High-efficiency, cryogenic-compatible grating couplers on an AlN-on-sapphire platform through bottom-side coupling.

Sapphire is a commonly used substrate for wide-bandgap III-nitride photonic materials. However, its relatively high refractive index results in low transmission efficiency in grating couplers. Here, we propose and demonstrate that the transmission efficiency can be significantly enhanced by bottom-side coupling.

Insight into the Antibacterial Activities of Pyridinium-Based Cationic Pillar[5]arene with Controllable Hydrophobic Chain Lengths against .

The increasing number of infections caused by pathogenic bacteria has severely affected human society. More and more deaths were originated from Gram-positive methicillin-resistant (MRSA) infection each year. The potential and excellent bacteriostatic activity and resistance to biofilm formation of pillar[5]arene with different functional groups attract important attention to further study the relationship between antimicrobial activity and cytotoxicity by varying the length of the hydrophobic chain, the number of positive charges, and the hydrophobic/hydrophilic balance of the molecule.

New Family of Benzimidazole-Based Chitosan Derivatives against .

is the major fungus that causes blue mold and produces patulin, threatening human health. Due to health and environmental pollution concerns, chitosan (CS) has attracted more and more attention as a safer alternative to synthetic fungicides for the control of blue mold. In the present study, four different benzimidazole groups were introduced onto CS by the acylation reaction to obtain benzimidazole-based chitosan derivatives (R1b-R4b).

Heterogeneous sapphire-supported low-loss photonic platform.

Sapphire is a promising wideband substrate material for visible photonics. It is a common growth substrate for III-nitride light-emitting diodes and laser structures. Doped sapphires are important gain media foundational to the development of titanium-sapphire and ruby lasers.

Conjugation with glucagon like peptide-1 enables targeted protein degradation.

Lysosome-targeting chimeras (LYTACs) have emerged as a promising technique to extend the scope of targeted protein degradation to extracellular proteins, e.g., secreted proteins and membrane-anchored proteins.

Experimental demonstration of superresolution of partially coherent light sources using parity sorting: erratum.

The authors include references that appeared on arXiv during the preparation of their paper [Opt. Express29, 22034 (2021)10.1364/OE.

Direct Tomography of High-Dimensional Density Matrices for General Quantum States of Photons.

Quantum-state tomography is the conventional method used to characterize density matrices for general quantum states. However, the data acquisition time generally scales linearly with the dimension of the Hilbert space, hindering the possibility of dynamic monitoring of a high-dimensional quantum system. Here, we demonstrate a direct tomography protocol to measure density matrices of photons in the position basis through the use of a polarization-resolving camera, where the dimension of density matrices can be as large as 580×580 in our experiment.

Experimental demonstration of superresolution of partially coherent light sources using parity sorting.

Analyses based on quantum metrology have shown that the ability to localize the positions of two incoherent point sources can be significantly enhanced over direct imaging through the use of mode sorting. Here we theoretically and experimentally investigate the effect of partial coherence on the sub-diffraction limit localization of two sources based on parity sorting. With the prior information of a negative and real-valued degree of coherence, higher Fisher information is obtained than that for the incoherent case.

Tunable Doppler shift using a time-varying epsilon-near-zero thin film near 1550 nm.

We experimentally investigate the tunable Doppler shift in an 80 nm thick indium-tin-oxide (ITO) film at its epsilon-near-zero (ENZ) region. Under strong and pulsed excitation, ITO exhibits a time-varying change in the refractive index. A maximum frequency redshift of 1.

Adiabatic Frequency Conversion Using a Time-Varying Epsilon-Near-Zero Metasurface.

A time-dependent change in the refractive index of a material leads to a change in the frequency of an optical beam passing through that medium. Here, we experimentally demonstrate that this effect-known as adiabatic frequency conversion (AFC)-can be significantly enhanced by a nonlinear epsilon-near-zero-based (ENZ-based) plasmonic metasurface. Specifically, by using a 63-nm-thick metasurface, we demonstrate a large, tunable, and broadband frequency shift of up to ∼11.

Confocal super-resolution microscopy based on a spatial mode sorter.

Spatial resolution is one of the most important specifications of an imaging system. Recent results in the quantum parameter estimation theory reveal that an arbitrarily small distance between two incoherent point sources can always be efficiently determined through the use of a spatial mode sorter. However, extending this procedure to a general object consisting of many incoherent point sources remains challenging, due to the intrinsic complexity of multi-parameter estimation problems.

A 1,8-naphthalimide-based lysosome-targeting dual-analyte fluorescent probe for the detection of pH and palladium in biological samples.

Fluorescent probes containing 1,8-naphthalimide dyes have been used to detect biomolecules in the environmental and biological fields. However, most of the probes only exhibit single fluorescent output to one analyte, making them insufficient for detection of more analytes. Herein, we developed a novel 1,8-naphthalimide-based lysosome-targeting dual-analyte sensitive fluorescent probe (DPPP) for the detection of pH and palladium (Pd) using two different emissive channels.

High-fidelity spatial mode transmission through a 1-km-long multimode fiber via vectorial time reversal.

The large number of spatial modes supported by standard multimode fibers is a promising platform for boosting the channel capacity of quantum and classical communications by orders of magnitude. However, the practical use of long multimode fibers is severely hampered by modal crosstalk and polarization mixing. To overcome these challenges, we develop and experimentally demonstrate a vectorial time reversal technique, which is accomplished by digitally pre-shaping the wavefront and polarization of the forward-propagating signal beam to be the phase conjugate of an auxiliary, backward-propagating probe beam.

Compensation-free high-dimensional free-space optical communication using turbulence-resilient vector beams.

Free-space optical communication is a promising means to establish versatile, secure and high-bandwidth communication between mobile nodes for many critical applications. While the spatial modes of light offer a degree of freedom to increase the information capacity of an optical link, atmospheric turbulence can introduce severe distortion to the spatial modes and lead to data degradation. Here, we demonstrate experimentally a vector-beam-based, turbulence-resilient communication protocol, namely spatial polarization differential phase shift keying (SPDPSK), that can reliably transmit high-dimensional information through a turbulent channel without the need of any adaptive optics for beam compensation.

Performance of real-time adaptive optics compensation in a turbulent channel with high-dimensional spatial-mode encoding.

The orbital angular momentum (OAM) of photons is a promising degree of freedom for high-dimensional quantum key distribution (QKD). However, effectively mitigating the adverse effects of atmospheric turbulence is a persistent challenge in OAM QKD systems operating over free-space communication channels. In contrast to previous works focusing on correcting static simulated turbulence, we investigate the performance of OAM QKD in real atmospheric turbulence with real-time adaptive optics (AO) correction.

Broadband frequency translation through time refraction in an epsilon-near-zero material.

Space-time duality in paraxial optical wave propagation implies the existence of intriguing effects when light interacts with a material exhibiting two refractive indexes separated by a boundary in time. The direct consequence of such time-refraction effect is a change in the frequency of light while leaving the wavevector unchanged. Here, we experimentally show that the effect of time refraction is significantly enhanced in an epsilon-near-zero (ENZ) medium as a consequence of the optically induced unity-order refractive index change in a sub-picosecond time scale.

Simultaneous turbulence mitigation and channel demultiplexing for two 100 Gbit/s orbital-angular-momentum multiplexed beams by adaptive wavefront shaping and diffusing.

We experimentally demonstrate simultaneous turbulence mitigation and channel demultiplexing in a 200 Gbit/s orbital-angular-momentum (OAM) multiplexed link by adaptive wavefront shaping and diffusing (WSD) the light beams. Different realizations of two emulated turbulence strengths (the Fried parameter ${r_0} = 0.4,\,1.

Flow Measurement of Oil-Water Two-Phase Flow at Low Flow Rate Using the Plug-in Conductance Sensor Array.

In order to improve the flow measurement accuracy of oil-water two-phase flow at low flow rate, this paper presents a plug-in conductance sensor array (PICSA) for the measurement of water holdup and cross-correlation velocity. Due to the existence of the insert body in PICSA, the effect of slippage and the non-uniform distribution of dispersed phase on the measurement of oil-water two-phase flow at low flow rate can be reduced. The finite element method is used to analyze the electric field distribution characteristics of the plug-in conductance sensor, and the sensor geometry is optimized.

Using all transverse degrees of freedom in quantum communications based on a generic mode sorter.

The dimension of the state space for information encoding offered by the transverse structure of light is usually limited by the finite size of apertures. The widely used orbital angular momentum (OAM) number of Laguerre-Gaussian (LG) modes in free-space communications cannot achieve the theoretical maximum transmission capacity unless the radial degree of freedom is multiplexed into the protocol. While the methodology to sort the radial quantum number has been developed, the application of radial modes in quantum communications requires an additional ability to efficiently measure the superposition of LG modes in the mutually unbiased basis.

Realization of a scalable Laguerre-Gaussian mode sorter based on a robust radial mode sorter.

The transverse structure of light is recognized as a resource that can be used to encode information onto photons and has been shown to be useful to enhance communication capacity as well as resolve point sources in superresolution imaging. The Laguerre-Gaussian (LG) modes form a complete and orthonormal basis set and are described by a radial index p and an orbital angular momentum (OAM) index ℓ. Earlier works have shown how to build a sorter for the radial index p or/and the OAM index ℓ of LG modes, but a scalable and dedicated LG mode sorter which simultaneous determinate p and ℓ is immature.

Hermite-Gaussian mode sorter.

The Hermite-Gaussian (HG) modes, sometimes referred to as transverse electromagnetic modes in free space, form a complete and orthonormal basis that have been extensively used to describe optical fields. In addition, these modes have been shown to be helpful in enhancing information capacity of optical communications as well as achieving super-resolution imaging in microscopy. Here we propose and present the realization of an efficient, robust mode sorter that can sort a large number of HG modes based on the relation between HG modes and Laguerre-Gaussian (LG) modes.

Digital spiral object identification using random light.

Photons that are entangled or correlated in orbital angular momentum have been extensively used for remote sensing, object identification and imaging. It has recently been demonstrated that intensity fluctuations give rise to the formation of correlations in the orbital angular momentum components and angular positions of random light. Here we demonstrate that the spatial signatures and phase information of an object with rotational symmetries can be identified using classical orbital angular momentum correlations in random light.

Sorting Photons by Radial Quantum Number.

The Laguerre-Gaussian (LG) modes constitute a complete basis set for representing the transverse structure of a paraxial photon field in free space. Earlier workers have shown how to construct a device for sorting a photon according to its azimuthal LG mode index, which describes the orbital angular momentum (OAM) carried by the field. In this paper we propose and demonstrate a mode sorter based on the fractional Fourier transform to efficiently decompose the optical field according to its radial profile.

Labeled RFS-Based Track-Before-Detect for Multiple Maneuvering Targets in the Infrared Focal Plane Array.

The problem of jointly detecting and tracking multiple targets from the raw observations of an infrared focal plane array is a challenging task, especially for the case with uncertain target dynamics. In this paper a multi-model labeled multi-Bernoulli (MM-LMB) track-before-detect method is proposed within the labeled random finite sets (RFS) framework. The proposed track-before-detect method consists of two parts-MM-LMB filter and MM-LMB smoother.