Simmonshougaard3951

The proposed low-complexity sparse AT-NLE shows great potential for high-performance and low-cost IM/DD optical transmission systems.Uniaxial anisotropy in nonlinear birefringent crystals limits the efficiency of nonlinear optical interactions and breaks the spatial symmetry of light generated in the parametric down-conversion (PDC) process. Therefore, this effect is usually undesirable and must be compensated for. However, high gain may be used to overcome the destructive role of anisotropy in order to generate bright two-mode correlated twin-beams. In this work, we provide a rigorous theoretical description of the spatial properties of bright squeezed light in the presence of strong anisotropy. We investigate a single crystal and a system of two crystals with an air gap (corresponding to a nonlinear SU(1,1) interferometer) and demonstrate the generation of bright correlated twin-beams in such configurations at high gain due to anisotropy. We explore the mode structure of the generated light and show how anisotropy, together with crystal spacing, can be used for radiation shaping.Dual Comb Spectroscopy proved its versatile capabilities in molecular fingerprinting in different spectral regions, but not yet in the ultraviolet (UV). EGFR inhibitors list Unlocking this spectral window would expand fingerprinting to the electronic energy structure of matter. This will access the prime triggers of photochemical reactions with unprecedented spectral resolution. In this research article, we discuss the milestones marking the way to the first UV dual comb spectrometer. We present experimental and simulated studies towards UV dual comb spectroscopy, directly applied to planned absorption measurements of formaldehyde (centered at 343 nm, 3.6 eV) and argon (80 nm, 16 eV). This will enable an unparalleled relative resolution of up to 10-9 - with a table-top UV source surpassing any synchrotron-linked spectrometer by at least two and any grating-based UV spectrometer by up to six orders of magnitude.The two-beam GaoFen-7 (GF-7) laser altimeter is China's first formal spaceborne laser altimeter system for Earth observations. In this article, a calibration method based on simulation waveform matching is proposed to correct the laser pointing error now that the satellite is in orbit. In the method, the optimal position of the laser footprint is searched using simulated and actual waveforms. Then, the laser pointing is calibrated based on the laser footprint optimal position. In this paper, after calibration of the GF-7 laser pointing, infrared detectors are used to capture laser footprints for accuracy verification. The results show that the GF-7 laser pointing accuracy is greatly improved by the method; the laser pointing accuracy of beam 1 is approximately 5.4 arcsec, and that of beam 2 is approximately 5.7 arcsec. Subsequently, two laser footprints are selected for GF-7 laser calibration in the Helan Mountains, China, and AW3D30 digital surface model (DSM) and GPS/RTK data are used to verify the laser elevation measurement accuracy (EMA). The results show that the EMA of the GF-7 laser is significantly improved after calibration. Over flat terrain, the EMA of the GF-7 laser is improved by 10 times, from 3.74 ± 0.55 m to 0.35 ± 0.50 m, verifying the effectiveness of the proposed method.In this paper, we propose a roll-to-plate (R2P) projection micro-stereolithography (PSL) 3D printer, where layers of photopolymer are transferred and photopolymerized through a flexible membrane. Benefitting from the "coat-expose-peel" procedure, highly viscous material can be printed quickly with good vertical resolution. Most importantly, the multinozzle dispensing method enables the fabrication of multimaterial architectures with high throughput, low material consumption, and low cross-contamination. R2P-PSL exhibits superior features for flexible 3D printing in terms of material complexity. For this purpose, we envision infinite scenarios involving potential applications in bionics, biotechnology, microcircuit graphics, photonic devices, microfluidics and material science.When the quasi-phase matching (QPM) parameters of the χ(2) nonlinear crystal rotate along a closed path, geometric phase will be generated in the signal and idler waves that participate in the nonlinear frequency conversion. In this paper, we study two rotation schemes, full-wedge rotation and half-wedge rotation, of the QPM parameters in the process of fully nonlinear three-wave mixing. These two schemes can effectively suppress the uncertainty in creating the geometric phase in the nonlinear frequency conversion process when the intensity of the pump is depleted. The finding of this paper provides an avenue toward constant control of the geometric phase in nonlinear optics applications and quantum information processing.We realize and numerically demonstrate the analogue of electromagnetically induced transparency (EIT) with a high-Q factor in a metal-dielectric bilayer terahertz metamaterial (MM) via bright-bright mode coupling and bright-dark mode coupling. The dielectric MM with silicon dimer rectangular-ring-resonator (Si-DRR) supports either a bright high-Q toroidal dipole resonance (TD) or a dark TD with infinite Q value, while plasmonic MM with metallic rectangular-ring-resonator (M-RR) supports a low-Q electric dipole resonance (ED). The results show that the near-field coupling between the dark TD and bright ED behaves just as that between the two bright modes, which is dependent on the Q factor of the TD resonance. Further, due to the greatly enhanced near-field coupling between the bright ED and dark TD, the coupling distance is significantly extended to about 1.9 times of the wavelength (in media), and robust EIT with large peak value over 0.9 and high Q-factor is achieved. The proposed bilayer MM provides a new EIT platform for design and applications in high-Q cavities, sensing, and slow-light based devices.The distinct optical properties of solid and liquid silicon nanoparticles are exploited to determine the distribution of gas-borne solid and liquid particles in situ using line-of-sight attenuation measurements carried out across a microwave plasma reactor operated at 100 mbar. The ratio between liquid and solid particles detected downstream of the plasma varied with measurement location, microwave power, and flow rate. Temperatures of the liquid particles were pyrometrically-inferred using a spectroscopic model based on Drude theory. The phase-sensitive measurement supports the understanding of nanoparticle formation and interaction and thus the overall gas-phase synthesis process.Owing to great luminescent monochromaticity, high stability, and independent of automatic color filter, low dimensional ultraviolet light-emitting diodes (LEDs) via the hyperpure narrow band have attracted considerable interest for fabricating miniatured display equipments, solid state lighting sources, and other ultraviolet photoelectrical devices. In this study, a near-ultraviolet LED composed of one Ga-doped ZnO microwire (ZnOGa MW) and p-GaN layer was fabricated. The diode can exhibit bright electroluminescence (EL) peaking at 400.0 nm, with a line width of approximately 35 nm. Interestingly, by introducing platinum nanoparticles (PtNPs), we achieved an ultraviolet plasmonic response; an improved EL, including significantly enhanced light output; an observed blueshift of main EL peaks of 377.0 nm; and a reduction of line width narrowing to 10 nm. Working as a powerful scalpel, the decoration of PtNPs can be employed to tailor the spectral line profiles of the ultraviolet EL performances. Also, a rational physical model was built up, which could help us study the carrier transportation, recombination of electrons and holes, and dynamic procedure of luminescence. This method offers a simple and feasible way, without complicated fabricating technology such as an added insulating layer or core shell structure, to realize hyperpure ultraviolet LED. Therefore, the proposed engineering of energy band alignment by introducing PtNPs can be employed to build up high performance, high spectral purity luminescent devices in the short wavelengths.Visible light communication (VLC) system has emerged as a promising solution for high-speed underwater data transmission. To tackle with the linear and nonlinear impairments, deep learning inspired equalization is introduced into VLC. Despite their success in accuracy, deep learning approaches often come with high computational budget. In this paper, we propose an adaptive deep-learning equalizer based on complex-valued neural network and constellation partitioning scheme for 64 QAM-CAP modulated underwater VLC (UVLC) system. Inspired by the fact that symbols modulated at different levels experience various extent of nonlinear distortion, we adaptively partition the received symbols in constellation and design compact equalization networks for specific regions to reduce computation consumption. Experiments demonstrate that the partitioned equalizer can achieve the bit error rate below the 7% hard-decision forward error correction (HD-FEC) limit of 3.8 × 10-3 at 2.85 Gbps similar to the standard complex-valued network, yet with 56.1% total computational complexity reduction. This work paves the path for online data processing in high speed UVLC system.Efficient white upconversion (UC) luminescence is obtained in Yb3+/Eu3+ doubly-doped optical glass ceramic (GC) for the first time. KYb3F10 nanocrystals are controllably precipitated from the amorphous networks via the inducing of Yb3+. Yb3+ ions are spontaneously confined within the compact fluoride crystal structures to produce efficient blue UC emissions of Yb3+-Yb3+ pairs. Eu3+ ions are easily incorporated into the KYb3F10 crystal lattices. Owing to the extremely short interionic distance in the crystal structures, intense green UC emissions apart from the red emissions of Eu3+ are observed, which are not obtained by the traditional Yb3+/Eu3+ doubly-doped GCs. As a result, white UC emissions are synthesized based on the three-primary-color principle and the emission intensities of GCs are dramatically enhanced as compared to glass. The designed GCs provide novel optical gain materials for the promising applications in three-dimensional display, solid-state lighting and tunable fiber lasers.Controllable conversion between propagating light waves and surface waves (SWs) has recently attracted significant research interests. This paper demonstrates, via numerical simulation, for the first time all-dielectric SW converters that possess a tunable and directional SW conversion efficiency. The SW converters contain multiple metagratings of Si pillars embedded in a deformable substrate. In the analysis, an infinitely large, bi-periodic metagrating under the illumination of linearly polarized light is considered first. The SW conversion efficiency of this metagrating can be modulated between 4.3% and 51.0% for incident light frequency at 0.8 THz by stretching the deformable substrate along the direction of SW propagation. Subsequently, two SW converters under circularly polarized light illumination are analyzed, where a similar level of efficiency modulation is retained in finite-sized metagratings. In these converters, only the metagrating channels along the stretch direction have a strong SW conversion efficiency, which can reach 40.