Design of narrowband infrared emitters by hybridizing guided-mode resonance structures with van der Waals materials

In this paper, narrowband emitters have been designed using particle swarm optimization (PSO) in the 10-20 {\mu}m infrared range. The device structure consists of an anisotropic {\alpha}-MoO3 layer combined with the one- and two-dimensional guided-mode resonance structures. Well-defined absorption lines are present in the reflection spectrum for both TE and TM polarizations, thereby yielding narrowband emissivity at desired wavelengths. The band structure of the designed emitters under TM polarization demonstrates distinct features unlike its TE counterpart. These features are attributed to the interaction between guided-mode resonances and phonon polaritons. The results are relevant for applications in active and passive photonic elements in mid- and long-wave IR bands

The feasibility of correlation between superconductivity and magnetic monopole: Establishment of semi-classical electrodynamics projection, TKH topological theory and dynamic vortex models

In this paper, a feasibility of semi-classical electromagnetic description together with experimental data, T-K-H topological and dynamic models and theory of vortex considered to justify the relation between superconductivity phenomena and magnetic monopole. We find that the electromagnetic energy of magnetic monopole is in agreement with vortex energy in topological theory and it can get close to thermal energy at room temperature. Indeed, these models suggest that the origin of the hot superconductivity may be magnetic monopoles with QM-Cl = 137 e (magnetic charge in classical approach) or QM-Q =137/2 e (magnetic charge in quantum approach), and the electrical conductivity is related to the mobile monopole or vortices. This research shows that the electrical permittivity ({\epsilon}) and magnetic permeability ({\mu}) of matter have a key role in the superconductive properties. We propose that this model may justify the hot superconductivity properties.Comment: 24 pages, 5 figure

High performance Bragg gratings in chalcogenide glass rib waveguides written with a modified Sagnac interferometer: fabrication and characterization

We report high performance Bragg gratings in As₂S₃ chalcogenide glass rib waveguides, written with a modified Sagnac interferometer for the first time. Grating growth dynamics obtained from an in-situ monitoring system are presented and analyzedM. Shokooh-Saremi, V. G. Ta’eed, N. J. Baker, I. C. M. Littler, D. J. Moss, B. J. Eggleton, Y. Ruan and B. Luther-Davie

Self-phase modulation-based integrated optical regeneration in chalcogenide waveguides

Copyright © 2006 IEEEWe demonstrate integrated all-optical 2R regenerators based on Kerr optical nonlinearities (subpicosecond response) in chalcogenide glass waveguides with integrated Bragg grating filters. By combining a low loss As₂S₃ rib waveguide with an in-waveguide photo-written Bragg grating filter, we realize an integrated all-optical 2R signal regenerator with the potential to process bit rates in excess of 1 Tb/s. The device operates using a combination of self phase modulation induced spectral broadening followed by a linear filter offset from the input centerwavelength.A nonlinear power transfer curve is demonstrated using 1.4 ps pulses, sufficient for suppressing noise in an amplified transmission link. We investigate the role of dispersion on the device transfer characteristics, and discuss future avenues to realizing a device capable of operation at subwatt peak power levels.Vahid G. Ta’eed, Mehrdad Shokooh-Saremi, Libin Fu, Ian C. M. Littler, David J. Moss, Martin Rochette, Benjamin J. Eggleton, Yinlan Ruan, and Barry Luther-Davie

Slow-light switching in nonlinear Bragg-grating coupler

We study propagation and switching of slow-light pulses in nonlinear couplers with phase-shifted Bragg gratings. We demonstrate that power-controlled nonlinear self-action of light can be used to compensate dispersion-induced broadening of pulses through the formation of gap solitons, to control pulse switching in the coupler, and to tune the propagation velocity.Comment: 3 pages, 4 figure

Optimized Si/SiO2 high contrast grating mirror design for mid-infrared wavelength range: robustness enhancement

A high reflectivity and polarization selective high contrast grating mirror has been designed with the use of an automated optimization algorithm. Through a precise study of the tolerance of the different lengths of the structure, the robustness with respect to the fabrication errors has been enhanced to high tolerance values between 5 % and 210 %. This adjustment of the dimensions of the structure leads to a 250 nm large bandwidth mirror well adapted for a VCSEL application at \lambda = 2.65 $\mu$m and can easily be scaled for other wavelengths.Comment: The final publication is available at http://www.sciencedirect.com/science/article/pii/S0030399211002672\#FCANot

Deep-subwavelength Phase Retarders at Mid-Infrared Frequencies with van der Waals Flakes

Phase retardation is a cornerstone of modern optics, yet, at mid-infrared (mid-IR) frequencies, it remains a major challenge due to the scarcity of simultaneously transparent and birefringent crystals. Most materials resonantly absorb due to lattice vibrations occurring at mid-IR frequencies, and natural birefringence is weak, calling for hundreds of microns to millimeters-thick phase retarders for sufficient polarization rotation. We demonstrate mid-IR phase retardation with flakes of $\alpha$-molybdenum trioxide ($\alpha$-MoO$_3$) that are more than ten times thinner than the operational wavelength, achieving 90 degrees polarization rotation within one micrometer of material. We report conversion ratios above 50% in reflection and transmission mode, and wavelength tunability by several micrometers. Our results showcase that exfoliated flakes of low-dimensional crystals can serve as a platform for mid-IR miniaturized integrated polarization control.Comment: 8 pages, 5 figure

Retrieving optical parameters of emerging van der Waals flakes

High-quality low-dimensional layered and van der Waals materials are typically exfoliated, with sample cross sectional areas on the order of tens to hundreds of microns. The small size of flakes makes the experimental characterization of their dielectric properties unsuitable with conventional spectroscopic ellipsometry, due to beam-sample size mismatch and non-uniformities of the crystal axes. Previously, the experimental measurement of the dielectrirc permittivity of such microcrystals was carried out with near-field tip-based scanning probes. These measurements are sensitive to external conditions like vibrations and temperature, and require non-deterministic numerical fitting to some a priori known model. We present an alternative method to extract the in-plane dielectric permittivity of van der Waals microcrystals, based on identifying reflectance minima in spectroscopic measurements. Our method does not require complex fitting algorithms nor near field tip-based measurements and accommodates for small-area samples. We demonstrate the robustness of our method using hexagonal boron nitride and {\alpha}-MoO3, and recover their dielectric permittivities that are close to literature values.Comment: 10 pages, 4 figure and 3 table

The role of nanoliposome bilayer composition containing soluble leishmania antigen on maturation and activation of dendritic cells

Objective(s): Dendritic cells (DCs) play a critical role in activation of T cell responses. Induction of type1 T helper (Th1) immune response is essential to generate protective immunity against cutaneous leishmaniasis. The intrinsic tendency of liposomes to have interaction with antigen-presenting cells is the main rationale to utilize liposomes as antigen carriers. In the present study, the effect of lipid phase transition temperature on DCs maturation and liposome uptake by murine bone marrow derived dendritic cells and human monocyte derived dendritic cells was investigated.Materials and Methods: Two cationic liposomal formulations consisting of DOTAP and DSPC/DOTAP were prepared and contained soluble leishmania antigen. Liposomes were incubated with immature or mature DCs derived from bone marrow (BMDCs) of C57BL/6 (which are resistant to cutaneous leishmaniasis), BALB/c mice (susceptible to cutaneous leishmaniasis) or DCs derived from human monocytes (MoDCs). The expression of DCs co-stimulatory markers and liposomal uptake were evaluated by flow cytometry method. Results: DCs which were encountered to liposomes consisting of DSPC showed significantly more expression of co-stimulatory molecules in cells from both human and C57BL/6 mice but not in cells from BALB/c mice. Conclusion: It is concluded that cationic liposomes consisting of DSPC are an effective adjuvant for antigen delivery in case of MoDCs and BMDCs from C57BL/6 mice. Moreover, DCs from different origins act differently in uptake of liposomes