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Silicon Carbide based electronics remains the most suitable choice to replace silicon in power electronics. Especially in avionics SiC devices represent a reliable solution for reducing weight and size of aircraft power switching technology. However, some issues need to be solved to unleash the full potential of this kind of electronics. The most important challenge is related to the quality of the dielectric/SiC interface and to the techniques implemented to fabricate this interface. In this work, we investigate the morphological and electrical properties of low temperature dielectric films deposited on SiC substrate by using ECR-PECVD. To this end, we fabricated capacitors with silicon dioxide layer, deposited at low temperature, studying their performance with and without surface pretreatments and considering post-annealing effects at different temperatures and times.

In this work we analyze the behavior of pressure sensors based on membranes of chemically very inert materials and robust to atmospheric agents with non-neutral pH. The selected material for cheapness and chemical stability for the manufacture of low-cost pressure sensors is Silicon Carbide, even if a special section is dedicated to diamond membranes pressure sensors because of its unique chemical inertness. Considering also the electromagnetic noise as an aggressive element of the measurement environment, the low-cost reproduction via sensor - optical fiber coupling of a low-finesse Fabry-Perot interferometer was chosen as the reading setup. SiC membranes are realized by nanosecond LASER processing while those in diamond are made by CVD deposition and microelectronic etching techniques.

We investigate optical bistability with light beams propagating in reorientational nematic liquid crystals. In a given interval of input powers, light beams can propagate in either diffracting or soliton states, depending on the “history” of the system. We use biased planar samples exhibiting an abrupt self-focusing response with threshold.

The great interest arisen in the past decades in optical spatial solitons, i.e. self-confined waves supported by the balance between diffraction and nonlinear self-focusing, stems from their character of light-induced waveguides, thus allowing versatile and reconfigurable schemes for optical signal handling and processing [1]. Nematic Liquid Crystals (NLC) are excellent materials for the generation, propagation and the control of spatial solitons, also known as Nematicons [2]: NLC exhibit large birefringence and transparency, coupled with a high reorientational nonlinearity owing to (mean) molecular rotation induced by quasi-static and/or optical frequency electric fields. In addition, the high nonlocal character of their response stabilizes two-dimensional selfconfinement of beams into solitons [3,4]. Hereby we illustrate planar NLC cell configurations whereby nematicons can be electrically routed by propagating in a non-uniform dielectric with transverse and longitudinal variations of the refractive index and/or the orientation of the optic axis, i.e. by undergoing voltage-driven modulation of linear and nonlinear properties. The numerical models and numerical results are in excellent agreement with the experimental data.

Nematicons, i.e., optical spatial solitons in nematic liquid crystals (NLC), have been attracting a great deal of attention due to their unique properties such as, for example, excitability at powers of a few hundred µW and the possibility to be electrically and/or optically (by other light beams) bent.[1] In this work we investigate, both experimentally and theoretically, the nematicon behavior for different degrees of nonlinearity, discussing how the latter affects the beam width (self-focusing) and trajectory (self-steering). Having defined the angle between the molecular director n (i.e., the local optic axis) and the beam wavevector k = n 0 k 0 z (k 0 is the vacuum wavenumber, n 0 the linear refractive index), the propagation of the extraordinary wave in the plane yz in a homogeneous NLC cell of thickness L across x is ruled by the equivalent 2D model [2,3] equation equation where Φ is the beam magnetic field and ψ is the all-optical perturbation on θ, with θ 0 being the unperturbed θ, i.e., θ 0 = Φ (F = 0). In Eqs. (1–2), D y is the diffraction coefficient along y, δ(b) the walk-off of the soliton, γ = [e 0 /(4K)](n ∥ 2 − n ⊥ 2)[Z 0 /(n 0 cosδ)]2, and Δn e 2 is the nonlinear change in the extraordinary refractive index n e . Eq. (2) is a reorientational equation which allows to compute the dielectric properties of the medium (δ and n e ) once it is known the torque exerted by light on the NLC molecules, whereas (1) determines the beam profile once the n-distribution is known. It is clear from Eq. (2) that the nonlinear response, determined by the optical torque, depends on the initial angle θ 0 : hence, by changing θ 0 it is possible to easily modify the nonlinear response of the sample, the latter feasible via an applied bias in a planar cell with interdigitated comb-like electrodes. [3] In the limit ψ θ ≪ 0 , using Eqs. (1–2) it is possible to define two scalar parameters to investigate self-focusing (ruled by Δn e 2) and self-steering (determined by δ) versus θ 0 : a nonlocal Kerr coefficient n 2 , given by n 2 (θ 0 ) = 2γsin[2(θ 0 −δ)]n e 2(θ 0 ) tanδ, and equation, proportional to the sensitivity of δ to the light intensity (Fig. 1), respectively. Numerical simulations of Eqs. (1–2) via BPM confirm the soliton behavior versus θ 0 (Fig. 1). Figure 1 also shows the corresponding experimental results, with an excellent agreement with the theoretical predictions.

Conspicuous efforts have been devoted to exploit spatial solitons for signal processing. In nematic liquid crystals steering of spatial solitons or nematicons has been reported in planar cells. In this Communication, we demonstrate excitation and tunable propagation of spatial solitons in photoconductive Light Valves filled with nematic Liquid Crystals (LCLV). We show that nematicons can be effectively launched and deviated in LCLV, combining self-guidance with parallel nonlinear optical processing.