A deeper understanding of room temperature polariton condensed phases is essential for advancing quantum applications. Spin degrees of freedom inherent in polariton particles manifest themselves in the form of spinor condensation, which has been demonstrated only at cryogenic temperatures in the past. Herein, we demonstrate room-temperature spinor polariton condensation in a lead-halide perovskite microcavity under nonresonant optical excitation. The crystalline anisotropy of the perovskite induces a linear polarization splitting of the lower polariton modes, and, above the condensation threshold, nonlinear polariton-polariton interactions drive the formation of elliptically polarized condensates. The condensation dynamics are analyzed using a spin-dependent Gross-Pitaevskii model, which provides a qualitative framework for understanding the experimentally observed polarization evolution and two-stage threshold behavior. Our findings pave the way for all-optical control of polariton spin states at room temperature, opening a path toward scalable polaritonic quantum devices.

ABSTRACT We report integrated mode‐ and polarization‐division multiplexing components on a high‐index‐contrast Ge 28 Sb 12 Se 60 (GeSbSe) chalcogenide‐glass‐loaded thin‐film lithium niobate on insulator (LNOI) platform operating across the 1500–1570 nm wavelength range. By leveraging the direction‐dependent birefringence of x‐cut LNOI together with the strong optical confinement provided by the GeSbSe overlayer, we experimentally demonstrate a four‐channel mode (de)multiplexer (MDM) and an asymmetric‐directional‐coupler‐based polarization splitter–rotator (PSR). Over the full band, the MDM achieves insertion losses below 0.97, 0.31, 2.36, and 3.21 dB for the TE 0 –TE 3 channels, with intermodal crosstalk better than −18.3, −19.2, −14.9, and −16.3 dB, respectively. The PSR exhibits insertion losses of 1.67 dB (TM 0 input) and 1.81 dB (TE 0 input), together with extinction ratios exceeding 20.7 and 31.6 dB. These results validate GeSbSe‐on‐LNOI as a scalable platform for broadband low‐loss multidimensional multiplexing in high‐capacity photonic integrated circuits.

The emergence of altermagnets establishes a new paradigm for multiferroics. Unlike conventional multiferroics that rely on direct magnetoelectric coupling, multiferroic altermagnets host a crystal-symmetry-mediated magnetoelectric interaction that is intrinsically more efficient and robust. Among candidate material platforms, layered perovskites are particularly appealing owing to their structural diversity and synthetic versatility. However, magnetoelectric properties at the two-dimensional scale remain largely unexplored, hindering their applicability in miniaturized, highly integrated devices. Here, we systematically investigate the dimensional evolution of ferroelectric polarization and magnetism in perovskite systems through symmetry analysis. We demonstrate that altermagnetism can persist in the two-dimensional limit, yet is strongly constrained by the magnetic configuration-with only C-type antiferromagnetic order supporting it. On the basis of mode-decomposition calculations, we further reveal that symmetry-restricted multimode couplings simultaneously govern ferroelectric polarization and altermagnetic spin splitting. Finally, combined with first-principles calculations, we propose several strategies to lift the magnetic-configuration constraint, extending the range of viable altermagnetic systems. These results underscore the critical role of dimensionality in symmetry-driven magnetoelectric coupling in perovskite altermagnets and pave the way toward next-generation electrically controlled spintronic and multiferroic devices.

To overcome the persistent challenges in current angle-selective technologies, particularly the trade-off between structural compactness and dynamic tunability, a one-dimensional magnetic photonic crystal is introduced. The proposed structure leverages the magnetoplasmonics of epsilon-near-zero (ENZ) Indium Arsenide to achieve a sharp angular cutoff via magnetically tunable total internal reflection. The proposed configuration, composed of ENZ Indium Arsenide and dynamic anti-reflection structures (AFS), is designed to operate based on the principles of total internal and Bragg reflection. Theoretical calculations, performed via the transfer matrix method, show that the engineered AFS mitigates material resonance defects. This creates a rectangular transmission window surpassing 0.9 across a ± 55° wide-angle range and demonstrates exceptional polarization and angular robustness. Moreover, the application of an external magnetic field enables the dynamic separation of transverse electric (TE) and transverse magnetic (TM) waves. The magnetic field selectively compresses the angular passband of TM waves through the Lorentz force, while TE waves remain fundamentally unperturbed, thereby allowing for dynamic switching among three operational modes comprising dual polarization transparency, polarization separation, and total blocking. Furthermore, this magneto-optical effect is also evident in the frequency domain, where the elevation of the TM wave passband to higher frequencies creates a tunable TE passband filter. Consequently, the proposed design offers an innovative framework for high-performance, multifunctional optical switches, polarization splitters, and dynamic filters.

The scalability of integrated photonic systems for next-generation datacom and sensing applications is fundamentally limited by the strong polarization dependence of high-confinement waveguides. While silicon nitride (Si3N4) has emerged as a premier platform for low-loss, broadband passive functionalities, mitigating polarization sensitivity typically requires complex polarization diversity schemes that increase footprint and insertion loss. We demonstrate a monolithic, polarization-insensitive Si3N4 platform that eliminates the need for polarization splitters or rotators by engineering the waveguide geometry to suppress birefringence at the fundamental mode level. By utilizing a near-square cross-section (800 nm × 800 nm), we achieve nearly identical effective and group indices for TE and TM modes across a broad spectral range. Leveraging this platform, we present two key devices: a broadband 1 × 2 optical switch and a 1 × 4 coarse wavelength division multiplexing (CWDM) demultiplexer. The optical switch operates across the C and L bands (1500-1620 nm) with insertion losses below 1.52 dB and polarization-dependent losses (PDL) below 1.53 dB. The CWDM device exhibits superior performance with insertion losses below 1.14 dB and PDL below 0.75 dB. This approach offers a robust, low-complexity pathway for polarization-agnostic photonic processing in high-capacity optical networks.

Single Molecule Orientation and Localization Microscopy (SMOLM) aims at simultaneously measuring the position and orientation of single molecules, generating orientation-encoded super-resolved images by estimating both their 3D mean orientation and the extent of their angular fluctuations (wobble). Most existing SMOLM approaches rely on the engineering of single molecules’ point spread functions, which requires complex optical setups and long computational times that can be an obstacle in dense cellular environments with high detection density and challenging imaging conditions. In this work, we propose a simpler and effective method named 4polar3D, based on the estimation of single molecule intensities projected onto four polarized channels with controlled numerical apertures. This strategy enables 3D orientation measurements of single molecules within a 0-180° azimuthal range in addition to their angular range of fluctuations and their 2D localization, using a setup requiring minimal alignment complexity. It is moreover based on pure intensity-estimation, making data processing considerably faster than complex PSF shape analysis and relatively insensitive to geometrical aberrations. We demonstrate that 4polar3D can resolve nanoscale molecular organization in whole cells’ crowded structures, uncovering 3D-oriented actin filament networks in densely packed lamellipodia and podosomes.

High-precision detection of hazardous gases with low refractive indices ranging from 1.000 to 1.100, specifically including methane, carbon monoxide, and sulfur dioxide, is critical for industrial safety, yet conventional sensors often suffer from limited sensitivity and severe thermal cross-sensitivity. This work presents a Magneto-Optical Differential Photonic Crystals Sensor (MO-DPCS) utilizing indium antimonide (InSb) to address these constraints. Employing the Multi-Objective Dragonfly Algorithm (MODA), the system was inversely optimized to maximize magneto-optical polarization splitting while rigorously maintaining an ultra-high transmission efficiency. Crucially, an angular interrogation architecture operating under oblique incidence was established to maximize the magneto-optical non-reciprocity, where the detection was realized by fixing the terahertz source frequency and monitoring the precise angular displacements of the steep spectral edges. A differential detection technique was employed to utilize the non-reciprocal phase changes wherein Transverse Electric (TE) and Transverse Magnetic (TM) modes display contrasting kinematic characteristics in the presence of an external magnetic field. The findings indicate that with an adjusted magnetic field of 0.033 T, the MO-DPCS attains an exceptional differential sensitivity of 30.8°/RIU, much above the 0.8°/RIU seen in the unmagnetized condition. The differential approach efficiently eliminates common-mode thermal noise, minimizing temperature-induced drift to below 0.35° across a 1 K range. The suggested MO-DPCS offers a robust, self-referencing solution for stable and high-sensitivity gas sensing applications with a detection limit of 4.18 × 10-4 RIU.

Exciton-polaritons are quasiparticles that are defined by the interaction between semiconductors and optical cavities. The ultra-low effective mass of polariton quasi-particles from its photonic component facilitates the polariton lasing processes at high temperature. The fixing of initial exciton polarization necessitates a method to achieve a stable polarized output. In this paper, we demonstrate the polarization-fixed polariton condensation lasing at room temperature, which is based on the anisotropy inherent in the gain media crystal structure. At the threshold (Pth = 25 kW cm−2), emission intensity exhibits nonlinear growth, and linewidth undergoes a sharp contraction. The dispersion curve of TE–TM polarization splitting was fitted by using a coupled Lorentz resonator model. Its validity was verified by adjusting the detuning amount to match experimental results. Moreover, the perpendicular emission directions of TE and TM polarization are indicated by reciprocal space imaging. The significance of first-order coherence of polariton lasing is explained qualitatively via the Michelson interferometer. Our results provide a feasible route for the development of polariton optoelectronic devices with tunable polarization degrees of freedom.

In the present work, we investigate the coupling and decoupling between the co-polarized and cross-polarized TE/TM modes under the combined influence of applied voltage and optic axis orientation in anisotropic uniaxial one-dimensional photonic crystals. The proposed structure consists of silicon dioxide and titanium dioxide as the periodic layers and barium titanate as the defect layer. Unlike the previous work, where either a single input polarization is considered or an inconsistent permittivity tensor has been employed to account for the simultaneous effects of the external electric field and optic axis rotation, here a physically consistent formulation is presented where the electro-optic effect and optic axis rotation are applied in different coordinate frames. This approach reveals that a polarized TE (or TM) input light splits into TE and TM output lights at specific optic axis angles. At the optic axis angle of 45°, the splitting modes have symmetry in their transmission. The voltage applied across the defect compensates for the effect of the optic axis angle and enables voltage-controlled suppression of polarization coupling. Additionally, it introduces tunability in the TM modes, whereas the incident angle provides tunability for all the modes. When the voltage is 40 V or greater, the coupling effect diminishes. These results provide an accurate physical understanding of tunable polarization control in one-dimensional photonic crystals and support the design of voltage-tunable optical filters and polarization-selective photonic devices, with the further possibility of advancing into the theoretical modeling of higher-dimensional photonic crystals.

Abstract The Rashba effect, originating from spin-orbit interaction and crystal asymmetry, enables electric-field control of electron spins, making materials with strong Rashba splitting near the Fermi level attractive for spintronics. Using first-principles calculations, we identify asymmetric Bi 2 O 2 Se monolayer as a semiconductor exhibiting large Rashba splitting. Its structure induces a work function difference (Δ ϕ ) of 3.25 eV, dipole moment of 0.32 D, and a small band gap of 0.30 eV. The conduction band shows Rashba energy E R = 33.6 meV and coupling constant α R = 10.56 eV Å with circular spin texture around the Γ point. The monolayer remains mechanically stable under ± 10% strain, while strain and electric fields (≤0.3 V/Å) reversibly tune polarization and Rashba splitting. A finite out-of-plane spin component ( S z ) emerges from anisotropic SOC, demonstrating experimentally feasible and controllable spin-texture modulation. Both E R and α R increase under tensile strain, highlighting Bi 2 O 2 Se’s potential for high-efficiency spin-field-effect transistors and advanced semiconductor spintronics.

Two-dimensional Janus transition-metal dihalides RuXY (X, Y = Cl, Br, I) constitute a class of van der Waals multiferroic materials with the coexistence of sliding ferroelectricity and interlayer antiferromagnetism. Here, we report the sliding ferroelectricity and ferroelectricity-valley coupling in Janus RuXY bilayers based on first-principles calculations. The out-of-plane ferroelectric polarization, which originates from vertical charge transfer induced by broken mirror symmetry, can be reversed through interlayer sliding. The relative electronegativity of the halogens strongly determines the enhancements or reductions of the polarizations of Janus RuXY bilayers. In addition, the valley polarization and valley splitting at the K/K' points in Janus RuXY bilayers are inverted upon ferroelectric switching due to interlayer sliding, demonstrating a potential ferroelectricity-valley coupling mechanism - the regulation of the valley state by the sliding ferroelectric polarization. Furthermore, atomically projected band structures illustrate that Ru atoms dominate the valley behavior, while contributions from halogen atoms are negligible. The coexistence of low switching energy and strong ferroelectricity-valley coupling makes Janus RuXY bilayers a promising platform for energy-efficient multiferroic and valleytronic devices.

In this Letter, we present an ultra-slow-light metasurface driven by multiple symmetrically protected BIC (SP-BIC) that generates three EIT windows based on three wavelength-stabilized quasi-BIC (QBIC) in two distinct methods. The first EIT is indirectly excited by coupling a QBIC with a leakage mode, resulting in a maximum group delay of 105 ps. The latter two EITs are directly excited by the QBIC, producing group delays as high as 2771 ps, which is 2-3 orders of magnitude larger than previously reported. As a sensor, the metasurface achieves a maximum sensing sensitivity of 415.5 nm/RIU. Furthermore, the first EIT is situated at 1550 nm, where the transverse magnetic (TM) light is fully transmitted, while the transverse electric (TE) light is fully reflected. Metasurface can function as a perfect polarization splitter and filter, and this result can be extended to encompass the entire optical communication spectrum from the O band to U band.

Wavelength independent manipulation of the state of polarization is essential for realizing broadband photonic integrated circuits (PICs). We present here, for the first time, the use of compact total internal reflection (TIR) mirrors in silicon waveguides to achieve wavelength-independent (within the limits of material dispersion), polarization-dependent phase shifts, which are also tolerant to fabrication errors. A potential application area is polarization splitters operating on a broad wavelength range that has been the focus of our first proof-of-concept demonstration. Our devices achieved a 15 dB polarization extinction ratio for 80 nm bandwidth for TE and TM polarized light. These broadband polarization splitters, when combined with polarization rotators, can be used to develop all-silicon fully integrated isolators and circulators.

Inverse design promotes the miniaturization of integrated photonic devices by leveraging subwavelength structures. Based on the physics-constrained inverse design (PCID) method, we propose an ultra-compact polarization beam splitter (PBS), featuring integrated coupling gratings inversely designed to simultaneously and efficiently couple TE and TM modes. This PBS consists of a standard silicon-on-insulator (SOI) substrate and a two-dimensional digital metasurface composed of tunable air-silicon column structures. This achieves efficient polarization splitting within a compact footprint of 5 × 2.7 μm2. The integrated coupling gratings, inversely designed for simultaneous and efficient coupling of both TE and TM modes, significantly mitigate fabrication errors and ensure consistent measurement conditions for each polarization state. Consequently, experimental measurements closely match our simulated predictions, demonstrating low insertion losses(-1.58 dB for TE mode and -1.65 dB for TM mode) and high extinction ratios over an 80 nm bandwidth covering the entire C-band.

This paper describes how resonance spectra and mode profiles can be used to characterize and quantify the mode-shaping effects in open-access plano-concave optical microcavities. The presented semi-analytic theory is based on the application of perturbation theory to the round-trip evolution of the optical field. It includes various mirror-shape and nonparaxial effects and extends the nonparaxial theory presented in [Exter , ] and verified in [Koks , ] to the common case of an anisotropic Gaussian mirror. The presented measurements and analyses of resonance spectra and mode profiles demonstrate how the different mode-shaping effects can be individually distinguished and quantified. Spin-orbit coupling, which is one of the nonparaxial effects, is prominently visible in the intriguing polarization patterns of the resonant modes, while polarization tomography yields the shape-induced birefringence and associated polarization splitting of the fundamental modes.

Abstract High‐power, high‐energy ultrafast vortex lasers offer significant potential across a wide range of applications. This study introduces a novel and adaptable method for generating high‐power picosecond vortices using a dual‐cavity thin‐disk regenerative amplifier via polarization splitting. The design enables precise, real‐time control of vortex mode purity via dynamic modulation of mode competition within the polarization‐splitting cavities. The amplifier produces high‐purity picosecond vortex pulses, delivering an average power of 102 W and a pulse energy of 1.02 mJ at a repetition rate of 100 kHz. A comprehensive 2D rate‐equation model is developed to investigate system dynamics and determine optimal operating parameters. This approach offers a robust, scalable, and versatile platform for generating high‐power ultrafast Laguerre–Gaussian vortex pulses with precise mode control, providing a strong foundation for the development of next‐generation intelligent vortex laser systems.

Compared with computational imaging, direct imaging is still a concern since it provides more intuitive and reliable spatiotemporal information of the target. The paper presents a single-shot ultrafast framing direct imaging based on polarization-spatial-encoding via non-collinear optical parametric amplification (OPA) with remarkable imaging seed and spatiotemporal resolutions. Here, a 2 × 4 architecture is designed for eight optical parametric amplifiers to get eight frames by polarization splitting. This architecture effectively suppresses signal depolarization and diffraction effects, particularly mitigating nonlinear effects during pump propagation, thus enhancing imaging quality compared with a 1 × 8 design. Targeted with laser-induced air plasma, our experiments verify that the single-shot imaging system has carried out 8-frame direct imaging by 25 fs temporal resolution, 40 trillion frames per second (Tfps) effective frame rate, and beyond 25.6 lp/mm spatial resolution over a 10 × 10 mm2 field-of-view. The experimental results also show the capture of richer spatiotemporal details of air plasma in the early stage (0∼3.6 ps) after excitation. The temporal window can be flexibly expanded by changing the frame interval. This work provides a powerful tool for accurately understanding dynamic processes on the femtosecond to picosecond scale for non-repeatable or random dynamic scenarios.

Tamm plasmon polariton (TPP) is a cavity mode confined in a multilayer structure consisting of a distributed Bragg reflector and a metallic layer. It can be excited with varied polarizations and any angle of incidence, attracting significantly growing attention recently. To date, the majority of TPP structures are constructed with gold or silver. The qualification of aluminum as an alternative material for TPP mode is pending. Here, we show that it is possible to realize comparable characteristics with aluminum (Al)-based TPP structures, in terms of spectral behavior, quality factor (Q-factor), and electric field enhancement. Experimentally, we demonstrate that Al is qualified for the TPP mode with an exceptionally narrow linewidth (∼17 nm), high Q-factor (∼35.8), and moderate field enhancement (2.38-fold) in the visible band. Moreover, we found that Al-based TPP structures are more tolerant to polarization divergences (with a polarization splitting of only 11 nm at the incidence angle of 50°) compared to noble metal counterparts. This work paves the way toward the usage of Al as a viable and low-cost material for TPP devices beyond noble metals.

Multifunctional integrated photonic devices are essential for advancing high-density photonic circuits. In this work, we propose and experimentally demonstrate an ultra-broadband device that simultaneously enables polarization separation and 3 dB power splitting for the TM mode. The design exploits the anisotropic properties of subwavelength gratings (SWGs), incorporating transverse and longitudinal SWGs in both transition and coupling regions. TE-polarized light is guided through the central path, while TM-polarized light is symmetrically split into lateral SWGs. The device functions as a broadband polarizer for TE input (1260-1675 nm), with excess loss (EL) below 1 dB and crosstalk (CT) below -20 dB. For TM input, 3 dB splitting is achieved over 1400-1660 nm, with EL < 0.5 dB and CT < -22 dB at 1550 nm. The compact footprint (21 × 6 µm2) and CMOS-compatible fabrication further enhance its practical relevance. Experimental results confirm efficient dual-function performance, with low loss and high polarization extinction across a wide bandwidth.

The control of unconventional magnetism, which displays ferromagnetismlike properties with compensated magnetization, has drawn intense attention for advancing antiferromagnetic spintronics. Here, through symmetry analysis, we propose a general stacking rule, characterized by a connection operator linking two stacked bilayers, for controlling unconventional magnetism via sliding ferroelectricity. Such a rule enables the simultaneous switching of both electric polarization and nonrelativistic spin splitting or anomalous Hall effect in altermagnets, a class of collinear unconventional magnets. By comprehensively surveying the 80 layer groups, we identify all the stacking orders that allow for such two types of simultaneous switching. Furthermore, we extend the stacking rule to collinear compensated ferrimagnets, where the opposite-spin sublattices are not connected by any symmetry operator, yet the net magnetization remains zero. Combined with first-principles calculations, we demonstrate the sliding ferroelectric control of spin polarization and anomalous Hall effect in the altermagnetic AgF_{2} and Fe_{2}MoSe_{4} bilayers. Our Letter provides a symmetry strategy for achieving ferroelectric control of unconventional magnetism in bilayer systems and opens avenues for exploring new types of magnetoelectric coupling.