Effect Of Polarization Direction Research Articles

Effects of polarization direction, amplitude, and photon energy of linearly polarized laser on high order harmonic generation of C60

The study of high-order harmonic generation (HHG) in confined quantum systems is essential for developing a comprehensive physical description of harmonic generation from atoms to bulk solids. Using the time-dependent density-functional theory, we demonstrate how the symmetry of the system modulates the generation of high-order harmonic in fullerene C60 molecules along different orthogonal directions, as well as the effects of amplitude and photon energy of a linearly polarized laser on high-order harmonics generation. We found that the generation of high-order harmonics perpendicular to the laser polarization direction (LPD) is related to the symmetry of molecules along the LPD and the symmetry of molecules perpendicular to the LPD. Within a certain parameter range, the cut-off energy is linearly proportional to the laser amplitude and the laser photon energy.

Individually frequency and amplitude tunable metamaterial absorber with sensing functions based on strontium titanate and graphene

A terahertz metamaterial absorber with sensing function based on strontium titanate (STO) and graphene is designed. The optical characteristics of the designed structures are simulated and numerically calculated by the finite difference time domain (FDTD) and coupled mode theory (CMT) method. The results show that the temperature of STO is 300 K and Fermi level of graphene is 1.0 eV, the absorptance achieves 99.8 % and 92.7 % at 0.36 THz and 2.18 THz, respectively. When the temperature of the STO is set from 250 K to 400 K, the center frequency is moved from 0.32 THz and 1.96 THz to 0.43 THz and 2.54 THz. When the temperature is stable at 300 K, the dual narrow band absorption can be converted to single narrow band absorption by tuning the Fermi level from 1.0 eV to 0 eV. The physical mechanism of the dual narrow band absorptions and active tuning is analyzed by electric field distribution and impedance matching theory. The effect of polarization direction and incident angle on the absorber performance is also investigated. In addition, we also investigated the sensing characteristics of the absorber when the Fermi level of graphene is 0 eV, and the sensitivity and figure of meritis of the structure for detecting different refractive indices is 50 GHz/RIU and 0.33/RIU. The proposed structure provides new ideas for future multifunctional terahertz device design.

Effects of polarization direction on removal characteristics of silver nanowire transparent conductive film by ultrashort pulsed laser

Effects of polarization direction on removal characteristics of silver nanowire transparent conductive film by ultrashort pulsed laser

Excitonic and fluorination effects on optoelectronic response of GeC hybrid

Using GW approximation + Bethe-Salpeter equation, we study optical and electronic responses of three fluorinated structures of GeC namely, F-GeC-F, F-GeC and GeC-F and compare our results with other fluorinated 2D materials. The absence of soft modes demonstrates stability of the three structures. The band gaps were determined in presence and absence of quasiparticle correction. The results show that fluorination tunes the gap but its nature remains the same. Effect of polarization direction and local field on imaginary part of macroscopic dielectric function were also reported. Optical properties investigated through analysing absorption spectra reveals a weak electron-hole interaction for GeC-F where Bohr radius of exciton is 8.64 Å. However, a strong electron-hole interaction in the two others fluorinated structures leads to the appearance of small radius of excitons with spatially separated electron and hole, which are localized out of plane and in plane, respectively. The presence of such bounded excitons in the studied structures makes them good candidates for optoelectronic applications and quantum information technologies.

Effects of Polarization Direction on Removal Characteristics of Silver Nanowire Transparent Conductive Film by fs Pulsed Laser

Silver nanowire transparent conductive film is expected as a new material for transparent electrodes because of its superior flexibility and electrical conductivity with high transparency at visible wavelength. Laser beam processing has been widely used for these application, and laser beam has the unique characteristic as an electromagnetic wave. Its feature has a great influence on laser-material interaction. However, these mechanism have not yet been clarified. Therefore, the polarization characteristics indicated by electric and magnetic fields were discussed, and effects of polarization direction on removal characteristics of silver nanowire transparent conductive film were investigated by using femtosecond pulsed laser with linear polarization.

Effects of polarization direction on laser-assisted free–free scattering

This work will detail the effects of laser polarization direction (relative to the momentum transfer direction) on laser-assisted free–free scattering. Such processes play a role in the gas breakdown that occurs in electric discharges as well as providing a method for the laser heating of a plasma (Musa et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 175201, Mason 1993 Rep. Prog. Phys. 56 1275). Experimental results will be presented for electron-helium scattering in the presence of an Nd:YAG laser field ( eV) where the polarization direction was varied in a plane that is perpendicular to the scattering plane. To date, all of our experimental results are well described by the Kroll–Watson approximation (KWA) (Kroll and Watson 1973 Phys. Rev. A 8 804). The good agreement between our experiments and calculations using the KWA includes the case where the polarization is perpendicular to the momentum transfer direction, for which the KWA predicts vanishing cross section; other workers have found that the KWA tends to be inaccurate for cases where it predicts small cross sections (e.g. Musa et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 175201). We also present simulations of the effects that multiple scattering might have on experimental measurements. In particular, we examine conditions that are expected to be similar to those of the experiments reported by Wallbank and Holmes (Wallbank and Holmes 1993 Phys. Rev. A 48 R2515).

Eletron-helium laser-assisted free-free scattering for incident energies from 30 - 200 eV: effects of polarization direction

SynopsisWe report on experiments that examine electron-helium scattering in the presence of an Nd:YAG laser field of 1.17 eV photons. At each incidentelectron energy (30, 60, and 200 eV), the laser polarization direction is varied within a plane perpendicular to the Watson approximation calculations.

Vibroacoustic response and active control of a fluid-filled functionally graded piezoelectric material composite cylinder

The linear three-dimensional piezoelasticity theory in conjunction with the versatile transfer matrix approach is employed to investigate the steady-state nonaxisymmetric fluid–structure-coupled vibrations of an arbitrarily thick bilaminate simply supported hollow cylinder of finite length, composed of an inner layer of orthotropic functionally graded material perfectly bonded to an outer layer of radially/axially/circumferentially polarized functionally graded piezoceramic material. The cylinder is filled with a compressible nonviscous fluid and may be subjected to arbitrary time-harmonic on-surface mechanical drives. The analytical results are illustrated with numerical examples in which water-filled homogeneous PZT4–steel composite cylinders are driven by harmonic external concentrated or distributed radial surface loads. When the outer piezoelectric layer is operating in the receiving (sensing) mode, the frequency spectrums of the induced voltage, stress components, and on-axis acoustic pressure are calculated and discussed for the selected loading configurations. Also, when the piezolayer operates in the active vibration mode, the effects of polarization direction and number of control modes on the voltage required for partial or complete cancellation of the on-axis internal pressure are investigated. Limiting cases are considered, and the validity of results is established by comparison with the data in the existing literature as well as with the aid of a commercial finite element package.

电场极化方向对自由空间电场测量的影响

电场极化方向对自由空间电场测量的影响

Forward scattering light of droplets containing different size inclusions

Scattering by a sphere with a different internal structure has drawn attention. The forward scattering light of a water droplet containing multiple different size carbon inclusions is calculated by the finite-difference time-domain method. Herein, distribution of these carbon inclusions conforms to Apollonian packing in a droplet. The space left over between carbon inclusions constructs a fractal, of which the fractal dimension D is expressed as D approximately 1.305684. The incident wave is in the y-direction polarization. The results show that the amplitude of the intensity fluctuations is not associated with the fractal dimension. Carbon inclusions only decrease the component y of electric field intensity at the place of inclusions. For a droplet containing multiple concentrated inclusions with different sizes, the amplitude of the intensity fluctuations is related with every space between inclusions. And the far field light intensity approaches the intensity caused by one carbon inclusion as space between inclusions becomes less and less. In order to know the effect of polarization direction, transmissibility versus theta(angle between the polarization direction of the incident wave used and the y-axis direction) is finally obtained. It can be seen that the transmissibility changes with theta conformably and reaches a minimum when theta = 30 degrees. Transmissibility is equal for theta = 90 degrees and theta = 0 degrees.

Structural Design of Piezoelectric Actuator Considering Polarization Direction and Continuous Approximation of Material Distribution

In the design of piezoelectric actuator the concept of compliant mechanism combined with piezoelectric materials has been used to magnify either geometric or mechanical advantage. The polarization of piezoelectric materials is considered to improve actuation since the piezoelectric polarization has influences on the performance of the actuator. The topology design of compliant mechanism can be formulated as an optimization problem of material distribution in a fixed design domain and continuous approximation of material distribution(CAMD) method has demonstrated its effectiveness to prevent the numerical instabilities in topology optimization. The optimization problem is formulated to maximize the mean transduction ratio subject to the total volume constraints and solved using a sequential linear programming algorithm. The performance improvement of Moonie actuator design confirms an effect of polarization direction and CAMD.