We discuss the tailoring of linear chiroptical effects in three-dimensional plasmonic nanohelices by means of challenging technological nanoscaling approaches, allowing the operation of this ...metamaterial in the optical frequency range. The growth dynamics involved in focused ion and electron beam-induced deposition have been extensively studied and targeted to the realization of complex 3D structures where intrinsic chirality and spatial anisotropy can be controlled at the nanoscale level, toward miniaturized chiral photonics for application in optoelectronics and biological detection.
In this work we propose a new technological approach to fabricate a fully integrated three-axis Hall magnetic sensor. The three axial device fabrication process exploits microfabrication technologies ...applied to a GaAs-based heterostructure to obtain at the same time three mutually orthogonal sensors: an in-plane Hall sensor and two out-of-plane Hall sensors. A two dimensional electron gas (2DEG) AlGaAs/InGaAs/GaAs multilayered structure constitutes the sensing medium of the micromachined devices, whereas an underlying strained InGaAs/GaAs bilayer allows the self-positioning of the out-of-plane devices by virtue of sacrificial layer removal and strain release. The in-plane and out-of-plane Hall sensors, show an excellent linearity versus the magnetic field with an absolute sensitivity as high as 0.03
V/T at 0.6
V bias voltage.
We present in this work the scalar potential formulation of second harmonic generation process in chi((2)) nonlinear analysis. This approach is intrinsically well suited to the applications of the ...concept of circuit analysis and synthesis to nonlinear optical problems, and represents a novel alternative method in the analysis of nonlinear optical waveguide, by providing a good convergent numerical solution. The time domain modeling is applied to nonlinear GaAs asymmetrical waveguide with dielectric discontinuities in the hypothesis of quasi phase matching condition in order to evaluate the efficiency conversion of the second harmonic signal. The accuracy of the modeling is validated by the good agreement with the published experimental results. The effective dielectric constant method allows to extend the analysis also to 3D optical waveguides.
We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. The polarization of the ...noncollinear generated beam is a function of the polarization of both pump beams, thus we experimentally investigated all possible polarization combinations, evidencing that only some of them are allowed and that the nonlinear interaction of optical signals behaves as a polarization based XOR. The experimental results show the peculiarity of the nonlinear optical response associated with noncollinear excitation, and are explained using the expression for the effective second order optical nonlinearity in noncollinear scheme.
In this paper, we analyze the enhancement of ξ (2) nonlinear process in membrane-type circular photonic crystal (PhC) based on GaAs. This unconventional kind of PhC is well suited for the generation ...of whispering gallery modes (WGMs) due to the circular symmetric periodic pattern. By using a laser Gaussian beam at 1.55 μm as pump signal, a WGM at 1.55 μm and a second-harmonic (SH) mode at 0.775 μm are obtained. The SH will be generated in the center of the missing-hole microcavity. The periodic pattern and the microcavity are tailored and optimized providing an SH efficiency conversion as high as 50%. We predict the resonances by an accurate 2-D time-domain model including ξ (2) nonlinearity and by a 3-D finite-element method. Finally, by using a 3-D membrane configuration, we found a total quality factor of the SH mode of the order of 35 000.
A semiconductor laser containing seven InAs-InGaAs stacked quantum-dot (QD) layers was grown by molecular beam epitaxy. Shallow mesa ridge-waveguide lasers with stripe width of 120 mum were ...fabricated and tested. A high modal gain of 41 cm -1 was obtained at room temperature corresponding to a modal gain of ~6 cm -1 per QD layer, which is very promising to enable the realization of 1.3-mum ultrashort cavity devices such as vertical-cavity surface-emitting lasers. Ground state laser action was achieved for a 360-mum-cavity length with as-cleaved facets. The transparency current density per QD layer and internal quantum efficiency were 13 A/cm 2 and 67%, respectively
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