Integrated multi vector vortex beam generator

A novel method to generate and manipulate vector vortex beams in an integrated, ring resonator based geometry is proposed. We show numerically that a ring resonator, with an appropriate grating, addressed by a vertically displaced access waveguide emits a complex optical field. The emitted beam possesses a specific polarization topology, and consequently a transverse intensity profile and orbital angular momentum. We propose a combination of several concentric ring resonators, addressed with different bus guides, to generate arbitrary orbital angular momentum qudit states, which could potentially be used for classical and quantum communications. Finally, we demonstrate numerically that this device works as an orbital angular momentum sorter with an average cross-talk of -10 dB between different orbital angular momentum channels.Comment: 8 pages, 7 figure

Early stage of crystallization of (Zr1-xHfx)62Ni38 metallic glasses

This paper reports a directly observable correlation between the chemical short-range order and the electrical resistivity in metallic glasses. The phase transition corresponding to the first exotherm observed in a differential-scanning-calorimetry (DSC) scan on (Zr1-xHfx)62Ni38 is peculiar in a sense that, contrary to usual metallic glasses, this transition is associated with an increase in electrical resistivity, and x-ray diffraction measurements taken just after the DSC peak shows only the broad diffuse band characteristic of the glassy phase. Electrical resistivity, differential scanning calorimetry, low-temperature superconducting measurements, high-angle x-ray diffraction, transmission electron microscopy, and Mössbauer spectroscopy are used to study this transition in detail

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded \qo{space} for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of OAM $\ell$. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge $q$. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the OAM changes in value by $\ell = \pm2q\hbar$ per photon. We experimentally demonstrate $\ell$ values ranging from $\pm 1$ to $\pm 25$ with conversion efficiencies of $8.6\pm0.4~\%$. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations and nano-scale sensing.Comment: 4 pages, 3 figures - submitted

Electrical resistivity and structural changes upon relaxation and crystallisation of (Mo_(0.6)Ru_(0.4))_(100-x)B_x metallic glasses

Crystallisation of (Mo_(0.6)Ru_(0.4))100_(-x)B_x glasses takes place in three steps: the first step corresponds to the precipitation of the sigma phase Mo_5Ru_3 which decomposes at higher temperatures, the second step is associated with the formation of an HCP solid solution of Mo in Ru, and in the last step the remaining amorphous matrix crystallises in an FCC boride. Detailed electrical resistivity measurements taken below the crystallisation temperature reveal an excess resistivity above the usual linear temperature dependence predicted by the Ziman theory. The increase in resistivity is associated with the onset of long-range compositional inhomogeneity (spinodal decomposition) and the decrease with the onset of crystallisation. The electrical behaviour for samples pre-annealed for 12 hours at various temperatures suggests that boron migration is partly responsible for this excess resistivity. The changes in the radial distribution function of (Mo_(0.6)Ru_(0.4))_(78)B_(22) during annealing at 525 ºC are also reported. The Mott s-d scattering model does not seem to be applicable to these amorphous alloys. The data suggest instead that an important contribution to the conduction comes from the d electrons

Functionalized 3D Architected Materials via Thiol-Michael Addition and Two-Photon Lithography

Fabrication of functionalized 3D architected materials is achieved by a facile method using functionalized acrylates synthesized via thiol-Michael addition, which are then polymerized using two-photon lithography. A wide variety of functional groups can be attached, from Boc-protected amines to fluoroalkanes. Modification of surface wetting properties and conjugation with fluorescent tags are demonstrated to highlight the potential applications of this technique

Barbiturate enhancement of GABA-mediated inhibition and activation of chloride ion conductance: correlation with anticonvulsant and anesthetic actions

The anesthetic-sedative barbiturate pentobarbital (PB) and the anticonvulsant barbiturate phenobarbital (PhB) were applied to mammalian spinal cord neurons in primary dissociated cell culture to assess their effects on: (1) postsynaptic GABA-responses; (2) paroxysmal activity produced by the convulsant bicuculline; (3) resting membrane properties; and (4) spontaneous neuronal activity. The results demonstrated that: (1) anticonvulsant actions occured at barbiturate concentrations which augmented GABA-responses; (2) anesthetic actions occurred at barbiturate concentrations which produced direct increases in chloride conductance; (3) both anticonvulsant and anesthetic actions occurred at clinically relevant concentrations; and (4) concentrations of PhB, but not PB, which produced GABA-augmentation and direct conductance changes were widely separated. These findings support the hypotheses that augmentation of GABA-mediated inhibition and possibly reduction of glutamate (GLU)-mediated excitation form the basis at least in part for barbiturate anticonvulsant action and that addition of direct increases in chloride conductance to augmentation of GABA-mediated inhibition and reduction of GLU-mediated excitation may partially underlie anesthetic-sedative barbiturate action.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24424/1/0000695.pd

Generating optical orbital angular momentum at visible wavelengths using a plasmonic metasurface

The authors acknowledge the support of the Canada Excellence Research Chairs Program.Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin angular momentum that describes their polarisation. Until recently, it was thought that these two ‘rotational’ motions of light were largely independent and could not be coupled during light–matter interactions. However, it is now known that interactions with carefully designed complex media can result in spin-to-orbit coupling, where a change of the spin angular momentum will modify the orbital angular momentum and vice versa. In this work, we propose and demonstrate that the birefringence of plasmonic nanostructures can be wielded to transform circularly polarised light into light carrying orbital angular momentum. A device operating at visible wavelengths is designed from a space-variant array of subwavelength plasmonic nano-antennas. Experiment confirms that circularly polarised light transmitted through the device is imbued with orbital angular momentum of ±2ħ (with conversion efficiency of at least 1%). This technology paves the way towards ultrathin orbital angular momentum generators that could be integrated into applications for spectroscopy, nanoscale sensing and classical or quantum communications using integrated photonic devices.Publisher PDFPeer reviewe

Strong, spectrally-tunable chirality in diffractive metasurfaces

The authors acknowledge the support of the Canada Excellence Research Chairs Program. P.B. acknowledges the support from the Alexander von Humboldt Foundation.Metamaterials and metasurfaces provide a paradigm-changing approach for manipulating light. Their potential has been evinced by recent demonstrations of chiral responses much greater than those of natural materials. Here, we demonstrate theoretically and experimentally that the extrinsic chiral response of a metasurface can be dramatically enhanced by near-field diffraction effects. At the core of this phenomenon are lattice plasmon modes that respond selectively to the illumination’s polarization handedness. The metasurface exhibits sharp features in its circular dichroism spectra, which are tunable over a broad bandwidth by changing the illumination angle over a few degrees. Using this property, we demonstrate an ultra-thin circular-polarization sensitive spectral filter with a linewidth of ~10 nm, which can be dynamically tuned over a spectral range of 200 nm. Chiral diffractive metasurfaces, such as the one proposed here, open exciting possibilities for ultra-thin photonic devices with tunable, spin-controlled functionality.Publisher PDFPeer reviewe

Prospective Associations from Family-of-Origin Interactions to Adult Marital Interactions and Relationship Adjustment

To test the social learning-based hypothesis that marital conflict resolution patterns are learned in the family-of-origin, we used longitudinal, observational data to assess prospective associations between family conflict interaction patterns during adolescence and offspring’s later marital conflict interaction patterns. Forty-seven participants completed an observed family conflict resolution task with their parents at age 14. Seventeen years later, they completed an observed marital conflict interaction task with their spouse, as well as a measure of marital adjustment. As predicted, levels of hostility and positive engagement expressed by parents and adolescents during family interactions were prospectively linked with levels of hostility and positive engagement expressed by offspring and their spouses during marital interactions. Family-of-origin hostility was a particularly robust predictor of marital interaction behaviors; it predicted later marital hostility and engagement controlling for psychopathology and positive family-of-origin engagement. For men, family-of-origin hostility also predicted poorer marital adjustment, an effect that was mediated through hostility in marital interactions. These findings suggest a long-lasting influence of family communication patterns, particularly hostility, on offspring’s intimate communication and relationship functioning

Prospective Associations from Family-of-Origin Interactions to Adult Marital Interactions and Relationship Adjustment

To test the social learning-based hypothesis that marital conflict resolution patterns are learned in the family-of-origin, we used longitudinal, observational data to assess prospective associations between family conflict interaction patterns during adolescence and offspring’s later marital conflict interaction patterns. Forty-seven participants completed an observed family conflict resolution task with their parents at age 14. Seventeen years later, they completed an observed marital conflict interaction task with their spouse, as well as a measure of marital adjustment. As predicted, levels of hostility and positive engagement expressed by parents and adolescents during family interactions were prospectively linked with levels of hostility and positive engagement expressed by offspring and their spouses during marital interactions. Family-of-origin hostility was a particularly robust predictor of marital interaction behaviors; it predicted later marital hostility and engagement controlling for psychopathology and positive family-of-origin engagement. For men, family-of-origin hostility also predicted poorer marital adjustment, an effect that was mediated through hostility in marital interactions. These findings suggest a long-lasting influence of family communication patterns, particularly hostility, on offspring’s intimate communication and relationship functioning