One of the main challenges of next generation optical communication is to increase the available bandwidth while reducing the size, cost and power consumption of photonic integrated circuits. Graphene has been recently proposed to be integrated with silicon photonics to meet these goals because of its high mobility, fast carrier dynamics and ultra-broadband optical properties. We focus on graphene photodetectors for high speed datacom and telecom applications based on the photo-thermo-electric effect, allowing for direct optical power to voltage conversion, zero dark current, and ultra-fast operation. We report on a chemical vapour deposition graphene photodetector based on the photo-thermoelectric effect, integrated on a silicon waveguide, providing frequency response >65 GHz and optimized to be interfaced to a 50 Ω voltage amplifier for direct voltage amplification. We demonstrate a system test leading to direct detection of 105 Gbit s−1 non-return to zero and 120 Gbit s−1 4-level pulse amplitude modulation optical signals.

We demonstrate experimentally manipulation of supercurrent in Al-AlOx-Ti Josephson tunnel junctions by injecting quasiparticles in a Ti island from two additional tunnel-coupled Al superconducting reservoirs. Both supercurrent enhancement and quenching with respect to equilibrium are achieved. We demonstrate cooling of the Ti line by quasiparticle injection from the normal state deep into the superconducting phase. A model based on heat transport and non-monotonic current-voltage characteristic of a Josephson junction satisfactorily accounts for our findings.

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The benefits of cryogenic cooling by liquid nitrogen in cutting of titanium alloys have often been evaluated as a comparison\ud to dry machining conditions. However, it is more interesting to quantitatively assess the performance of cryogenic\ud conditioning of the process with respect to standard industrial conditions, that is, with respect to flood emulsion cooling.\ud The technical and scientific literature is scarce and somehow contradictory, especially in terms of cutting forces and\ud coefficient of friction. The aim of this article is to enrich the common base of experimental data, by conducting a comparison\ud of traditional and cryogenic turning of Ti6Al4V in a region of cutting parameters particularly relevant to the\ud aerospace industry, where no previous data are available. This study confirms that cryogenic machining is able to\ud increase the tool life, even with respect to wet cutting. Besides, the results show that not only cutting forces are reduced\ud but also a small, albeit significant, reduction can be achieved in the coefficient of friction at the tool–workpiece interface

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We report on the low-temperature growth of heavily Si-doped (>1020 cm−3) n+-type GaN by N-rich ammonia molecular beam epitaxy (MBE) with very low bulk resistivity (<4 × 10−4 Ω·cm). This is applied to the realization of regrown ohmic contacts on InAlN/GaN high electron mobility transistors. A low n+-GaN/2 dimensional electron gas contact resistivity of 0.11 Ω·mm is measured, provided an optimized surface preparation procedure, which is shown to be critical. This proves the great potentials of ammonia MBE for the realization of high performance electronic devices.

Ti-6Al-4 V titanium alloy is a popular material in industrial applications (e.g. aerospace, oil & gas, medical) due to its superior mechanical properties, although its low thermal conductivity and high chemical reactivity with other materials make it a hard-to-cut material. A finite element model (FEM) was developed in the present investigation to simulate dry and cryogenic orthogonal cutting of Ti-6Al-4 V by using TiAlN coated carbide inserts. Numerical prediction of the effect of the superior cryogenic cooling on chip formation, cutting and thrust forces were investigated. The simulations were validated by the comparison with experimental results. The model calibration was performed with experimental data on dry cutting and then the model was used for predicting the cryogenic cooling case. The validated FEM models were used to compare the chip formation in dry cutting and cryogenic cutting in order to point out some differences in terms of chip segmentation frequency and chip thickness and gain additional knowledge