In-Situ Wavefront Correction

In article number 2300833, Xian Long, Jianping Ding, Hui-Tian Wang, and co-workers propose a novel generic calibration scheme based on Zernike-fitting neural networks and a vortex beam focusing model, which enables in-situ wavefront correction with just a single-shot measurement. The proposed method offers fast calibration, a streamlined optical path, and remarkable versatility, making it highly promising for diverse wavefront engineering applications.

Quantum Imaging with Machine Intelligence

In their Review (article number 2300939), Chané Moodley and Andrew Forbes explore the capabilities of the intersection between quantum imaging and artificial intelligence. With technological and AI advancements, we expect faster, higher-quality quantum images. This review explores key progress and future directions in this dynamic and interdisciplinary field.

Electrically-Injected InGaN Microdisk Lasers

High Q, room-temperature lasing in InGaN microdisk lasers under electrical injection is achieved through a thin-film structure enhanced by a metallic undercut, which substantially improves optical confinement and overlap factor. Detailed analysis using near-field optical spectroscopy reveals strain relaxation near the edge plays a crucial role in reducing the Quantum Confined Stark Effect. This improvement in quantum efficiency has significant implications for the enhancement of lasing performance. For more details, see article number 2400047 by Wai Yuen Fu, Yuk Fai Cheung, and Hoi Wai Choi.

Quantum Cascade Surface Emitting Lasers

In article number 2300663, David Stark, Jérôme Faist, and co-workers introduce the Quantum Cascade Surface Emitting Laser (QCSEL, pronounced “kjuxel”), a device concept targeting the mid-infrared equivalent of the Vertical Cavity Surface Emitting Laser (VCSEL). By leveraging miniaturization and wafer-level testing, the authors demonstrate the feasibility of producing low-cost and low-power consuming mid-infrared lasers in high volumes. These devices are proposed for the next generation of compact and portable gas sensing applications involving industrial process control, environmental monitoring, and medical diagnosis.

Quantum imaging exemplifies the fascinating and counter-intuitive nature of the quantum world, where non-local correlations are exploited for the imaging of objects by remote and non-interacting photons. The field has exploded of late, driven by advances in the fundamental understanding of these processes, but also by advances in technology. In this review, a comprehensive overview of the rapidly evolving field of quantum imaging with a specific focus on the intersection of quantum ghost imaging with artificial intelligence and machine learning techniques is provided.

This review focuses on the recent advances in the design and electromagnetic properties of plasmonic nanorod metamaterials, and outlines the fast-developing trends in their exploitation in nanophotonics, ranging from sensing and spontaneous emission engineering to ultrafast nonlinear optics and polarization control.

Principles and latest breakthroughs with nanostructures enabling the extraction of confined light from organic light-emitting diodes (OLEDs) by facilitating strong optical interactions between nanostructures and trapped modes are reviewed. Four types of extraction strategies are examined: periodic nanostructures, randomly distributed nanostructures, metamaterials, and bioinspired nanostructures. Insights of the design parameters of nanostructures are also discussed for optimizing OLED performance.

This study presents an innovative Zernike-fitting neural network (ZFNN) for insitu wavefront correction, requiring just a single measurement without extensive pre-training or data. The proposed method demonstrates rapid calibration, streamlined optical path, and significant versatility has the advantages of fast calibration, simplicity of optical path and excellent versatility, which are confirmed by experimental validation, showing its potential in wavefront engineering applications.

Incorporating a metallic undercut with a thin-film configuration, this research advances InGaN microdisk laser operation under electrical injection, markedly enhancing optical confinement and overlap factor, which contributes to a record high Q factor of 10100. Further analysis indicates strain relaxation near the edge as a key factor in elevating quantum efficiency, with implications for lasing performance enhancement.

In this work, the Quantum Cascade Surface Emitting Laser (QCSEL) is introduced. This mid-infrared laser, producible in high volumes at low cost, leverages wafer-level testing and exploits miniaturization to minimize the electrical power dissipation. The obtained results for wavelengths near 4.5 and 8 µm pave the way to the broad adoption of the QCSEL in optical sensing applications.

This study presents a robust glucose sensing method using deep learning, resilient to sample position variations. Data measured in random sample position using split ring resonator microwave sensors are calibrated by a 1D convolutional neural network.  With an MAE of 0.695% and MSE of 0.876%, the model exhibits superior performance. Transfer learning facilitates fruit Brix estimation, demonstrating practical applicability.

A universal chemical interlinkage-assisted efficient energy transfer (ET) strategy is introduced to achieve color conversion from green to red in traditional persistent mechanoluminescence (PML) materials. The multicolor PML of the RhB@SiO₂/SAOED system remains visible to the naked eye for exceeding 28 s after mechanical stimulation. The RhB@SiO₂/SAOED system demonstrates potential applications ranging from visualized reading activities to multi-mode anticounterfeiting.

Simultaneous Power over Fiber delivery and transmission of 5G New Radio over a single Hollow Core or Multicore Fiber is demonstrated at distances of ten kilometers, yielding promising results compared to Single Mode Fibers. Optically powering a Bluetooth Low Energy load while transmitting 256 QAM data on a 3 GHz RF signal with no degradation is achieved.

A tunable topological optical filter based on integrated Si-LiTaO₃ platform is proposed for ultra-low-power tuning via the Pockels effect of LiTaO₃. The 1D topological filter is capable of linear bidirectional tuning with a wavelength tuning efficiency of 6.64 pm V⁻¹ and a power efficiency of 0.0218 nW pm⁻¹.

Surface acoustic microwave photonic filters are demonstrated on an etchless lithium niobate integrated platform. Microwave filtering is realized by piezoelectric excitation of gigahertz-frequency surface acoustic waves which, by acousto-optically modulating a high-quality photonic microcavity, produce sharp peaks in the microwave spectrum of the output light. A bandwidth of 0.89 MHz is achieved in a fabricated device operating at gigahertz frequencies.

The laser crystallization of titanium dioxide nanotubes is carried out at 151–569 mW and 1–200 mm s⁻¹. Evidence points to a thermal conversion mechanism from amorphous to anatase to rutile phase. Higher scanning speeds lead to higher rutile content and melting, despite lower accumulated fluences. Photocatalytic activity of the laser-crystallized nanotubes is confirmed.

Highly efficient and high-speed triangular micro-size light-emitting/detecting diodes excelling in light output power density (75 W cm⁻²), modulation bandwidth (566 MHz), photo-responsivity (160 mA W⁻¹), and response time (3.1 ns), outperforming traditional circular micro-diodes, are showcased. Outperforming circular counterparts, these diodes also support bidirectional on-chip data transmission through mode switching, boosting emission and detection capabilities.

A two-step sintering method is exploited to achieve highly efficient and thermally stable broadband near-infrared emission in Cr³⁺ activated germanate oxides, and efficient energy transfer from Cr³⁺ to Yb³⁺ is further leveraged to enrich the emission intensity in the shortwave infrared range of 900–1100 nm.

The study proposes azimuthal scanning excitation surface plasmon resonance (SPR) holographic microscopy to obtain SPR intensity and phase images featuring over ten times higher spatial resolution compared with the traditional single excitation method. Benefiting from the high detection sensitivity and spatial resolution, the proposed microscopy shows great potential in nanoparticle analysis, low-dimensional material characterization, and imaging extremely thin or transparent samples.

A novel optical Stern–Gerlach effect is demonstrated in periodically poled electro-optical crystals, whose principal axes rock periodically when an electric field is applied. The electro-optical coupling process within the crystal can be accurately described by the Schrödinge–Pauli equation for spin-1/2 particles. The output photons can be deflected toward opposite directions according to their intrinsic spin angular momentum.

A straightforward strategy to realize compact 2D demultiplexing of orbital angular momentum modes and polarization states by using the versatile all-dielectric metasurfaces is demonstrated in the THz regime. The measured isolation and insertion loss indicate that this few-channel multiplexing strategy holds high promise for integrating into broadband THz communication systems.

The work experimentally demonstrates a ultra-compact, high-speed, and low power consumption electro-optic modulator in the telecommunication wavelength range made of a 1D chain resonator of Mie-resonant silicon nanoparticles. The devices are fabricated at wafer scale by a CMOS compatible process. This modulator shows promise for achieving higher integration density and large modulation bandwidth.

In the course of the high-speed scan writing of voxels in silica glass, a counterintuitive phenomenon of stronger material modification is observed when deposited energy density decreases. This finding, which enables the polarization multiplexed data storage at the MB/s write speed, originates from the nonlocality of light-matter interaction associated with the intensity gradient and diffusion of charge carriers.

Leveraging the spatial coherence of light enhances image resolution in traditional microscopy. A novel formalism demonstrates that the resolution of coherence-based systems is independent of numerical aperture, as confirmed experimentally. This property drives the development of scanning-free multicolor 3D microscopes, validated through histological sample analysis, with full potential for low-cost 3D imaging in real time.

A global design strategy based on field-driven polygon evolution is proposed to achieve the inverse design of large-scale coupled meta-atoms. Through two global simulations, it can effectively reshape any given target optical field into an optimal structural distribution of devices without knowing mapping relationship.

An approach based on intelligent human-like algorithms based on multi-algorithm fusion is proposed for aligning a solid-state ultrafast laser system for the first time. The laser fluorescence and speckle patterns are taken as indications, and the stable mode-locked pulses can be achieved within 40 s from the state of no laser emission.

A novel strategy is proposed for an optically reconfigurable THz polarimetric device based on a phase-change material, which is capable of measuring a wide range of polarization angles with ns switching speed. This concept provides a novel solution to next-generation integrated THz components and systems with polarimetry and control of THz waves for THz applications.

The spatio-temporal coupled-mode theory is proposed for the description of frequency- and space-related nonlinear process in birefringent microrings, which is new and can draw the interests from the birefringent platform photonic integrated circuits. This work has implications for the design and application of monolithic birefringent photonic integrated circuits with high efficiency.

On-chip whispering-gallery-mode (WGM) optical microdisk resonators and a multimode cross-correlation algorithm are proposed and demonstrated on a silicon-on-insulator (SOI) platform. They feature the capabilities to differentiate local sensing targets of interest from global environmental perturbations. A proof-of-concept for nanoparticle detection in variable temperatures is showcased, highlighting advancements in high-sensitivity sensing on integrated photonic platforms.

A reconfigurable subwavelength photorefractive grating (SPG) within a thin-film lithium niobate optical microcavity is demonstrated, benefitting from the photorefractive effect with a short period equal to half of the wavelength of the incident light, without complex fabrication processes. Backward second harmonic generation and vertical excited second harmonic generation are enabled with the assistance of SPGs through quasi-phase-matching.

A space-time information projection all-optical diffractive deep neural network (D²NN) is reported. The network can project the spatial light field distribution into temporal intensity variation, thereby bypassing the detection speed limit of 2D imaging devices and achieving GHz-level operating speed. This design lays the foundation for the development and application of a new generation of high-speed optical neural networks.

Photonic spin-Hall logic devices based on programmable spoof plasmonic metamaterial are reported. The logic rule between “spin” and “coding sequence” determines the propagation behavior of EM waves. “AND,” “NIMPLY,” “OR,” and “NOT” gates have been numerically and experimentally demonstrated. The work offers a powerful and flexible platform for controlling electromagnetic (EM) waves and designing novel logic devices.

In this work, spatial manipulation of the light field in multifunctional metaphotonics has enabled the dynamic deformation of circular Airy beams into Bessel beams via local and global phase mechanism, which facilitates 3D structural transformations of light, showing significant resilience to fabrication defects and marking a breakthrough in non-diffractive beam in nanoscale.

Here, a novel photonic integrated circuit (PIC) measurement method termed the “sweeping optical frequency mixing method (SOHO)”, is introduced. It leverages the principles of optical frequency mixing by incorporating a sweeping laser, a fixed-wavelength laser, and custom control software. It surpasses the traditional PIC measurement methods with real-time operation, 30 dB higher signal-to-noise ratio, and over 100 times better spectral resolution.

Flexible organic crystal waveguides are ideal for creating innovative hierarchical optical circuits. Here, the study presents the fabrication of a hybrid directional coupler using electronically different two pseudo-plastic organic crystals, serving as a key component for an artificial optical neural network system.

Through dual-site synergistic passivation effects, Zn²⁺ enters the lattice as interstitials, and S²⁻ fills the I/Br vacancies, which synergistically improves the perovskite ASE properties. The doped films show a longer fluorescence lifetime and better stability than the pristine perovskite films.

A programmable meta-system with hybrid architecture and superior performance is proposed. The programmable feed array in the meta-system involves doping active elements with passive elements and uses its interconnected configuration to reduce the number of active elements and RF chains significantly. The meta-lens serves as a passive phase shifter to increase the beamforming performance.

The emission of Cr³⁺ is located in NIR-I region under blue light excitation which is suitable for commercial blue LED chips. The emission of Ni²⁺ is located in NIR-II region which cannot be effectually excited by blue light. The co-doping of Cr³⁺ and Ni²⁺ perfectly overcomes this dilemma. By multi-site occupation and effective energy transfer, super broadband emission across NIR-I and NIR-II under blue light excitation is achieved.

Currently, the development of effective strategies for multi-dimensional applications based on lanthanide-doped fluoride NPs is a constant challenge. The NaYF₄:Er³⁺/Mn²⁺@NaLuF₄ core–shell NPs that can be utilized for anti-counterfeiting and high-resolution delayed imaging, which highlights the possibility for multi-dimensional applications are synthesized.

This work introduces a method for generating ultra-high repetition rate pulses, and this method can be used to tune the repetition rate by varying specific parameters in the resonator. It combines the microfiber resonator and the high birefringence fiber into the fiber laser. The repetition rate is up to 3.448 THz, with a tuning range on the order of terahertz.

Integrating polarization-multiplexed metalens with advanced neural network processing, this study introduces a novel computational spectral imaging framework. Through joint optimization of the front-end metalens and the back-end neural network, high fidelity of spectral image recovery is achieved while ensuring miniaturization. This innovation is pivotal for enhancing mobile technology and augmented reality applications.

Orange-emitting single crystals with near-unity quantum yield and excellent moisture resistance in Mn²⁺-alloyed Cs₄Cd_1-xMn_xBi₂Cl₁₂ vacancy-ordered quadruple perovskite are achieved based on the effective [BiCl₆]³⁻→[MnCl₆]⁴⁻ energy transfer and local lattice structure distortion, as well as the formation of a BiOCl protective layer.

Assuming that the rate of variation in the state of polarization (SOP) is much slower than that of phase, the polarization information can be almost independently introduced to the caustic rays of optical fields. For instance, a theoretical expression for non-diffracting vector beams is derived, allowing for free manipulation of both caustic shape and SOP along the caustic curve.