Svanerobb9651

Practical experiments demonstrate the validity of the analysis results and conclusions.Optical switching techniques featuring the fast and large capacity have the potential to enable low latency and high throughput optical data center networks (DCN) to afford the rapid increasing of traffic-boosted applications. Flexibility of the DCN is of key importance to provide adaptive and dynamic bandwidth to handle the variable traffic patterns generated by the heterogeneous applications while optimizing the network resources. Aiming at providing the flexible bandwidth for optical DCNs, we propose and experimentally investigate a software-defined networking (SDN) enabled reconfigurable optical DCN architecture based on novel optical top of rack (OToR) switch exploiting photonic-integrated wavelength selective switch. Experimental results show that the optical bandwidth per link can be automatically reallocated under the management of the deployed SDN control plane according to the variable traffic patterns. With respect to the network with inflexible interconnections, the average packet loss of the reconfigurable DCN decreases 1 order of magnitude and the server-to-server latency performance improves of 42.2%. Scalability investigation illustrates limited (11.7%) performance degradation as the reconfigurable network scale from 2560 to 40960 servers. Both the numerical and experimental assessments validate the proposed DCN with reconfigurable bandwidth feature and lower latency variations with respect to the inflexible DCNs.For achieving high efficiency fiber Bragg gratings (FBGs) utilizing infrared femtosecond laser point-by-point inscription method, it is crucial to make the inscribed periodic structure perfectly in phase. It requires a perfect alignment between the micrometer-sized laser spot with the fiber along the length. Here we report the highly precise fabrication of FBGs by infrared femtosecond laser point-by-point direct-writing method. Image recognition technique is applied to for automatically aligning the trace of the laser spot with the referenced central axis of the fiber along the whole FBG length. FBGs inscription with high spatial precision is confirmed by multiple approaches, including microscopic photographing and FBG spectroscopic measurement. 50 mm-long uniform FBGs with high reflectivity have been successfully demonstrated in a small-core single-mode silica fiber using auto-aligning technique.A concept for an optical holographic security tag is proposed and demonstrated. When illuminated with a laser beam, the image scattered from the tag projects a Quick Response code which encodes identifying information. The image also carries pseudorandom speckle noise, from which a unique speckle pattern "fingerprint" is derived. We show numerically that the tag is unclonable without access to a secret key - the starting conditions of the design algorithm. However, given the key, it is straightforward to reproduce a tag exhibiting the expected fingerprint. Several tags have been realized, implemented as plasmonic meta-holograms, and characterized experimentally. The robustness of the tag to fabrication error and its resilience to counterfeiting are studied in detail and demonstrated experimentally.Rotation modulation technology of inertial navigation system brings navigation performance increasement without any new requirement on inertial sensors. However, device errors still make significant influence on navigation precision. Traditional temperature model identification methods cost plenty of time which reduce production efficiency. Therefore, it is necessary to study an effective solution decreasing temperature resulted errors for engineering application. The paper proposes a fast-self-calibration method for temperature errors. selleckchem A continuous rotation scheme is designed to excite 21 errors inside of 10 minutes. Kalman Filter algorithm is applied to estimate 21 errors taking velocity errors and position errors as measurements. In order to identify temperature model, the rotation scheme is repeated ten times to estimate error parameters under different temperature. Due to the fast rotation scheme, temperature rising rate can be higher than traditional methods and calibration time is shortened. Finally, the method is verified by simulations and experiments.A switchable metasurface composed of plasmonic split ring resonators and a dye-doped liquid crystal is developed. The transmission of the metasurface in the infrared spectral range can be changed by illuminating the dye-doped liquid crystal with light in the visible spectral range. The effect is particularly efficient in the case of hybrid alignment of the liquid crystal, i. e. alignment of the director perpendicular to the surface on one substrate and parallel alignment on the counter substrate. This all-optical switching effect can be attributed to the behavior described in earlier works as colossal optical nonlinearity or surface-induced nonlinear optical effect.The rise in the power conversion efficiency (PCE) of perovskite solar cells has triggered enormous interest in perovskite-based tandem photovoltaics. One key challenge is to achieve high transmission of low energy photons into the bottom cell. Here, nanostructured front electrodes for 4-terminal perovskite/crystalline-silicon (perovskite/c-Si) tandem solar cells are developed by conformal deposition of indium tin oxide (ITO) on self-assembled polystyrene nanopillars. The nanostructured ITO is optimized for reduced reflection and increased transmission with a tradeoff in increased sheet resistance. In the optimum case, the nanostructured ITO electrodes enhance the transmittance by ∼7% (relative) compared to planar references. Perovskite/c-Si tandem devices with nanostructured ITO exhibit enhanced short-circuit current density (2.9 mA/cm2 absolute) and PCE (1.7% absolute) in the bottom c-Si solar cell compared to the reference. The improved light in-coupling is more pronounced for elevated angle of incidence. Energy yield enhancement up to ∼10% (relative) is achieved for perovskite/c-Si tandem architecture with the nanostructured ITO electrodes. It is also shown that these nanostructured ITO electrodes are also compatible with various other perovskite-based tandem architectures and bear the potential to improve the PCE up to 27.0%.