Improvement in short-circuited coaxial flange for evaluating microwave superconducting properties at low temperature

5-10In the present study, we have proposed an improvement in terms of the determination of S-parameters of an open flange from its characteristic impedance and propagation constant. With the help of these S-parameters, the actual reflection coefficient of YBCO films deposited on LAO substrate is obtained from the measured reflection coefficient. The surface impedance of three YBCO films is obtained in the range of few ohms in the frequency range from 1 GHz to 40 GHz. The surface resistance of the films reduces at liquid nitrogen temperature, i.e., 77 K, whereas, the surface reactance slightly increases due to kinetic inductance. The conductivity and skin depth are also determined to validate the improvement in the method

A simple method to estimate the loading effects of Al/Si on the characteristic impedance of multilayer microstrip line

The present study aims to experimentally determine the microwave transmission and reflection properties of aluminum thin film grown on silicon using sputtering. A simple microstrip line based structure has been used for the microwave characterization in the frequency range 10 MHz to 26.5 GHz. Complex S-parameter measurements reveal only small differences on silicon loading and aluminum/silicon loading in comparison to the microstrip line. The characteristic impedance (Z) of the microstrip line loaded with silicon and with aluminum/silicon have been obtained corresponding to the length of the loadings using two port microwave analysis. Comparison of loaded microstrip line with no loading shows large changes in the real part well as imaginary part of the characteristic impedance in the frequency range less than 10 GHz. Percentage changes in the real (Z) and imaginary (Z) have been found as ± 40% and ± 10% in average, respectively, for silicon loading in comparison to the no loading case, whereas these changes have been found to be below ±5% for aluminium/silicon loading, thus these smaller changes suggest the similar responses for aluminium/silicon loading and no loading. The results reveal that the propagation can be restored with the application of aluminum with any semiconductor or dielectric as loading on the microstrip line, which shows its potential to be explored for making an individual microwave component

Improvement in short-circuited coaxial flange for evaluating microwave superconducting properties at low temperature

In the present study, we have proposed an improvement in terms of the determination of S-parameters of an open flange from its characteristic impedance and propagation constant. With the help of these S-parameters, the actual reflection coefficient of YBCO films deposited on LAO substrate is obtained from the measured reflection coefficient. The surface impedance of three YBCO films is obtained in the range of few ohms in the frequency range from 1 GHz to 40 GHz. The surface resistance of the films reduces at liquid nitrogen temperature, i.e., 77 K, whereas, the surface reactance slightly increases due to kinetic inductance. The conductivity and skin depth are also determined to validate the improvement in the method

Split-nanotube-based negative index metamaterial for midinfrared wavelengths

A design of split-nanotube-based negative index metamaterial for the infrared spectrum has been proposed. The proposed design and its operation are similar to that of a split-ring resonator (SRR) without inheriting the fabrication difficulties associated with conventional SRR. A negative refractive index has been achieved using a split-nanotube in combination with a periodic array of metallic wires between 1.5 and 3.3    μ m . © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE

Tunable unidirectional scattering of ellipsoidal single nanoparticle

We report unidirectional scattering by tri-axial single ellipsoidal dielectric nanoparticle, which is applicable in the design and development of tunable, low-loss and ultra-compact nanoantennas. Based on the orientation and rotation of the ellipsoidal nanoparticle, three types of modes, one longitudinal mode and two transverse modes, have been excited. Electric and magnetic dipoles have been optically induced in the nanoparticle. Generalized Kerker's conditions have been applied at the interference of optically induced electric and magnetic dipoles. Azimuthally symmetric forward scattering with complete suppression of backward scattering using first Generalized Kerker's condition has been achieved at three different wavelengths for the allowed longitudinal mode and transverse modes in the optical region using single ellipsoidal nanoparticle. Due to 3-fold symmetry, forward scattering can be tuned at different wavelengths, using single ellipsoidal nanoparticle just by changing the direction of the incident electric field

Realization of all optical logic gates using universal NAND gates on photonic crystal platform

In this paper, the design of all-optical logic gates using the combination of universal NAND gates has been proposed. The photonic crystal structure consists of triangular lattice arrangement of air holes in silicon. Initially, the all optical NAND gate has been designed and optimized. Further, the optimized NAND gates have been used and arranged in a combination such that the combined structure behaves as an all-optical logic gate specifically, NOT, AND, OR, XOR and XNOR. The truth table for the designed all-optical logic gates has been verified at an operating wavelength of 1.55 μm. The proposed all optical gates exhibit a response period of 2.168 ps with a bit rate of 0.461 Tb/sec. Further, the contrast ratio for the designed gates has also been obtained

Ultra-narrow band perfect absorber for sensing applications in the visible region

Plasmonics is widely used for converting electromagnetic radiation into energy and confining electromagnetic radiation below the diffraction limit. However, the ultra narrowband and high electromagnetic field cannot be obtained simultaneously because of resistive loss and radiation damping in the metals. In this article, a metallic ultra-narrow band perfect absorber has been proposed consisting of an array of four squares on a silver layer. The structure shows more than 99% absorption and full width at half maxima less than 2 nm at resonance wavelength. The absorption mechanism has been revealed by calculating electric and magnetic field profiles. The dependence of the structure on the geometrical parameters has been studied and the structure has thus been optimized at 692 nm i.e. in the visible range of frequency. The proposed structure is then investigated for sensing application. The structure shows high sensitivity of 680 nm/RIU in the visible range of wavelength and a high figure of merit of 348.72

Rectangular-core large-mode-area photonic crystal fiber for high power applications: design and analysis

A rectangular-core large-mode-area photonic crystal fiber structure has been designed based on the principle of higher order mode filtering by introducing fluorine-doped material rods in the cladding region. The proposed structure has an effective-mode area of fundamental mode (FM) as large as 2147  μm22147  μm2 at 1.064 μm with nominal loss of 1.36×10−2  dB/m1.36×10−2  dB/m and 9.34  dB/m9.34  dB/m at first higher order mode (FHOM), which confirms effective single-mode operation after ∼2.14  m∼2.14  m propagation length. The same structure offers effective-mode area of 5688  μm25688  μm2 a

Zero-index metamaterial based all-dielectric nanoantenna

In this article, a highly directive all-dielectric zero-index metamaterial (ZIM) based nanoantenna has been proposed which has the ability to directionally transmit the radiation from an isotropic quantum emitter. The zero-index metamaterial (ZIM) used here, is basically a rods-in-air type photonic crystal, which exhibits zero-index behaviour owing to the existence of a Dirac-cone at the Gamma (Γ) point in its photonic band structure. The emitter is embedded inside the ZIM and the radiation pattern can be controlled by varying the shape and size of the array

A simple method to estimate the loading effects of Al/Si on the characteristic impedance of multilayer microstrip line

959-964The present study aims to experimentally determine the microwave transmission and reflection properties of aluminum thin film grown on silicon using sputtering. A simple microstrip line based structure has been used for the microwave characterization in the frequency range 10 MHz to 26.5 GHz. Complex S-parameter measurements reveal only small differences on silicon loading and aluminum/silicon loading in comparison to the microstrip line. The characteristic impedance (Z) of the microstrip line loaded with silicon and with aluminum/silicon have been obtained corresponding to the length of the loadings using two port microwave analysis. Comparison of loaded microstrip line with no loading shows large changes in the real part well as imaginary part of the characteristic impedance in the frequency range less than 10 GHz. Percentage changes in the real (Z) and imaginary (Z) have been found as ± 40% and ± 10% in average, respectively, for silicon loading in comparison to the no loading case, whereas these changes have been found to be below ±5% for aluminium/silicon loading, thus these smaller changes suggest the similar responses for aluminium/silicon loading and no loading. The results reveal that the propagation can be restored with the application of aluminum with any semiconductor or dielectric as loading on the microstrip line, which shows its potential to be explored for making an individual microwave component