Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial

Metamaterials with artificial optical properties have attracted significant research interest. In particular, artificial magnetic resonances in non-unity permeability tensor at optical frequencies in metamaterials have been reported. However, only non-unity diagonal elements of the permeability tensor have been demonstrated to date. A gyromagnetic permeability tensor with non-zero off-diagonal elements has not been observed at the optical frequencies. Here we report the observation of gyromagnetic properties in the near-infrared wavelength range in a magneto-plasmonic metamaterial. The non-zero off-diagonal permeability tensor element causes the transverse magneto-optical Kerr effect (TMOKE) under s-polarized incidence that otherwise vanishes if the permeability tensor is not gyromagnetic. By retrieving the permeability tensor elements from reflection, transmission, and TMOKE spectra, we show that the effective off-diagonal permeability tensor elements reach the 10-3 level at the resonance wavelength (~900 nm) of the split-ring resonators that is at least two orders of magnitude higher than that of magneto-optical materials at the same wavelength. The artificial gyromagnetic permeability is attributed to the change in the local electric field direction modulated by the split-ring resonators. Our study demonstrates the possibility of engineering the permeability and permittivity tensors in metamaterials at arbitrary frequencies, thereby promising a variety of applications of next-generation nonreciprocal photonic devices, magneto-plasmonic sensors, and active metamaterials.

Determination of the Raman polarizability tensor in the optically anisotropic crystal potassium dihydrogen phosphate and its deuterated analog

The Raman tensor of the dominant A1 modes of the nonlinear optical crystalline material potassium dihydrogen phosphate and its 70% deuterated analog have been ascertained. Challenges in determining the A1 mode tensor element values based on previous reports have been resolved using a specially designed experimental setup that makes use of spherical crystal samples. This novel experimental design enabled the determination of measurement artifacts, including polarization rotation of the pump and/or scattered light propagating through the sample and the contribution of additional overlapping phonon modes, which have hindered previous efforts. Results confirmed that the polarization tensor is diagonal, and matrix elements were determined with high accuracy.

On the linear stability of anisotropic pressure equilibria with field-aligned incompressible flow

We derive a sufficient condition for the linear stability of plasma equilibria with incompressible flow parallel to the magnetic field, $\boldsymbol{B}$ , constant mass density and anisotropic pressure such that the quantity $\unicode[STIX]{x1D70E}_{d}=\unicode[STIX]{x1D707}_{0}(P_{\Vert }-P_{\bot })/B^{2}$ , where $P_{\Vert }$ ( $P_{\bot }$ ) is the pressure tensor element parallel (perpendicular) to $\boldsymbol{B}$ , remains constant. This condition is applicable to any steady state without geometrical restriction. The condition, generalising the respective condition for magnetohydrodynamic equilibria with isotropic pressure and constant density derived in Throumoulopoulos & Tasso (Phys. Plasmas, vol. 14, 2007, 122104), involves physically interpretable terms related to the magnetic shear, the flow shear and the variation of total pressure perpendicular to the magnetic surfaces. On the basis of this condition we prove that, if a given equilibrium is linearly stable, then the ones resulting from the application of Bogoyavlenskij symmetry transformations are linearly stable too, provided that a parameter involved in those transformations is positive. In addition, we examine the impact of pressure anisotropy, flow and torsion of a helical magnetic axis, for a specific class of analytic equilibria. In this case, we find that the pressure anisotropy and the flow may have either stabilising or destabilising effects. Also, helical configurations with small torsion and large pitch seem to have more favourable stability properties.

Anisotropic PCL nanofibers embedded with nonlinear nanocrystals as strong generators of polarized second harmonic light and piezoelectric currents

Intense second harmonic generation emission was observed from a single nanofiber, corresponding to an effective 2nd order susceptibility of 80 pm V−1, 4 times greater than the largest 2nd order susceptibility tensor element (21 pm V−1) for a macroscopic 3NA crystal.

Self-Gradient Compensation of Full-Tensor Airborne Gravity Gradiometer

In the process of airborne gravity gradiometry for the full-tensor airborne gravity gradiometer (FTAGG), the attitude of the carrier and the fuel mass will seriously affect the accuracy of gravity gradiometry. A self-gradient is the gravity gradient produced by the surrounding masses, and the surrounding masses include distribution mass for the carrier mass and fuel mass. In this paper, in order to improve the accuracy of airborne gravity gradiometry, a self-gradient compensation model is proposed for FTAGG. The self-gradient compensation model is a fuction of attitude for carrier and time, and it includes parameters ralated to the distribution mass for the carrier. The influence of carrier attitude and fuel mass on the self-gradient are simulated and analyzed. Simulation shows that the self-gradient tensor element Γ x x , Γ x y , Γ x z , Γ y z and Γ z z are greatly affected by the middle part of the carrier, and the self-gradient tensor element Γ y z is affected by the carrier’s fuel mass in three attitudes. Further simulation experiments show that the presented self-gradient compensation method is valid, and the error of the self-gradient compensation is within 0.1 Eu. Furthermore, this method can provide an important reference for improving the accuracy of aviation gravity gradiometry.

Accordion-like collagen fibrils suggested by P-SHG image modeling : implication in liver fibrosis

ABSTRACTSecond-order non-linear optical anisotropy parameter ρ = χ33 / χ31 is calculated for collagen-richt issues considering both a single dominant molecular hyperpolarizability tensor element β333 = β at single helix level and a priori known submicrometric triple helical organization of collagen molecules. Modeling is further improved by taking account of Poisson photonic shot noise of the detection system and simple supra-molecular fibrillar arrangements in order to accurately simulate the dispersion of ρ values in collagen-rich tissues such as tendon, skin and liver vessels. From combined P-SHG experiments and modeling, we next correlate experimental and theoretical statistical distributions of ρ. Our results highlight that the dispersion of experimental ρ values is mainly due to (i) Poisson photonic shot noise in tendon and skin, which proves to have a preponderant effect in P-SHG experiments (ii) variance of supercoil angles of accordion-like fibrils in vessels that is further reduced during the development of liver fibrosis therefore contributing to the rigidity of the tissue. These results open new avenue for future modeling correlating the dispersion of ρ values in P-SHG experiments and the fibrillar architecture as well as the mechanical stiffness of patho-physiological extracellular matrices in collagen tissues.

Femtosecond Material Response Probed by Phase-Stabilized Optical Heterodyne Detected Impulsive Stimulated Raman Scattering

Femtosecond material response of several liquid samples were measured with use of a newly developed “phase-stabilized” optical heterodyne detected impulsive stimulated Raman scattering (ISRS) spectrometer. In this apparatus, the ISRS signal generated with ordinary transient grating geometry is mixed with femtosecond optical pulses (local oscillator, LO) in an interferometer, and the interfered intensity is detected. The subwavelength-accuracy adjustment/stabilization is achieved for the optical path length in the interferometer so that the relative optical phase between the ISRS signal and LO can be controlled. The ISRS signals linearized to each tensor element of the third-order response function were obtained, and discussed.

The piezoelectric tensor element d 33 of KTiOPO4 determined by single crystal X-ray diffraction

The d 33 piezoelectric constant of KTiOPO4 (potassium titanium orthophosphate, KTP) has been determined for two different samples and at temperatures between 100 and 220 K, using high-resolution X-ray diffraction of a single-crystal in an electric field. The observed value of 15 (2) \times 10−12 m V−1 is between the two values of 10.4 and 25.8 \times 10−12 m V−1 found in the literature. The value of d 33 is shown to be constant over the temperature range 100–220 K and no anomaly was observed at the conductor–insulator transition at 150 K. The results obtained are believed to be sample-independent, since the same value was obtained for two different crystals, measured at different sources.