A power splitter with a wideband arbitrary splitting ratio, which provides flexibility and adaptability in forming photonic devices such as microring resonators and Mach–Zehnder interferometers, proves to be essential in photonic integrated circuits (PICs). We designed and fabricated a directional coupler-based power splitter with a wideband arbitrary splitting ratio and a microring resonator with a wideband uniform extinction ratio (ER) based on artificial gauge field (AGF) optimization. The neural network-aided inverse design method is applied to complete the target. Less than 0.9 dB power splitting variation and 1.6 dB ER variation have been achieved experimentally over a 100-nm bandwidth. Wideband performance, design efficiency, and device compactness are obtained by utilizing this optimization, which indicates great potential and universality in PIC applications.

Microcirculation imaging is crucial in understanding the function and health of various tissues and organs. However, conventional imaging methods suffer from fluorescence label dependency, lack of depth resolution, and quantification inaccuracy. Here, we report a light-sheet dynamic light-scattering imaging (LSH-DSI) system to overcome these shortcomings. LSH-DSI utilizes selected plane illumination for an optical sectioning, while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity. We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions. The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.

Confronting the escalating global challenge of counterfeit products, developing advanced anticounterfeiting materials and structures with physical unclonable functions (PUFs) has become imperative. All-optical PUFs, distinguished by their high output complexity and expansive response space, offer a promising alternative to conventional electronic counterparts. For practical authentications, the expansion of optical PUF keys usually involves intricate spatial or spectral shaping of excitation light using bulky external apparatus, which largely hinders the applications of optical PUFs. Here, we report a plasmonic PUF system based on heterogeneous nanostructures. The template-assisted shadow deposition technique was employed to adjust the morphological diversity of densely packed metal nanoparticles in individual PUFs. Transmission images were processed via a hash algorithm, and the generated PUF keys with a scalable capacity from 2875 to 243401 exhibit excellent uniqueness, randomness, and reproducibility. Furthermore, the wavelength and the polarization state of the excitation light are harnessed as two distinct expanding strategies, offering the potential for multiscenario applications via a single PUF. Overall, our reported plasmonic PUFs operated with the multidimensional expanding strategy are envisaged to serve as easy-to-integrate, easy-to-use systems and promise efficacy across a broad spectrum of applications, from anticounterfeiting to data encryption and authentication.

In recent years, many phase space distributions have been proposed, and one of the more independently interesting is the Bai distribution function (BDF). The BDF has been shown to interpolate between the instantaneous auto-correlation function and the Wigner distribution function, and be applied in linear frequency modulated signal parameter estimation and optical partial coherence areas. Currently, the BDF is only defined for continuous signals. However, for both simulation and experimental purposes, the signals must be discrete. This necessitates the development of a BDF analysis workflow for discrete signals. In this work, we analyze the sampling requirements imposed by the BDF and demonstrate their correctness by comparing the continuous BDFs of continuous test signals with their numerically approximated counterparts. Our results permit more accurate simulations using BDFs, which will be useful in applying them to problems such as partial coherence.

Optical phased arrays (OPAs) are crucial in beam-steering applications, particularly as transmitters in light detection and ranging and free-space communication systems. In this paper, we demonstrate a on-chip OPA that emits multiple orbital angular momentum (OAM) beams in different directions, each carrying unique topological charges. By superimposing a forked 1×3 Dammann grating on the grating array, six OAM beams with topological charges of ±3, ±4, and ±5 can be radiated from the OPA region. The OPA chip was fabricated on a silicon-on-insulator platform, and the simultaneous generation of multiple OAM beams was realized experimentally. The directions of these vortices can be steered by adjusting the wavelength of the input light and the bias voltages of the phase shifters, enabling a remarkable field of view (FOV) of 140 deg×40 deg within a 120-nm wavelength range. We pave the way for developing systems with ultrawide FOVs, improving the resolution of remote sensing and broadening the possibilities of free-space communications.

Plasmonic colors are attracting attention for their subwavelength small size, vibrant hues, and environmental sustainability beyond traditional pigments while suffering from angular and/or polarization dependency due to distinct excitations of lattice resonances and/or surface plasmon polaritons (SPPs). Here, we demonstrate the sodium metasurface-based plasmonic color palettes with polarization-independent wide-view angle (approximately >±60 deg in experiment and up to ±90 deg in theory) and single-particle-level pixel size (down to ∼60 nm) that integrate both pigment-like and structure coloring advantages, fabricated by the templated nanorod-pixelated solidification of wetted liquid metals. Such intriguing performances are mainly attributed to the particle plasmon dominant spectral response by steering the filling profile and thus the interplay between localized surface plasmons and SPPs. Combining low material cost, potentially scalable manufacturing process, and pronounced optical performance, the proposed sodium-based metasurfaces will provide a promising route for advanced color information technology.

Mid-infrared (MIR)-polarized thermal emission has broad applications in areas such as molecular sensing, information encryption, target detection, and optical communication. However, it is difficult for objects in nature to produce polarized thermal emission. Moreover, simultaneously generating and modulating broadband MIR thermal emission with both circular and linear polarization is even more difficult. We present a chiral plasmonic metasurface emitter (CPME) composed of asymmetric L-shaped and I-shaped antennas. The CPME consists of In3SbTe2 (IST) phase-change material (PCM) antennas, an Al2O3 dielectric layer, and an Au substrate. It is demonstrated that the CPME can selectively emit polarized light with different polarization states. Numerical simulations show that the CPME can achieve full Stokes parameter control of MIR thermal emission. By changing the state of the PCM IST, the spectral emissivity of 0 deg, 45 deg, 90 deg, and 135 deg linearly polarized (LP) lights and left-handed/right-handed circularly polarized (LCP/RCP) lights can be adjusted. In the crystalline state, the CPME exhibits the total degree of polarization (DoP) greater than 0.5 in the wavelength range of 3.4 to 5.3 μm, the degree of linear polarization (DoLP) greater than 0.4 in the range of 3.0 to 5.1 μm, and the degree of circular polarization (DoCP) greater than 0.4 in the range of 4.5 to 5.6 μm. The physical mechanism of polarized emission has been investigated fully based on the near-field intensity distribution and power loss distribution. Finally, the potential applications of the designed CPME in infrared polarization detection and antidetection are verified through numerical calculations.

Depolarizing behavior is commonly observed in most natural samples. For this reason, optical tools measuring the differences in depolarization response among spatially separated structures are highly useful in a wide range of imaging applications for enhanced visualization of structures, target identification, etc. One commonly used tool for depolarizing discrimination is the so-called depolarizing spaces. In this article, we exploit the combined use of two depolarizing spaces, the indices of polarization purity (IPP) and polarizance–reflection–transformation (PRT) spaces, to improve the capability of optical systems to identify polarization–anisotropy depolarizers. The potential of these spaces to discriminate among different depolarizers is first studied from a series of simulations by incoherently adding diattenuations or retarders, with some control parameters emulating samples in nature. The simulated results demonstrate that the proposed methods are capable of increasing differences among depolarizers beyond other well-known techniques. Experimentally, validation is provided by conducting diverse phantom experiments of easy interpretation and mimicking the stated simulations. As a useful application of our approach, we developed a model able to retrieve intrinsic microscopic information of samples from macroscopic polarimetric measurements. The proposed methods enable non-invasive, straightforward, macroscopic characterization of depolarizing samples, and may be of interest for enhanced visualization of samples in multiple imaging scenarios.

Diffractive optical neural networks (DONNs) have exhibited the advantages of parallelization, high speed, and low consumption. However, the existing DONNs based on free-space diffractive optical elements are bulky and unsteady. In this study, we propose a planar-waveguide integrated diffractive neural network chip architecture. The three diffractive layers are engraved on the same side of a quartz wafer. The three-layer chip is designed with 32-mm3 processing space and enables a computing speed of 3.1×109 Tera operations per second. The results show that the proposed chip achieves 73.4% experimental accuracy for the Modified National Institute of Standards and Technology database while showing the system’s robustness in a cycle test. The consistency of experiments is 88.6%, and the arithmetic mean standard deviation of the results is ~4.7%. The proposed chip architecture can potentially revolutionize high-resolution optical processing tasks with high robustness.

Quantum photonic processors are emerging as promising platforms to prove preliminary evidence of quantum computational advantage toward the realization of universal quantum computers. In the context of nonuniversal noisy intermediate quantum devices, photonic-based sampling machines solving the Gaussian boson sampling (GBS) problem currently play a central role in the experimental demonstration of quantum computational advantage. A relevant issue is the validation of the sampling process in the presence of experimental noise, such as photon losses, which could undermine the hardness of simulating the experiment. We test the capability of a validation protocol that exploits the connection between GBS and graph perfect match counting to perform such an assessment in a noisy scenario. In particular, we use as a test bench the recently developed machine Borealis, a large-scale sampling machine that has been made available online for external users, and address its operation in the presence of noise. The employed approach to validation is also shown to provide connections with the open question on the effective advantage of using noisy GBS devices for graph similarity and isomorphism problems and thus provides an effective method for certification of quantum hardware.