Effect of picosecond strain pulses on thin layers of the ferromagnetic semiconductor (Ga,Mn)(As,P)

The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer of (Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr effect (MOKE). A transient MOKE signal followed by low amplitude oscillations was evidenced, with a strong dependence on applied magnetic field, temperature and ps-ASP amplitude. Careful interferometric measurement of the layer's thickness variation induced by the ps-ASP allowed us to model very accurately the resulting signal, and interpret it as the strain modulated reflectivity (differing for $\sigma_{\pm}$ probe polarizations), independently from dynamic magnetization effects.Comment: 6 pages, 5 figure

The influence of phosphorus content on magnetic anisotropy in ferromagnetic (Ga, Mn) (As, P)/GaAs thin films

International audienceThe magnetic anisotropy of the ferromagnetic semiconductor (Ga, Mn) (As, P) is studied in a material-specific microscopic k . p approach. We calculate the electronic energy band structure of (Ga, Mn) (As, P) quaternary ferromagnetic alloys using a 40-band k . p model and taking into account the s, p-d exchange interaction and the strain of the (Ga, Mn) (As, P) layer on a GaAs substrate. We determine the variations of the carrier effective masses in the strained (Ga, Mn) (As, P)/GaAs system. The magnetic anisotropy constants obtained from our simulations using a mean-field model are compared with the experimental ones determined by ferromagnetic resonance spectroscopy on a set of samples with constant manganese concentration and varying phosphorus concentration. An excellent quantitative agreement between experiment and theory is found for the uniaxial out-of-plane and cubic in-plane anisotropy parameters

Transmission and Reflection Properties of Composite Double Negative Metamaterials in Free Space

Cataloged from PDF version of article.We report free space transmission and the first reflection measurements of a composite double negative (DNG) metamaterial, also known as a left-handed material (LHM). The metamaterial composes of the split-ring-resonators and discontinuous thin wires. Very high transmission values of the metamaterial are observed within a frequency range for which both effective permeability and permittivity are expected to be negative

Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals

We demonstrate negative refraction of microwaves in metallic photonic crystals. The spectral response of the photonic crystal, which manifests both positive and negative refraction, is in complete agreement with band-structure calculations and numerical simulations. The negative refraction observed corresponds to left-handed electromagnetism and arises due to the dispersion characteristics of waves in a periodic medium. This mechanism for negative refraction is different from that in metamaterials.Comment: 13 pages, 4 figure

Investigation of localized coupled-cavity modes in two-dimensional photonic band gap structures

Cataloged from PDF version of article.We present a detailed study of the localized coupled-cavity modes in 2-D dielectric photonic crystals. The transmission, phase, and delay time characteristics of the various coupled-cavity structures are measured and calculated. We observed the eigenmode splitting, waveguiding through the coupled cavities, splitting of electromagnetic waves in waveguide ports, and switching effect in such structures. The corresponding field patterns and the transmission spectra are obtained from the finite-difference-time-domain (FDTD) simulations. We also develop a theory based on the classical wave analog of the tight-binding (TB) approximation in solid state physics. Experimental results are in good agreement with the FDTD simulations and predictions of the TB approximation

Dielectric photonic crystal as medium with negative electric permittivity and magnetic permeability

We show that a two-dimensional photonic crystal (PC) made from a non-magnetic dielectric is a left-handed material in the sense defined by Veselago. Namely, it has negative values of both the electric permittivity $\epsilon$ and the magnetic permeability $\mu$ in some frequency range. This follows from a recently proven general theorem. The negative values of $\epsilon$ and $\mu$ are found by a numerical simulation. Using these values we demonstrate the Veselago lens, a unique optical device predicted by Veselago. An approximate analytical theory is proposed to calculate the values of $\epsilon$ and $\mu$ from the PC band structure. It gives the results that are close to those obtained by the numerical simulation. The theory explains how a non-zero magnetization arises in a non-magnetic PC.Comment: 11 pages 4 figure

Perfect antireflection via negative refraction

We suggest a geometrical framework to discuss the action of slabs of negatively refracting materials. We show that these slabs generate the same orbits as normal materials, but traced out in opposite directions. This property allows us to confirm that the action of any lossless multilayer can be optically cancelled by putting it together with the multilayer constructed as the inverted mirror image, with $\epsilon$ and $\mu$ reversed in sign.Comment: Some typos corrected. New references addes. Accepted for publication in Physics Letters

Reconfigurable quantum metamaterials

By coupling controllable quantum systems into larger structures we introduce the concept of a quantum metamaterial. Conventional meta-materials represent one of the most important frontiers in optical design, with applications in diverse fields ranging from medicine to aerospace. Up until now however, metamaterials have themselves been classical structures and interact only with the classical properties of light. Here we describe a class of dynamic metamaterials, based on the quantum properties of coupled atom-cavity arrays, which are intrinsically lossless, reconfigurable, and operate fundamentally at the quantum level. We show how this new class of metamaterial could be used to create a reconfigurable quantum superlens possessing a negative index gradient for single photon imaging. With the inherent features of quantum superposition and entanglement of metamaterial properties, this new class of dynamic quantum metamaterial, opens a new vista for quantum science and technology.Comment: 16 pages, 8 figure

Enhanced fano resonance of organic material films deposited on arrays of asymmetric split-ring resonators (A-SRRs)

Depositing very thin organic films on the surface of arrays of asymmetric split-ring resonators (A-SRRs) produces a shift in their resonance spectra that can be utilized for sensitive analyte detection. Here we show that when poly-methyl-methacrylate (PMMA) is used as an organic probe (analyte) on top of the A-SRR array, the phase and amplitude of a characteristic molecular Fano resonance associated with a carbonyl bond changes according to the spectral positions of the trapped mode resonance of the A-SRRs and their plasmonic reflection peaks. Furthermore, we localize blocks of PMMA at different locations on the A-SRR array to determine the effectiveness of detection of very small amounts of non-uniformly distributed analyte