Gravitational lensing of charged Ayon-Beato-Garcia black holes and non-linear effects of Maxwell fields

Non-singular Ayon-Beato-Garcia (ABG) spherically symmetric static black hole (BH) with charge to mass ratio $q$ is metric solution of Born-Infeld nonlinear Maxwell-Einstein theory. Central region of the BH behaves as (anti-) de Sitter for $(|q|>1)~|q|<1 .$ In case of $|q|=1$ the BH central region behaves as Minkowski flat metric. Nonlinear Electromagnetic (NEM) fields counterpart causes to deviate light geodesics and so light rays will forced to move on effective metric. In this paper we study weak and strong gravitational lensing of light rays by seeking affects of NEM fields counterpart on image locations and corresponding magnification. We set our calculations to experimentally observed Sgr A$^*$ BH. In short we obtained: For large distances the NEM counterpart is negligible reaching to linear Maxwell fields. The NEM makes enlarge the BH photon sphere radius as linearly by raising $|q|>1$ but deceases by raising $|q|\leq1.$ Sign of deflection angle of bending light rays is changed in presence of NEM effects with respect to ones obtained in absence of NEM fields. Absolute value of deflection angle raises by increasing $|q|\to1.$ Weak image locations decreases (increases) by raising $0<|q|<1$ in presence (absence) of NEM fields. By raising the closest distance of the bending light rays weak image locations changes from left (right) to right (left) in absence (presence) of NEM fields. Einstein rings radius and corresponding Magnification centroid become larger (smaller) in presence (absence) of NEM fields in case of weak lensing. Angular separation $s$ between the innermost and outermost relativistic images increases (decreases) by increasing $0<|q|<1$ in absence (presence) of NEM fields. Corresponding magnification $r$ decreases (increases) by raising $0<|q|<1$ in absence (presence) of NEM fields. $s (r)$ raises (decreases) by increasing $|q|>>1.$Comment: 36 Pages, 7 Figures and 2 Tabl

Structuring light under different polarization states within micrometer domains: exact analysis from the Maxwell equations

We show the possibility of arbitrary longitudinal spatial modeling of non-diffracting light beams over micrometric regions. The resulting beams, which are highly non-paraxial, possess subwavelength spots and can acquire multiple intensity peaks at predefined locations over regions that are few times larger than the wavelength. The formulation we present here provides exact solutions to the Maxwell's equations where the linear, radial, and azimuthal beam polarizations are all considered. Modeling the longitudinal intensity pattern at small scale can address many challenges in three-dimensional optical trapping and micromanipulation.2591005110056CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP304718/2016-52015/26444-8; 2016/11174-

Compact and broadband polarization beam splitter based on a silicon nitride augmented low-index guiding structure

We propose a compact polarization beam splitter (PBS) based on a silicon nitride enhanced silicon-on-insulator platform using an augmented low-index guiding (ALIG) waveguide structure. In the ALIG structure, the TM mode is mostly confined in the low-index silicon nitride, while the TE mode is confined in the high-index silicon. Since the two modes are confined in two separate layers, their properties can be controlled independently. The PBS is formed using an asymmetric multimode interference (MMI) section. The TM mode is directed to an output port by the ALIG waveguide, while the TE mode is coupled to the other output port via the multimode interferometer. Such a PBS has a very small footprint, low insertion loss, high polarization extinction ratio, and broadband response

Polarization rotator based on augmented low-index-guiding waveguide on silicon nitride/silicon-on-insulator platform

Using a newly proposed augmented low-index-guiding scheme with silicon nitride/silicon dual-core waveguide, we have designed, fabricated, and characterized a transverse electric (TE) to transverse magnetic (TM) and TM-to-TE compact polarization rotator. The polarization rotation is realized in an asymmetric directional coupler. The measured peak conversion efficiencies for the TE-to-TM and TM-to-TE rotations are approximately 97%. The measured polarization extinction ratio for the TE-to-TM rotation is greater than 20 dB over 50-nm bandwidth, while for the TM-to-TE rotation it is greater than 15 dB over the C-band

Highly Efficient Excitation of Surface Plasmons Using a Si Gable Tip

A compact and highly efficient technique to excite SPP mode at an Au/SiO2 interface by using an engineered high index (silicon) gabled tip at the 1550 nm wavelength has been proposed. The optimized geometry of the Si tip enables a highly efficient excitation of the single interface SPP mode through near field interaction in an ultra-compact setup. An experimental demonstration of the proposed scheme is also presented in the paper which converts 25.5% of the total input power to an SPP mode. With an improved fabrication, this efficiency can reach as high as 52%. The device is compact, facilitates on-chip excitation of the SPP, its fabrication is compatible with the standard Si fabrication processes, and, as such it is expected to be very useful in the design of future integrated photonic circuits as well as integrated sensors. Also, this scheme can find applications in studying nonlinear characteristics of materials

On the signs of the imaginary parts of the effective permittivity and permeability in metamaterials

The signs of the imaginary parts of the permittivity and permeability in metamaterials such as split ring resonators and strip wires are investigated. It is shown that the Lorentzian model often used to describe the effective parameters (i.e., the permittivity and permeability) of these metamaterials does not physically allow their imaginary parts to be negative. Moreover, a popular technique used to retrieve the effective parameters of a structure from its S-parameters is also investigated. By comparing the effective parameters for an array of dielectric spheres obtained both from S-parameter simulations and analytical calculations, it is shown that an often observed negative imaginary permittivity obtained from the S-parameters is a result of numerical error in the simulations. This is shown both for the finite element method and finite-difference time-domain simulations

Multibarrier tunneling

We study the tunneling through an arbitrary number of finite rectangular opaque barriers and generalize earlier results by showing that the total tunneling phase time depends neither on the barrier thickness nor on the inter-barrier separation. We also predict two novel peculiar features of the system considered, namely the independence of the transit time (for non resonant tunneling) and the resonant frequency on the number of barriers crossed, which can be directly tested in photonic experiments. A thorough analysis of the role played by inter-barrier multiple reflections and a physical interpretation of the results obtained is reported, showing that multibarrier tunneling is a highly non-local phenomenon.Comment: RevTex, 7 pages, 1 eps figur