The article describes the system of intellectual support for remotely operated vehicle (ROV) operators, which provides the precise movements control of the ROV and its depressor-weight along the specified trajectories...
The article describes the system of intellectual support for remotely operated vehicle (ROV) operators, which provides the precise movements control of the ROV and its depressor-weight along the specified trajectories, even in the case when the supporting vessel has no a dynamic positioning system. Proposed system provides operators with visual recommendations and warnings, which are formed in real time on the basis of expert evaluation of the information obtained from various sensors and navigation systems. Software and hardware implementation of the system was carried out for the working class ROV Comanche 18. Experimental studies of the developed system were carried out during an expedition to the Bering Sea on board of the research vessel Akademik M.A. Lavrentyev.
Embedded in silicon β-FeSi2 nanocrystals (NCs) were grown on Si(111) by solid phase epitaxy of a thin iron film followed by Si molecular beam epitaxy. After solid phase epitaxy, a mixture of β-FeSi2 and ε-FeSi nano...
Embedded in silicon β-FeSi2 nanocrystals (NCs) were grown on Si(111) by solid phase epitaxy of a thin iron film followed by Si molecular beam epitaxy. After solid phase epitaxy, a mixture of β-FeSi2 and ε-FeSi nanocrystals is formed on the surface, sometimes β and ε phases coexist inside one nanocrystal. During initial stage of Si molecular beam epitaxy all ε-FeSi transforms into β-FeSi2. β-FeSi2 nanocrystals tend to move following Si growth front. By adjusting growth condition, we manage to prevent the nanocrystals from moving and to fabricate 7-layer n-Si(111)/β-FeSi2_NCs/p+-Si silicon heterostructure with embedded β-FeSi2 NCs. An epitaxial relationship and a stress induced in the nanocrystals by silicon matrix were found to be suitable for indirect to direct band gap transition in β-FeSi2. Of the heterostructure, a n-i-p avalanche photodetector and a light-emitting diode were formed. They have shown relatively good performance: ultrabroadband photoresponse from the visible (400 nm) to short-wavelength infrared (1800 nm) ranges owing to quantum-confined Stark effect in the nanocrystals and optical emission power of up to 25 µW at 9 A/cm2 with an external quantum efficiency of 0.009% at room temperature owing to a direct fundamental transition in stressed β-FeSi2 nanocrystals.
We demonstrate a new tunable MEMS-based WDM&OAM Fabry-Perot filter for simultaneous wavelength (WDM) and Orbital Angular Momentum (OAM) (de)multiplexing. The WDM&OAM filter is suitable for dense on-chip integr...
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ISBN:
(纸本)9781509067374
We demonstrate a new tunable MEMS-based WDM&OAM Fabry-Perot filter for simultaneous wavelength (WDM) and Orbital Angular Momentum (OAM) (de)multiplexing. The WDM&OAM filter is suitable for dense on-chip integration and dedicated for the next generation of optical interconnects utilizing all three degrees of freedom of the electromagnetic waves: wavelength, polarization, and OAM. The WDM&OAM filter consists of two Distributed Bragg Reflectors (DBRs), (see Fig. 1a,b): a bottom one fixed to the substrate and a movable top MEMS DBR. An applied tuning current, changing the resonator length, extends the top DBR and hence selects the central filter wavelength. A spiral phase mask on the top switches the OAM order by ±1, ±2, etc. For a detailed description of the structure and fabrication of the device, please refer to [1,2]. The MEMS filter shows a full-width at half-maximum (FWHM) bandwidth of about 0.2 nm and a free spectral range (FSR) of about 126 nm. The phase mask provides sufficient OAM state purity in a 35 nm window around 1550 nm, covering well the whole C-band.
Vortex beam carrying multiple orbital angular momentum provides a new degree of freedom to manipulate light leading to the various exciting applications as trapping, quantum optics, information multiplexing, etc. Heli...
Vortex beam carrying multiple orbital angular momentum provides a new degree of freedom to manipulate light leading to the various exciting applications as trapping, quantum optics, information multiplexing, etc. Helical wavefront can be generated either via the geometric or the dynamic phase arising from a space-variant birefringence (q-plate) or from phase accumulation through propagation (spiral-phase-plate), respectively. Using fast direct laser writing technique we fabricate and characterize novel hybrid q-plate generating vortex beam simultaneously carrying two different high-order topological charges, which arise from the spin-orbital conversion and the azimuthal height variation of the recorded structures. We approve the versatile concept to generate multiple-OAM vortex beams combining the spin-orbital interaction and the phase accumulation in a single micro-scale device, a hybrid dielectric phase plate.
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