Normalized Field Intensity Research Articles

Electromagnetic beam transmission in a uniaxial anisotropic slab with arbitrary optical axis

Based on the electromagnetic fields expansions over rectangular vector wave functions or eigen plane waves, the reflection and refraction of an electromagnetic beam by a uniaxial anisotropic slab are analyzed. The unknown expansion coefficients are determined from a system of linear equations derived by using the boundary conditions. In the uniaxial anisotropic slab, the optical axis is arbitrarily oriented with respect to the interface. As two typical examples, the normalized field intensity distributions are evaluated for a Gaussian beam and Hermite-Gaussian beam, and the propagation features are discussed briefly.

Electromagnetic wave beam propagation through a chiral slab

A general scheme for investigating the electromagnetic wave beam reflection by and transmission through a chiral slab is proposed. The electromagnetic wave beams within different regions are described by appropriate cylindrical vector wave function expansions, and their expansion coefficients are determined by using the boundary conditions and projection method. Under illumination by a fundamental Gaussian beam, a Hermite–Gaussian beam and a doughnut mode beam, numerical results of the normalized field intensity distributions are provided and discussed briefly.

Electromagnetic beam propagation through a gyrotropic anisotropic circular cylinder

A general scheme is proposed for investigating the propagation of an incident electromagnetic beam through a gyrotropic anisotropic circular cylinder. The electromagnetic fields in different regions are expanded in terms of appropriate cylindrical vector wave functions, and the unknown expansion coefficients are determined by using the boundary conditions and projection scheme. For incidence of a fundamental Gaussian beam, Hermite–Gaussian beam and zero-order Bessel beam, normalized field intensity distributions are evaluated and discussed briefly.

Propagation of shaped beam through uniaxially anisotropic chiral slab* *Project supported by the National Natural Science Foundation of China (Grant No. 61771385), the Science Foundation for Distinguished Young Scholars of Shaanxi Province, China (Grant No. 2020JC-42), the Fund from the Science and Technology on Solid-State Laser Laboratory, China (Grant No. 6142404180301), and the Science and Technology Research Plan of Xi’an

A general solution is obtained to a canonical problem of the reflection and refraction of an arbitrary shaped beam by using a uniaxially anisotropic chiral slab. The reflected, internal as well as refracted shaped beams are expanded in terms of cylindrical vector wave functions, and the expansion coefficients are determined by using the boundary conditions and method of moments procedure. As two typical examples, the normalized field intensity distributions are evaluated for a fundamental Gaussian beam and Hermite–Gaussian beam, and some propagation properties, especially the negative refraction phenomenon, are discussed briefly.

Gaussian beam scattering by an infinite cylinder with a spherical inclusion

An analytical method of analyzing the electromagnetic scattering of a Gaussian beam by an infinitely long circular cylinder with a spherical inclusion is presented. The fields within different regions are expanded in terms of appropriate cylindrical or spherical vector wave functions. By applying the integral representation of spherical vector wave functions over cylindrical ones, boundary conditions and projection procedure, the unknown expansion coefficients are determined. For a localized beam model, numerical results of the total scattered field and normalized field intensity distribution are shown, and the scattering properties are discussed briefly.

Propagation of light beam through a uniaxially anisotropic chiral cylinder

A general scheme is proposed for investigating a canonical problem of light beam scattering by a uniaxially anisotropic chiral cylinder. The light beams within different regions are expanded in terms of appropriate cylindrical vector wave functions, and their expansion coefficients are determined by using the boundary conditions and projection method. For incidence of a fundamental Gaussian beam and Hermite–Gaussian beam, numerical results of normalized field intensity distributions are provided and discussed briefly.

A new method for path-loss modeling

AbstractIn this paper, a new path-loss model for electromagnetic wave in an indoor multipath environment is proposed based on matching coefficient, polarization matching factor, and normalized field intensity direction function. This model is called the Friis-extension (Friis-EXT) model, because it operates as the Friis model under certain conditions. In addition, in the modeling process of the path-loss in an indoor environment, the reflective surfaces in the environment and form of the antenna are considered. Afterwards, the path-loss data in an indoor corridor environment are measured, and the maximum error between the theoretical value and the measured data is <7.5 dB. Finally, the Friis-EXT model is compared with some other traditional models, and the results show that the Friis-EXT model is the best one that matches the measurement data.

Transmission of electromagnetic beam through a uniaxial anisotropic slab

We present a general theoretical scheme to investigate the propagation characteristics of a focused electromagnetic beam in a uniaxial anisotropic slab. The reflected, internal as well as transmitted waves are expanded in terms of cylindrical vector wave functions, and the unknown expansion coefficients are determined by virtue of the boundary conditions and the projection method. For incidence of a fundamental Gaussian beam, Hermite–Gaussian beam and doughnut mode beam, normalized field intensity distributions are evaluated and discussed briefly.

Designing of convenient PCF structure for SERS applications

We investigated that the performance of side-channel photonic crystal fiber (SC-PCF) is controlled by the subtended angle of the liquid channel to the center point of the core (channel angle). This investigation is used for designing the SC-PCF to enhance the Surface Enhanced Raman Spectroscopy (SERS) signal. The deviation of the maximum normalized field intensity from the solid core center, and the mode field diameter change with the channel angle. We used finite element method (FEM) to obtain the normalized field intensity distributions, and a Gaussian approximation with position parameter is utilized to analyze them. The normalized field intensity on core liquid interface and the evanescent field ratio are considered to measure the performance. It is found that the performance is maximized when the channel angle is 90o at 632.8 nm of excitation wavelength. These results are very important for the sensing application in chemical, biomedical engineering and research fields.

Propagation of Gaussian beam through a uniaxial anisotropic slab

An exact analytical solution to the reflection and transmission of an incident Gaussian beam by a uniaxial anisotropic slab is obtained in terms of the rectangular vector wave function expansion form. In the uniaxial anisotropic slab, the optical axis is parallel to the interface. For a localized beam model, numerical results of the normalized field intensity distributions are presented, and the propagation characteristics are analyzed concisely.

Reflection and transmission of Gaussian beam by a chiral slab

Based on the generalized Lorenz–Mie theory framework, the reflection and transmission of an incident Gaussian beam by a chiral slab were investigated, by expanding the incident Gaussian beam, reflected beam, internal beam as well as transmitted beam in terms of cylindrical vector wave functions. The unknown expansion coefficients were determined by virtue of the boundary conditions. For a localized beam model, numerical results of the normalized field intensity distributions are presented, and the propagation characteristics are discussed concisely in this paper.

Transmission of Gaussian beam through a coated chiral cylinder

Based on the generalized Lorenz–Mie theory (GLMT) framework, an exact analytical solution to the transmission of a Gaussian beam through a chiral cylinder with dielectric coating is formulated, by expanding the incident Gaussian beam, internal beam as well as scattered beam in terms of cylindrical vector wave functions (CVWFs). The unknown expansion coefficients are determined by a system of equations derived from the boundary conditions. For a localized beam model, numerical results of the normalized field intensity distributions are presented, and the propagation characteristics are discussed concisely.

Reflection and transmission of Gaussian beam by a uniaxial anisotropic slab

The reflection and transmission of an incident Gaussian beam by a uniaxial anisotropic slab are investigated, by expanding the incident Gaussian beam, reflected beam, internal beam as well as transmitted beam in terms of cylindrical vector wave functions. The unknown expansion coefficients are determined by virtue of the boundary conditions. For a localized beam model, numerical results are provided for the normalized field intensity distributions, and the propagation characteristics are discussed concisely.

Coherent x-ray scattering from ultrathin probe layers

We have studied x-ray grazing incidence reflection from ultrathin layers that are embedded in thin film systems. This technique can be applied to selectively probe the properties of stratified media as a function of depth. A remarkable coherent enhancement of the reflected intensity renders this technique sensitive to ultrathin layers in the monolayer range. We investigate this enhancement theoretically and show that the coherently scattered signal is proportional to the square of the normalized field intensity at the position of the probe layer. This is in contrast to incoherent scattering from such probe layers where the signal scales linearly with the normalized field intensity at the position of the probe layer. The coherent enhancement is investigated experimentally by nuclear resonant scattering of synchrotron radiation from ultrathin isotopic layers of $^{57}\mathrm{Fe}$. The technique can be applied to all fields of coherent x-ray scattering from thin films.

Bending loss evaluation of single-mode fibres with arbitrary core index profile by far-field pattern

An evaluation of the bending loss of single-mode fibers based on the measured mode field is described. The field decay constant and the normalized field intensity in the cladding are determined. Experimental results verified the validity of this method. Its accuracy is determined by the accuracy of field measurement. The mode field is calculated from the far-field distribution measured with finite dynamic range of more than 50 dB. Far-field measurement with finite dynamic range limits the accuracy of field evaluation. Dispersion shifted fibers are easier for evaluation because of the wider far-field distribution. Bending loss and mode field diameter can be measured simultaneously, and the method is applicable to any single-mode fibers with a matched clad structure. A microbending loss formula is also determined by the decay constant and the normalized field intensity in the cladding as well as uniform bending loss.

The flow of conducting fluids in circular pipes under transverse magnetic fields

The flow rate of liquid metals is commonly measured by electromagnetic flowmeters. In these the fluid moves through a region of transverse magnetic field, inducing a potential difference between two electrodes on the walls of the pipe. The ratio of signal to flow rate is dependent on the velocity profile, and this is affected by electromagnetic forces.In this paper the ultimate steady velocity profile and its associated pressure gradient and induced potential are calculated for the case of laminar flow in a circular pipe whose walls are conducting but without contact resistance. Laminar flow is encouraged by a transverse field. When the fluid conductivity and field strength are sufficiently high, boundary layers occur with a thickness inversely proportional to normal field intensity. The induced potential difference is then 0·926 of the value corresponding to the case of uniform velocity if the walls are non-conducting.The distance the fluid must travel after entering the transverse field before the steady state is reached is next estimated by a Rayleigh approximation. The inlet velocity is taken to be uniform and effects which occur at the edge of the field are neglected. The process falls into two stages, first a boundary-layer growth and then an adjustment of the velocity away from the walls, occupying a much greater length of pipe. The entry length is shorter than it is in the case of flow in a rectangular pipe, but is still too long for appreciable distortion of the velocity profile to occur within practical flowmeters except at low flow rates. The pressure drop associated with the adjustment of the velocity profile is found to be independent of field strength, if this is high, and about one-eighth of the drop which occurs in the non-conducting case.Experiments are described in which steady-state pressure gradients and induced potential differences were measured in mercury flowing along Perspex pipes of 0·5 and 0·25 in. bore in transverse fields up to 14500 gauss. The results confirmed the steady-state theory within the limitations of experimental accuracy and the assumption in the theory of high conductivity and an intense field. The experiments also covered the entry region in many cases, and showed that the theoretical entry lengths were correct in order of magnitude but over-estimated. However, the exact entry condition was uncertain, and steady readings were difficult to obtain in the entry region.