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Endoscopic third ventriculostomy in kids along with long-term interacting hereditary hydrocephalus: the single-center cohort retrospective investigation.
Polarization-encoded free-space quantum communication requires a quantum state source featuring fast modulation, long-term stability, and a low intrinsic error rate. Here we present a polarization encoder that, contrary to previous solutions, generates predetermined polarization states with a fixed reference frame in free-space. The proposed device does not require calibration either at the transmitter or at the receiver and achieves long-term stability. A proof-of-concept experiment is also reported, demonstrating a quantum bit error rate lower than 0.2% for several hours without any active recalibration.The development of integrated vertical III-V nanowire (NW) stimulated emitters in silicon photonics while achieving an efficient light coupling through vertical III-V NW lasers into horizontal optical silicon waveguides is demanding. This is mainly due to the directionality and contradiction of the simultaneously satisfied low threshold stimulated emission conditions of the vertical NWs and efficient light coupling from the NW emitters into the horizontal silicon waveguide. However, we propose a new, to the best of our knowledge, design by taking advantage of resonating features of ring structures and theoretically demonstrate that an interfacial ring resonator between GaAs NW emitters and the silicon waveguide achieves a coupling efficiency up to about 70% at a given wavelength. We also show that the interfacial resonator enables us to adjust the coupling efficiency from about 10% to over 70%. The adjustable coupling efficiency might also be a solution to compromise between the low threshold stimulated emission of NWs and efficient light coupling for realizing efficient silicon couplers based on integrated III-V NW lasers in silicon photonics. Besides the simple fabrication process compared to counterparts, we believe that the novel structure is promising for future optical on-chip data communication in silicon photonics, and the results are expandable to varying wavelengths and materials.Dynamic self-assembly of micropillars has found wide applications in targeted trapping, micro-crystallization and plasmonic sensing. Yet the efficient fabrication of micropillars array with high flexibility still remains a grand challenge. In this Letter, holographic femtosecond laser multi-foci beams (fs-MFBs) based on a spatial light modulator (SLM) is adopted to efficiently create micropillars array with controllable geometry and spatial distribution by predesigning the computer-generated holograms (CGHs). Based on these micropillars array, diverse hierarchical assemblies are formed under the evaporation-induced capillary force. Moreover, taking advantage of the excellent flexibility and controllability of fs-MFBs, on-demand one-bead-to-one-trap of targeted microspheres at arbitrary position is demonstrated with unprecedentedly high capture efficiency, unfolding their potential applications in the fields of microfluidics and biomedical engineering.We demonstrate a reflective wavefront sensor grating suitable for the characterization of high-quality x-ray beamlines and optical systems with high power densities. Operating at glancing incidence angles, the optical element is deeply etched with a two-level pattern of shearing interferometry gratings and Hartmann wavefront sensor grids. Transverse features block unwanted light, enabling binary amplitude in reflection with high pattern contrast. We present surface characterization and soft x-ray reflectometry of a prototype grating array to demonstrate function prior to wavefront measurement applications. A simulation of device performance is shown.Ultra-short optical pulses in the ultraviolet (UV) region are of significant interest for combustion and reacting flow diagnostics, as most important chemical species have electronic resonance transitions in the UV region. Optical parametric amplifiers are typically used for frequency conversion of femtosecond (fs) pulses from near-IR to UV; however, their implementation for practical imaging applications is limited because of the low conversion efficiency and extreme sensitivity to ambient conditions. In this work, we report the implementation of direct-frequency-tripled, fs laser pulses from a tunable amplified laser system for high-resolution imaging of hydroxyl (OH) radical in flames. The fundamental laser output near 850 nm is frequency tripled to obtain approximately 283.3-nm UV radiation. OH planar laser-induced fluorescence (PLIF) imaging at 1 kHz is demonstrated in turbulent flames with image sheet heights in excess of 45 mm and a signal-to-noise ratio better than 25. These results represent over 3× increase in the imaging dimensionality compared to traditional OPA-based systems. Additionally, the third-harmonic generation apparatus is compact, robust, and easy to operate while providing near-Gaussian beam profiles. Simple power scaling suggests another factor of 3 or more increase in sheet height can be achieved for kilohertz-rate practical combustion diagnostics applications.Despite significant merit of depth representation, holographic displays have a considerable limitation speckle. Here, we present speckle reduced holographic displays using an engineered light source with angle diversity for speckle reduction. The level of angle diversity is optimized with consideration of resolution, speckle contrast, and depth of field. To extend the depth of field sacrificed for speckle reduction, we apply tomographic synthesis, exploiting synchronization of a local illumination module and a tunable-focus lens. We implement a benchtop prototype to verify the proposed method, which reduces the speckle contrast averagely by 37.8% while preserving resolution and 4.0 diopter depth of field.We investigate the combination of a nonlinear frequency division multiplexed (NFDM) transmission scheme with midpoint optical phase conjugation (OPC), and show that midpoint OPC introduces power enhancement by compensating for nonlinear impairments. this website It offers a degree of freedom to have a flexible power normalization factor, Pn. Optimizing Pn helps minimize the signal-noise mixing in nonlinear Fourier transform processing for a specific launch power, resulting in improving the system performance significantly. The mid-OPC NFDM system can provide 4.5 dB and 5.6 dB advantages in Q-factor as compared to the conventional NFDM system when the transmission fiber is standard single-mode fiber and a fiber with optimum dispersion, respectively. Mid-OPC NFDM can also offer higher spectral efficiency at a longer transmission reach due to the shorter guard interval.
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