Environment-Dependent Eu-Activated BaCaK(PO) toward White-Light Emission by Chemical Cosubstitution of the (BO) Anion Group.

Investigating the phosphors doped with single activators in a single component to realize white-light emission is urgently desired for phosphor-converted white-light-emitting diodes. In this work, on the basis of the chemical unit cosubstitution strategy, the new borophosphate phosphors BaCaK(PO)(BO):0.02Eu with a mixed anion group were prepared.

Digital screen time and its effect on preschoolers' behavior in China: results from a cross-sectional study.

Background: The aims of the study were to determine the effects of electronic exposure on behaviors of preschoolers, which could provide scientific grounds to the control of digital screen time and usage of electronics.

Methods: Children of 3-6 years of age (n = 1897) and their families were included in this study. The daily screen time were recorded for seven days.

Switchable detector array scheme to reduce the effect of single-photon detector's deadtime in a multi-bit/photon quantum link.

We explore the use of a switchable single-photon detector (SPD) array scheme to reduce the effect of a detector's deadtime for a multi-bit/photon quantum link. The case of data encoding using M possible orbital-angular-momentum (OAM) states is specifically studied in this paper. Our method uses SPDs with a controllable × optical switch and we use a Monte Carlo-based method to simulate the quantum detection process.

Single-End Adaptive Optics Compensation for Emulated Turbulence in a Bi-Directional 10-Mbit/s per Channel Free-Space Quantum Communication Link Using Orbital-Angular-Momentum Encoding.

A single-end adaptive-optics (AO) module is experimentally demonstrated to mitigate the emulated atmospheric turbulence effects in a bi-directional quantum communication link, which employs orbital angular momentum (OAM) for data encoding. A classical Gaussian beam is used as a probe to detect the turbulence-induced wavefront distortion in the forward direction of the link. Based on the detected wavefront distortion, an AO system located on one end of the link is used to simultaneously compensate for the forward and backward channels.

Orthogonally polarized frequency comb generation from a Kerr comb via cross-phase modulation.

We experimentally demonstrate that a single microresonator can emit two orthogonally polarized individually coherent combs: (i) a strong polarized soliton comb and (ii) an orthogonally polarized continuous wave seeded weaker comb, generated from the first one via cross-phase modulation, sharing the repetition rate of the soliton comb. Experimental results show that the power of the transverse electric-polarized seed can be well below the threshold of comb generation (e.g.

Coherent optical wireless communication link employing orbital angular momentum multiplexing in a ballistic and diffusive scattering medium.

We experimentally investigate the scattering effect on an 80 Gbit/s orbital angular momentum (OAM) multiplexed optical wireless communication link. The power loss, mode purity, cross talk, and bit error rate performance are measured and analyzed for different OAM modes under scattering levels from ballistic to diffusive regions. Results show that (i) power loss is the main impairment in the ballistic scattering, while the mode purities of different OAM modes are not significantly affected; (ii) in the diffusive scattering, however, the performance of an OAM-multiplexed link further suffers from the increased cross talk between the different OAM modes.

Demonstration of a 10 Mbit/s quantum communication link by encoding data on two Laguerre-Gaussian modes with different radial indices.

We experimentally demonstrate a 10 Mbit/s free-space quantum communication link using data encoding on orthogonal Laguerre-Gaussian (LG) modes with the same azimuthal index but different radial indices. Data encoding on two LG modes (i.e.

Experimental utilization of repeated spatial-mode shifting for achieving discrete delays in a free-space recirculating loop.

We demonstrate an optical recirculating delay loop by shifting the spatial mode order of orbital-angular-momentum (OAM) beams in the free-space. The desired delay can be selected at the loop output by exploiting the orthogonality of the OAM modes. When sending a 20-Gbaud quadrature-phase-shift-keyed (QPSK) signal through the delay system, three recirculations are demonstrated, each with an additional delay of 2.

400-Gbit/s QPSK free-space optical communicationlink based on four-fold multiplexing of Hermite-Gaussian or Laguerre-Gaussian modes by varying both modal indices.

We experimentally demonstrate the four-fold multiplexing of Hermite-Gaussian (HG) or Laguerre-Gaussian (LG) modes to achieve a 400 Gbit/s quadrature-phase-shift-keyed (QPSK) free-space optical communication link. In this experiment, both modal indices for the HG and LG modes are simultaneously utilized to achieve a larger potential orthogonal modal space. Moreover, we also investigate and compare the effects of aperture size, lateral displacement, and rotation on the system.

Structural and functional characterization of hMEX-3C Ring finger domain as an E3 ubiquitin ligase.

MEX-3C, a novel RNA binding E3 ubiquitin ligases, contains two N-terminal heterogeneous nuclear ribonucleoprotein K homology (KH) domains and C-terminal Ring finger domain. Recent evidence has suggested that human MEX-3C has a strong bondage with carcinogenesis and the MEX-3C-mediated ubiquitination of RIG-I is essential for the antiviral innate immune response. Moreover, the Ring finger domain of MEX-3C could regulate the degradation of HLA-A2 (an MHC-I allotype) mRNA with a novel mechanism.

Experimental demonstration of beaconless beam displacement tracking for an orbital angular momentum multiplexed free-space optical link.

In this Letter, we experimentally demonstrate beaconless beam displacement tracking for free-space optical communication link multiplexing multiple orbital angular momentum (OAM) beams, where the data-carrying OAM beams are used for position detection. 400 Gbit/s data transmission is demonstrated under emulated lateral displacement of up to ±10  mm with power penalties of less than 3 dB for all channels. Channel crosstalk is reduced by the beam tracking system to below -18  dB.

High-Capacity Free-Space Optical Communications Between a Ground Transmitter and a Ground Receiver via a UAV Using Multiplexing of Multiple Orbital-Angular-Momentum Beams.

We explore the use of orbital-angular-momentum (OAM)-multiplexing to increase the capacity of free-space data transmission to moving platforms, with an added potential benefit of decreasing the probability of data intercept. Specifically, we experimentally demonstrate and characterize the performance of an OAM-multiplexed, free-space optical (FSO) communications link between a ground transmitter and a ground receiver via a moving unmanned-aerial-vehicle (UAV). We achieve a total capacity of 80 Gbit/s up to 100-m-roundtrip link by multiplexing 2 OAM beams, each carrying a 40-Gbit/s quadrature-phase-shift-keying (QPSK) signal.

Spatially multiplexed orbital-angular-momentum-encoded single photon and classical channels in a free-space optical communication link.

We experimentally demonstrate spatial multiplexing of an orbital angular momentum (OAM)-encoded quantum channel and a classical Gaussian beam with a different wavelength and orthogonal polarization. Data rates as large as 100 MHz are achieved by encoding on two different OAM states by employing a combination of independently modulated laser diodes and helical phase holograms. The influence of OAM mode spacing, encoding bandwidth, and interference from the co-propagating Gaussian beam on registered photon count rates and quantum bit error rates is investigated.

Using a complex optical orbital-angular-momentum spectrum to measure object parameters.

Light beams can be characterized by their complex spatial profiles in both intensity and phase. Analogous to time signals, which can be decomposed into multiple orthogonal frequency functions, a light beam can also be decomposed into a set of spatial modes that are taken from an orthogonal basis. Such decomposition can potentially provide a tool for spatial spectrum analysis, which may enable stable, accurate, and robust extraction of physical object information that may not be readily achievable using traditional approaches.

Orbital angular momentum beams generated by passive dielectric phase masks and their performance in a communication link.

We demonstrate the generation of orbital angular momentum (OAM) beams using high-efficient polarization-insensitive phase masks. The OAM beams generated by the phase masks are characterized in terms of their tolerance to misalignment (lateral displacement or tilt) between the incident beam and phase mask. For certain scenarios, our results show that (a) when the tilt angle is within the range of -20 to +20  deg, the crosstalk among modes is less than -15  dB; and (b) lateral displacement of 0.

Spatial light structuring using a combination of multiple orthogonal orbital angular momentum beams with complex coefficients.

Analogous to time signals that can be composed of multiple frequency functions, we use uniquely structured orthogonal spatial modes to create different beam shapes. We tailor the spatial structure by judiciously choosing a weighted combination of multiple modal states within an orthogonal orbital angular momentum (OAM) basis set, creating desired beam intensity "shapes." The weights of the OAM beams to be combined forms a Fourier pair with the spatial intensity distribution in the azimuthal direction of the resultant beam.

Dual-pump generation of high-coherence primary Kerr combs with multiple sub-lines.

We experimentally generate high-coherence primary Kerr combs with multiple sub-lines by using dual pumps and demonstrate the application of a primary comb state in multichannel communications. We find that more than 10 primary comb lines can be generated within the spectrum of modulation instability gain in our microring resonator. The generation is also verified by numerical simulations and the measured linewidth confirms the high coherence of the generated primary comb lines.

Localization from the unique intensity gradient of an orbital-angular-momentum beam.

We propose and simulate the use of the unique intensity gradient of beams carrying orbital angular momentum (OAM) for tracking and localization of an object. We design a three-pixel detector structure to efficiently determine the intensity gradient of an OAM beam. The resultant intensity gradient is then used to calculate the offset direction and distance of the target object from the center of the OAM beam.

Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing.

There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed.

Demonstration of Tunable Steering and Multiplexing of Two 28 GHz Data Carrying Orbital Angular Momentum Beams Using Antenna Array.

In line-of-sight communication systems, accurate alignment between the transmitter and receiver is important to guarantee sufficient signal power at the receiver. Such alignment is even more important for orbital angular momentum (OAM) multiplexing systems since misalignment between the transmitter and receiver may cause crosstalk among channels. In this paper, we demonstrate the simultaneous generation and tunable steering of two OAM beams utilising a custom-designed circular antenna array at 28 GHz.

Multipath Effects in Millimetre-Wave Wireless Communication using Orbital Angular Momentum Multiplexing.

Electromagnetic waves carrying orbital angular momentum (OAM) have been used for mode division multiplexing in free-space communication systems to increase both the capacity and the spectral efficiency. In the case of conventional wireless communication links using non-OAM beams, multipath effects caused by beam spreading and reflection from the surrounding objects affect the system performance. This paper presents the results of analysis, simulations, and measurements of multipath effects in a millimetre-wave communication link using OAM multiplexing at 28 GHz.

Orbital Angular Momentum-based Space Division Multiplexing for High-capacity Underwater Optical Communications.

To increase system capacity of underwater optical communications, we employ the spatial domain to simultaneously transmit multiple orthogonal spatial beams, each carrying an independent data channel. In this paper, we show up to a 40-Gbit/s link by multiplexing and transmitting four green orbital angular momentum (OAM) beams through a single aperture. Moreover, we investigate the degrading effects of scattering/turbidity, water current, and thermal gradient-induced turbulence, and we find that thermal gradients cause the most distortions and turbidity causes the most loss.

Demonstration of optical multicasting using Kerr frequency comb lines.

We experimentally demonstrate optical multicasting using Kerr frequency combs generated from a SiN microresonator. We obtain Kerr combs in two states with different noise properties by varying the pump wavelength in the resonator and investigate the effect of Kerr combs on multicasting. Seven-fold multicasting of 20 Gbaud quadrature phase-shift-keyed signals and four-fold multicasting of 16-quadrature amplitude modulation signals have been achieved when low-phase-noise combs are input into a periodically poled lithium niobate waveguide.