. Caer ◽  
D. Morini ◽  
L. Vivien ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Frequency Region ◽  
Optical Measurements ◽  
Fdtd Simulation ◽  
Metallic Materials ◽  
Proof Of Concept ◽  
Low Loss ◽  
Unit Cells ◽  
Sub Wavelength ◽  
Good Agreement

Photonic metamaterials made of graded photonic crystals operating near the bandgap frequency region are proposed for field manipulation around l=1.5μm. Proof-of-concept structures have been studied using Hamiltonian optics and FDTD simulation, fabricated, and characterized using farfield optical measurements. Experimental results are in good agreement with predictions, showing the interest of graded photonic crystals as an (ultra-low loss) alternative solution to the use of metamaterials combining dielectric and metallic materials with sub-wavelength unit cells.

Oscillator Strength Measurements in the Vacuum-Ultraviolet by the Emission Method

1988 ◽  
Vol 102 ◽  
pp. 353-356
Author(s):  
C. Goldbach ◽  
G. Nollez
Keyword(s):  
Oscillator Strength ◽  
Vacuum Ultraviolet ◽  
Oscillator Strengths ◽  
Emission Method ◽  
Absolute Scale ◽  
Good Agreement

AbstractThe principles and the realization of an experiment devoted to oscillator strength measurements in the vacuum-ultraviolet by the emission method are briefly presented. The results obtained for the strong multiplets of neutral nitrogen and carbon in the 1200-2000 Å range yield an absolute scale of oscillator strengths in good agreement with the most recent calculations.

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