In computed tomography (CT) slip rings and similar applications, effective communication in rotating systems is critical, yet conventional slip ring methods are plagued by electromagnetic interference, low speeds, and high costs. In this work, we propose, to our knowledge, a novel fiber side-emitting communication system that employs the side-emitting fiber (SEF) as the optical transmitter to address these issues. An optical antenna with a gain of 9.6 dB enhances coupling efficiency, and a new SEF transmission model is developed. Experimental results demonstrate real-time data transfer at 1.25 Gbps with a bit error rate below 1 × 10-12, offering a robust and efficient solution for high-speed wireless communications in dynamic applications.

We comprehensively characterized the birefringence distribution of polarization-maintaining fibers (PMFs) in the fiber-optic gyroscopes using an enhanced Brillouin dynamic grating (BDG). This method enabled the quantitative analysis of the birefringence variations along the fiber, including those induced by temperature, axial strain, and transverse strain. Experimental results revealed that the birefringence coefficients of axial strain and temperature were 0.857 × 10-8/µε and -4.7 × 10-7/°C for the PMF coils, respectively. When PMFs are cross-wound in a layered configuration within the fiber-optic gyroscopes, transverse-strain will significantly impact the birefringence distribution. These findings offer valuable technical guidance for the design and manufacturing of high-precision fiber-optic gyroscopes.

Cold atoms play an important role in fundamental physics, precision timekeeping, quantum sensing, and quantum computing. The production of cold atoms requires magneto-optical traps (MOTs), but current MOTs consist of a variety of complex and bulky optical infrastructures that hamper their practical application. The development of integrated photonic circuits offers the opportunity to achieve integrated MOTs. Here, we take advantage of the ultra-low loss of the silicon nitride platform to design a grating outcoupler for coupling beams from waveguides to free space. The device operates at a wavelength of 780 nm with an experimental emission angle of 24.38°. Additionally, by appropriately designing the positions of the grating outcouplers on the chip, we propose an on-chip emission system to demonstrate the MOT application. The intersection area is about 2 mm × 2 mm at a height of 6 mm on the chip. Our work provides the possibility of realizing on-chip MOTs.

Mid-infrared (mid-IR) silicon photonic integrated circuits have drawn considerable interest to date. However, previous devices are typically designed on silicon waveguide configurations with hundreds of nanometers in thickness, hindering their application in sensing. Here, we demonstrated a suspended nanomembrane silicon (SNS) microring resonator (MRR) at 3.27 µm wavelengths with a subwavelength grating coupler. Our experimental results show that the SNS MRR showcases a quality factor of ∼3500 with a giant confinement factor of 0.89 and reduced thermal sensitivity of 0.07 nm/°C. To our knowledge, the study opens a new avenue to developing mid-IR silicon devices for sensing applications.

Photonic-crystal surface-emitting lasers (PCSELs) are considered as next-generation semiconductor lasers because they can operate in a high-power single mode. However, these devices are not suitable for low-threshold high-speed operation because they often require a long cavity length to achieve low loss. In this paper, we break this limit and demonstrate very low-threshold operation of the PCSELs for their high-speed application, using a triple-lattice photonic-crystal structure with a 100 µm cavity length. Low threshold currents of 29 mA at 10°C and 36 mA at 25°C under continuous wave (CW) operation were realized, which is comparable to the traditional high-speed distributed feedback (DFB) Bragg edge-emitting lasers. The far-field divergence angles defined by 1/e2 power were respectively 3.84° and 1.63° along the x- and y-directions. A small-signal modulation bandwidth of 5.8 GHz was obtained. By further optimizing the mesa size, the threshold current was decreased to 12 mA, which, to the best of our knowledge, is the lowest threshold current reported for PCSELs so far.

In recent years, the perfect vortex beam with independent wavefront spiral correlation has attracted extensive attention since its beam diameter is independent of topological charge. Perfect vortex beams are expected to make significant progress in optical fiber communications, particle manipulation, quantum information, and other areas. Traditional optical devices are difficult to integrate into the system due to their large size. In this paper, we design and realize a perfect vortex beam with a high reflection efficiency of 90.17% by an all-dielectric metasurface through a Pancharatnam–Berry (PB) phase modulation structure. The cross-polarization conversion efficiency measured by experiment is 89.81%. By modulating the parameter r0 in the phase function, we can achieve flexible manipulation of topological charges and ring diameters. In addition, we also demonstrate the generation of a four-channel perfect vortex beam array based on the Dammann grating, with a beam uniformity of 40%. Our research will be of great significance for the realization of compact and multifunctional on-chip integrated photonic devices.

In this Letter, we explore the interplay between topological defects and resonant phenomena in photonic crystal slabs, focusing on quasi-flatband resonances and bound states in the continuum (BICs). We identify anisotropic quasi-flatband resonances and isotropic quasi-flatband symmetry-protected BICs that exist in coupled topological defects characterized by nontrivial 2D Zak phases, originating from monopole, dipole, and quadrupole corner modes within second-order topological insulator systems. These topological defect modes, whose band structures are described using a tight-binding model, exhibit distinctive radiative behavior due to their symmetry and multipolar characteristics. Through far-field excitation analysis, we demonstrate the robustness and accessibility of these modes in terms of angular and spectral stability. Furthermore, we investigate potential applications of the quasi-flatband resonances in light–matter interactions, including optical forces, second-harmonic generation, and strong coupling, which exhibit robust performance under varying illumination angles. These findings offer new opportunities for precise control over light–matter interactions.

For the first time, to our knowledge, the cascading effects of self-phase modulation and second-harmonic generation (SPM-SHG) in a nonlinear optical medium were used to conveniently convert a near-infrared ultrafast laser with a fixed center wavelength into a visible to deep-ultraviolet (DUV) laser with a continuously tunable wavelength. When a β-BaB2O4 (BBO) crystal was used as the nonlinear optical medium, and a Ti:sapphire laser (800 nm, 38 fs) was used as the fundamental light source, the output wavelength had a tunable range of 225–460 nm, and the highest optical conversion efficiency reached 18.1% at 361 nm. For a 1030 nm fundamental light source, the shortest output wavelength was also 225 nm by one-step frequency conversion of the BBO crystal. By further frequency conversions, the tunable wavelength can extend to the vacuum ultraviolet (VUV) waveband, as short as 193 nm. These results demonstrated that SPM-SHG could be used as an extremely simple and effective frequency conversion method to obtain a wideband tunable ultraviolet laser.

Autofocusing beams are powerful photonic tools for manipulating micro/nanoparticles. Here, we propose a special type of dislocated-superimposed swallowtail vortex beam (DSVB) and analyze its propagation properties and optical manipulating capability. By modulating the parameters of the superposition number N and the topological charge l, DSVBs show asymmetric autofocusing propagation phenomena and unconventional orbital angular momentum (OAM), especially for opposite topological charges. Furthermore, when N = |l|, DSVBs form multiple solid focuses while preserving OAM during propagation, suggesting potential applications in multi-point trapping and rotational manipulation. These results deepen the understanding of autofocusing and OAM behaviors, highlighting DSVBs’ potential as photonic tools for optical manipulation.

Structured illumination microscopy (SIM) is a pivotal technique for dynamic subcellular imaging in live cells. Conventional SIM reconstruction algorithms depend on accurately estimating the illumination pattern and can introduce artifacts when this estimation is imprecise. Although recent deep-learning-based SIM reconstruction methods have improved speed, accuracy, and robustness, they often struggle with out-of-distribution data. To address this limitation, we propose an awareness-of-light-field SIM (AL-SIM) reconstruction approach that directly estimates the actual light field to correct for errors arising from data distribution shifts. Through comprehensive experiments on both simulated filament structures and live BSC1 cells, our method demonstrates a 7% reduction in the normalized root mean square error (NRMSE) and substantially lowers reconstruction artifacts. By minimizing these artifacts and improving overall accuracy, AL-SIM broadens the applicability of SIM for complex biological systems.

Although single-pixel correlated imaging has the capability to capture images in complex environments, it still encounters challenges such as high computational complexity, limited imaging efficiency, and reduced imaging quality under low-light conditions. We innovatively propose a symmetrically related random phase-based correlated imaging method, which reduces the number of required random scattering media, enhances computational efficiency, and mitigates system noise interference. Single-pixel correlated imaging can be completed within 2 min using this approach. The experiments demonstrated that both the constructed dual-path thermal-optical correlated imaging system and the single-path computational correlated imaging system achieved high-quality imaging even under low-light conditions.