Band 14, Heft 20

Information modulation plays a crucial role in the contemporary development of photonic information networks. However, prevailing optical modulators exhibit challenges such as structural complexity, high cost, elevated insertion losses, and crosstalk issues in optoelectronic conversion. To address these concerns, we propose a novel all-photonic non-volatile fiber device based on Ge 2 Sb 2 Te 5 (GST), integrating a dual peanut-shaped microstructure and GST. The state of GST is manipulated through external laser modulation, enabling repeatable or randomly accessible ten-level data storage. The all-photonic modulator features non-volatility, a contrast ratio of 21 dB, and repeatability (0.2 dB). Furthermore, by configuring the all-photonic modulator in both series and parallel connections, we successfully implement logical gate functions “AND” and “OR”, showcasing significant potential in information network control.

The generation and application of squeezed light have long been central goals of quantum optics. Intensity noise squeezing of bright (coherent) states (“bright squeezing”), in contrast to squeezed vacuum, is relatively underdeveloped. The current state of the art has generally been restricted to narrow operating wavelength ranges and does not natively support strong intracavity and broadband output squeezing. Here, we show how lasers with sharp intensity-dependent dissipation can support strong intensity noise squeezing from infrared (IR) to terahertz (THz) wavelengths, the latter of which has eluded quantum light generation. Our protocol realizes strongly ( > 10 ${ >} 10$ dB) intensity noise-squeezed intracavity quantum states as well as output squeezing surpassing gigahertz bandwidths. Furthermore, we show how the same systems also support self-pulsing and bistability, enabling control of light in both the mean field and noise domains. Our protocol could enable advances in low-noise communication, cavity QED, and quantum sensing across the electromagnetic spectrum.

High-resolution optical imaging in thick tissue samples remains elusive, mainly because of the scattering exhibited by the tissue. With increasing depth, the number of nonscattered photons exponentially decreases – limiting the use of conventional imaging techniques at depth. Wavefront shaping is a novel technique that aims to enable imaging at depth by refocusing the scattered light. However, significant wavefront-control hardware improvements are necessary to unlock the applications in in vivo microscopy. Optical phased arrays (OPAs), realized in integrated photonics, can provide improvements in the pixel pitch, operation speed, and system compactness compared to conventionally employed spatial light modulators. We compare different OPA designs for focusing in tissue-like forward-scattering samples. OPA design trade-offs, such as the array pitch, number of antennas, and antenna emission profile, are experimentally studied, and their influence on the device performance is highlighted. We do this for increasing thickness of the forward-scattering sample and observe two distinct regimes. The devices, operating at the wavelength of λ = 852 nm, were fabricated on a SiN photonics platform suitable for both near-infrared (NIR) and visible (VIS) light.

Bi 2 O 2 Se, with its excellent air stability, high mobility, and tunable bandgap, shows great potential for photonic modulators. This study proposes vacancy engineering as an effective method to refine its optical properties and enhance the nonlinear response. The optical properties of Bi 2 O 2 Se modified by oxygen vacancy defects were systematically investigated through theoretical simulations and experimental methods. Oxygen vacancies enhance photon–material interactions by introducing intermediate energy levels, altering the electronic structure, reducing the bandgap, inducing a redshift in the linear absorption spectrum, and forming a new absorption band near 1 μm. Argon annealing increased the concentration of oxygen vacancies, and the experimental absorption spectra showed excellent agreement with theoretical predictions. To evaluate the impact of oxygen vacancies on the nonlinear optical response, Bi 2 O 2 Se before and after annealing was employed as a saturable absorber in Q-switched and mode-locked lasers. The annealed Bi 2 O 2 Se exhibited a 4.42-fold increase in peak power, a 115.9 fs reduction in pulse width, and a 2.36 nm expansion in 3 dB spectral width. These findings indicate that vacancy engineering is a direct and effective strategy for optimizing the nonlinear optical properties of Bi 2 O 2 Se, which can contribute to advanced photon applications.

The Smith–Purcell effect enables electromagnetic radiation across arbitrary spectral ranges by phase-matching the diffraction orders of an optical grating with the near-field of a moving electron. In this work, we introduce a novel approach using a helically shaped waveguide, where phase-matching is achieved through guided light within a helical optical fiber fabricated via two-photon polymerization using a 3D printer. Our results demonstrate that radiation from these structures precisely satisfies the phase-matching condition and is emitted directionally at specific angles, contrasting with the broad angular distribution characteristic of the traditional Smith–Purcell effect. Helical electron-driven photon sources establish a new paradigm, enabling 3D-printed structures to control electron-beam-induced radiation and, inversely, to facilitate light-induced efficient electron beam shaping and acceleration.

Temporal modulation of material parameters offers unprecedented control over wave dynamics, enabling phenomena beyond the capabilities of static systems. Here we introduce and analyze a robust mechanism for time rewinding, whereby a temporally evolved wave is fully restored to its original state through a carefully engineered sequence of temporal modulations. In electromagnetic systems, time rewinding emerges from impedance-matched or anti-matched hierarchical bilayer structures with matched modulation durations, exploiting total transmission or reflection and reversed phase accumulation. In Dirac systems, it arises via complete interband transition driven by time-dependent vector potentials. Unlike time-reversal holography or quantum time mirrors, which produce wave echoes but only partial waveform recovery, our approach achieves deterministic and complete reconstruction of the entire wave state, including both amplitude and phase. Analytical conditions for robust amplitude and phase restoration are derived and validated through simulations of discrete and continuous modulations, demonstrating resilience to modulation complexity and temporal asymmetry. These findings establish a versatile platform for secure information retrieval, temporal cloaking, programmable metamaterials, and wave-based logic devices.

The intrinsically disordered periodic architecture inherent in natural biomaterials exhibits significant potential for serving as resonant cavities, enabling the development of eco-friendly, biocompatible, and cost-effective microlaser systems. In this study, we demonstrate a biomaterial-based random laser utilizing birch leaf–derived carbon dots (CDs) as the gain medium. CDs ethanol solution was introduced into the peanut via microinjection, successfully fabricating CDs-doped peanut samples that preserved the fluorescence characteristics of the CDs in solution. Random lasing was observed on multiple surfaces of the CDs-doped peanut under pulsed laser excitation, with varying thresholds across different regions. This demonstrates that the natural disordered microstructure of biological materials can facilitate random lasing. Analysis of surface morphology and scattering patterns indicates that the lasing mechanism arises from multiple light scattering within the disordered structure of the peanut surface, forming coherent feedback loops. Furthermore, the intrinsic biocompatibility of bio-derived CDs effectively addresses the persistent toxicity concerns associated with synthetic laser materials. Such biomaterial-based random lasers could enable eco-friendly and cost-effective photonic applications.

Metasurface holograms, characterized by their ultra-small thickness, high efficiency, and low loss, hold significant potential for applications in optical information storage, optical field manipulation, and security encryption. This paper proposed a polarization switchable and rotation multiplexing metasurface based on simultaneous amplitude and phase modulation. By precisely designing meta-atoms, the geometric parameters and orientation angle are engineered to independently control the phase and amplitude distributions of the metasurface. Utilizing a polarization switching strategy, incident light with different polarization angles generates distinct holograms. Additionally, the rotation-multiplexing mechanism further enhances information storage capacity by rotating the metasurface disk, thereby increasing the diversity and degrees of freedom in hologram. The results demonstrate that this approach enables precise optical field manipulation across multiple degrees of freedom, facilitating the reconstruction of multichannel holograms. This method provides a novel technological pathway for high-density optical storage, information encryption, and dynamic optical display.

Wave propagation in time-varying media enables unique control of energy transport by breaking energy conservation through temporal modulation. Among the resulting phenomena, temporal disorder – random fluctuations in material parameters – can suppress propagation and induce localization, analogous to Anderson localization. However, the statistical nature of this process remains incompletely understood. We present a comprehensive analytical and numerical study of electromagnetic wave propagation in spatially uniform media with randomly time-varying permittivity. Using the invariant imbedding method, we derive exact moment equations and identify three distinct statistical regimes for initially unidirectional input: gamma-distributed energy at early times, negative exponential statistics at intermediate times, and a quasi-log-normal distribution at long times, distinct from the true log-normal. In contrast, symmetric bidirectional input yields genuine log-normal statistics across all time scales. These findings are validated using two complementary disorder models – delta-correlated Gaussian noise and piecewise-constant fluctuations – demonstrating that the observed statistics are robust and governed by input symmetry. Momentum conservation constrains the long-time behavior, linking the statistical outcome to the initial conditions. Our results establish a unified framework for understanding statistical wave dynamics in time-modulated systems and offer guiding principles for the design of dynamically tunable photonic and electromagnetic devices.

The ultrathin form factor of metalenses makes them highly appealing for novel sensing and imaging applications. Amongst the various phase profiles, the hyperbolic metalens stands out for being free from spherical aberrations and having one of the highest focusing efficiencies to date. For imaging, however, hyperbolic metalenses present significant off-axis aberrations, severely restricting the achievable field-of-view (FOV). Extending the FOV of hyperbolic metalenses is thus feasible only if these aberrations can be corrected. Here, we demonstrate that a Restormer neural network can be used to correct these severe off-axis aberrations, enabling wide FOV imaging with a hyperbolic metalens camera. Importantly, we demonstrate the feasibility of training the Restormer network purely on simulated datasets of spatially-varying blurred images generated by the eigen-point-spread function (eigenPSF) method, eliminating the need for time-intensive experimental data collection. This reference-free training ensures that Restormer learns solely to correct optical aberrations, resulting in reconstructions that are faithful to the original scene. Using this method, we show that a hyperbolic metalens camera can be used to obtain high-quality imaging over a wide FOV of 54° in experimentally captured scenes under diverse lighting conditions.

Light–matter interactions generally involve momentum exchange between incident photons and the target object giving rise to optical forces and torques. While typically weak, they become significant at the nanoscale, driving intense research interest in the exploitation of photon recoil to drive micro- and nanostructures. While great progress has been attained in controlling transversal degrees of freedom, three-dimensional movement remains challenging, particularly due to the impractical realization of pulling forces that oppose the direction of incident light. Here we theoretically present a novel nanomotor design that enables independent control over both transverse and longitudinal motion. This design exploits coupling between an azimuthally polarized Bessel beam and a dielectric glass cylinder to realistically achieve optical pulling forces. At the same time, asymmetric plasmonic dimers, embedded within the cylinder, provide lateral motion, through asymmetric scattering under plane wave illumination. We further demonstrate that unwanted displacements and rotations can be restrained, even at long illumination times. Our design unlocks a new degree of freedom in motion control, allowing for pulling, pushing, and lateral movement by simply tuning the polarization or switching between plane waves and Bessel beams.