Light, science & applications最新文献

Current crystalline thin-film production techniques typically require specific growth substrates, posing significant challenges for their use in flexible electronics and integrated optoelectronics. In response to these challenges, we introduce a novel method called 'induced fit growth', inspired by the induced fit theory in molecular biology. This method overcomes the limitations of current techniques by enabling the deposition of Ga-based semiconductor films, including GaSb, GaSe, GaAs, and GaAsSb, with controllable thickness and morphology on arbitrary substrates. Utilizing a low-cost, wafer-scale vapor deposition process compatible with standard semiconductor procedures, these Ga-based films can be patterned for various functional applications. For example, the patterned Ga-based thin films exhibit broad applicability in p-channel transistor arrays (with hole mobility of 0.25 cm² V⁻¹ s⁻¹), functional synaptic devices, and flexible omnidirectional imaging sensors (maintaining functionality at incident angles as low as 5°). Overall, the proposed induced fit growth method facilitates the growth of Ga-based semiconductor films with greater integration flexibility, enhancing their advanced functionality and broad applicability.

Micro-nano lasers hold significant promise for on-chip integrated photonics, where perovskite materials emerge as compelling gain media despite stability challenges. While moisture typically degrades perovskite structures, its controlled integration can paradoxically enhance crystallization. Here, we demonstrate a synergistic strategy utilizing water molecules and butylated hydroxytoluene (BHT) additive to achieve high-quality methylammonium lead iodide (MAPbI₃) films with low defect density. Through optimized BHT (4 wt%) combined with 95% relative humidity treatment, we attain an unprecedented amplified spontaneous emission (ASE) threshold of 8.987 μJ cm⁻² under nanosecond pulse excitation - the lowest value reported to date. This dual-triggered film completes ASE intensity retention after 30-day ambient storage. In situ structural and optoelectronic characterization reveals that BHT extends water-perovskite interaction, facilitating organic cation vertical diffusion and preferential (110)-oriented crystallization with 53.02% perpendicular alignment. Transient absorption (TA) spectroscopy confirms suppressed non-radiative recombination, evidenced by 11% prolonged carrier lifetime (6145 ps), while temperature-dependent photoluminescence reveals enhanced exciton binding energy (73.50 meV vs. 60.68 meV) conducive to low-threshold lasing. This work transforms moisture from a degradation agent into a crystallization promoter, establishing a paradigm for high-performance perovskite lasers with simultaneous efficiency and stability.

Spontaneously emitted photons are entangled with the electronic and nuclear degrees of freedom of the emitting atom, so interference and measurement of these photons can entangle separate matter-based quantum systems as a resource for quantum information processing. Since confinement in a single-mode facilitates the photon interference needed for generating entanglement, the dipole emission patterns relevant in spontaneous emission present a mode-matching challenge. Current demonstrations rely on bulk photon-collection and manipulation optics that suffer from large component size and system-to-system variability-factors that impede scaling to the large numbers of entangled pairs needed for quantum information processing. To address these limitations, we demonstrate a collection method that enables passive phase stability, straightforward photonic manipulation, and intrinsic reproducibility. Specifically, we engineer a waveguide-integrated grating to couple photons emitted from a trapped ion into a single optical mode within a microfabricated ion-trap chip. Using the integrated collection optic, we characterize the collection efficiency, image the ion, and detect the ion's quantum state. The integrated optic covers 2.18% of the solid angle and collects 1.97 ± 0.3% of the spontaneously emitted light incident on the grating for a total collection efficiency of 0.043% into a single-mode waveguide. This proof-of-principle demonstration lays the foundation for leveraging the inherent stability and reproducibility of integrated photonics to create, manipulate, and measure multipartite quantum states in arrays of quantum emitters.

Detecting concealed chemicals and explosives remains a critical challenge in global security. Terahertz time-domain spectroscopy (THz-TDS) offers a promising non-invasive and stand-off detection technique owing to its ability to penetrate optically opaque materials without causing ionization damage. While many chemicals exhibit distinct spectral features in the terahertz range, conventional terahertz-based detection methods often struggle in real-world environments, where variations in sample geometry, thickness, and packaging can lead to inconsistent spectral responses. In this study, we present a chemical imaging system that integrates THz-TDS with deep learning to enable accurate pixel-level identification and classification of different explosives. Operating in reflection mode and enhanced with plasmonic nanoantenna arrays, our THz-TDS system achieves a peak dynamic range of 96 dB and a detection bandwidth of 4.5 THz, supporting practical, stand-off operation. By analyzing individual time-domain pulses with deep neural networks, the system exhibits strong resilience to environmental variations and sample inconsistencies. Blind testing across eight chemicals-including pharmaceutical excipients and explosive compounds-resulted in an average classification accuracy of 99.42% at the pixel level. Notably, the system maintained an average accuracy of 88.83% when detecting explosives concealed under opaque paper coverings, demonstrating its robust generalization capability. These results highlight the potential of combining advanced terahertz spectroscopy with neural networks for highly sensitive and specific chemical and explosive detection in diverse and operationally relevant scenarios.

High-harmonic generation (HHG) is used as a source for various imaging applications in the extreme ultraviolet spectral range. It offers spatially coherent radiation and unique elemental contrast with the potential for attosecond time resolution. The unfavorable efficiency scaling to higher photon energies prevented the imaging application in the soft X-ray range so far. In this work we demonstrate the feasibility of using harmonics for imaging in the water window spectral region (284 eV to 532 eV). We achieve nondestructive depth profile imaging in a heterostructure by utilizing a broadband and noise-resistant technique called soft X-ray Coherence Tomography (SXCT) at a high-flux lab-scale HHG source. SXCT is derived from Optical Coherence Tomography, a Fourier based technique that can use the full bandwidth of the source to reach an axial resolution of 12 nm in this demonstration. The employed source covers the entire water window, with a photon flux exceeding 10⁶ photons/eV/s at a photon energy of 500 eV. We show local cross sections of a sample consisting of Aluminium oxide and Platinum layers of varying thickness on a Zinc oxide substrate. We validate the findings with scanning and transmission electron microscopy after preparation with focused ion beam milling.

Solution-processed Sn-Pb perovskites have emerged as promising candidates for near-infrared (NIR) photodetectors due to their low-cost, tunable bandgap and scalable fabrication. However, Sn²⁺ oxidation creates Sn vacancies and undesirable p-type doping, resulting in high dark current and limited detectivity, which hinder the practical deployment of Sn-Pb perovskite photodetectors. Herein, we propose a Sn(SCN)₂ inorganic molecular surface passivation strategy to suppress Sn²⁺ oxidation, significantly reduce surface defect density and enhance the optoelectronic properties (a dark current density of 10 nA cm^-2 at a bias of -0.1 V and a high specific detectivity of ~1.6 × 10¹³ Jones). Leveraging this approach, we report the monolithically integrated Sn-Pb perovskite NIR imager with a complementary metal-oxide-semiconductor readout circuit. The imager, featuring a 640 × 512 pixel array with a 15 μm pixel pitch, achieves an external quantum efficiency of 76% at 940 nm and a modulation transfer function of 206.5 LW/PH at 50%. Furthermore, the Sn-Pb perovskite imager demonstrates advanced material recognition capabilities, including liquid identification, underscoring its potential in chemical sensing, biomedical imaging and industrial inspection.

An intense ultrafast pulse white laser with continuous and ultraflat spectral coverage from deep-ultraviolet (DUV) to far-infrared (FIR) can open up a new arena of full-spectrum laser spectroscopy with applications to a wide variety of basic science and technology areas. Here, we present the creation of an intense white laser with 200-25,000 nm bandwidth @17 dB and ~1 mJ pulse energy by exploiting the synergic action of a high-efficiency nonlinear up-conversion module and down-conversion module upon an intense mid-infrared (MIR) seed pulse laser. The MIR seed pulse laser of 3.62 mJ pulse energy is achieved by sending an optical-parametric chirped pulse amplification pulse laser of 7.12 mJ pulse energy and 3.9 µm central wavelength through a krypton gas-filled hollow-core fiber. The up-conversion nonlinear module is a deliberately designed chirped-periodic poling lithium niobate (CPPLN) nonlinear crystal supporting simultaneous broadband second-order nonlinear 2nd-12th harmonic generation upon the seed laser to generate the shortest DUV wavelength down to 200 nm with a nearly 40% conversion efficiency. The down-conversion nonlinear module is composed of a bare LN crystal offering third-order nonlinear spectral broadening effect and a cascaded AgGaSe₂ nonlinear crystal offering high-efficiency intra-pulse difference-frequency generation, and generates a 2000-25,000 nm MIR-FIR laser with an overall conversion efficiency of 18%. The intense 7-octave ultraflat DUV-FIR white laser would offer an unprecedented power to simultaneously probe and monitor the electronic transition, molecular vibration, and lattice oscillation in a wide variety of physical, chemical, and biological substances and processes.

Quantitative phase imaging (QPI) provides valuable objective insights for investigating transparent samples, yet miniaturizing QPI systems without compromising performance remains a critical challenge for applications requiring compactness and portability. Here, by introducing partially coherent illumination modulation, together with a plan meta-objective (PMO) design, we present a compact QPI system with sub-micron resolution. The PMO is a monolithically integrated doublet metalens with its dispersion enabling focal shifts at two wavelengths, obviating the need for mechanical translations during image acquisition for phase retrieval. The PMO is also optimized to correct for monochromatic aberrations, delivering an object-side field of view equivalent to ~90% of the lens aperture with minimal distortion and aberrations. The spatial coherence of the illumination is controlled to enhance imaging resolution. By co-designing illumination and imaging systems, we demonstrate QPI achieving a half-pitch lateral resolution of 488 nm with a phase accuracy of 0.06λ. Our approach enables high-quality QPI analysis of diverse phase objects, including unstained biospecimens, laying the foundation for the development of compact, stable, and practical QPI platforms.

Coherent Ising machines (CIMs) have emerged as a hybrid form of quantum computing devices designed to solve NP-complete problems, offering an exciting opportunity for discovering optimal solutions. Despite challenges such as susceptibility to noise-induced local minima, we achieved notable advantages in improving the computational accuracy and stability of CIMs. We conducted a successful experimental demonstration of CIM via femtosecond laser pumping that integrates optimization strategies across optical and structural dimensions, resulting in significant performance enhancements. The results are particularly promising. An average success rate of 55% was achieved to identify optimal solutions within a Möbius Ladder graph comprising 100 vertices. Compared with other alternatives, the femtosecond pulse results in significantly higher peak power, leading to more pronounced quantum effects and lower pump power in optical fiber-based CIMs. In addition, we have maintained an impressive success rate for a continuous period of 8 hours, emphasizing the practical applicability of CIMs in real-world scenarios. Furthermore, our research extends to the application of these principles in practical applications such as molecular docking and credit scoring. The results presented substantiate the theoretical promise of CIMs, paving the way for their integration into large-scale practical applications.

Mid-infrared semiconductor lasers operating in the 2.0-5.0 μm spectral range play an important role for various applications, including trace-gas detection, biomedical analysis, and free-space optical communication. InP-based quantum-well (QW) and quantum-dash (Qdash) lasers are promising alternatives to conventional GaSb-based QW lasers because of their lower cost and mature fabrication infrastructure. However, they suffer from high threshold current density (J_th) and limited operation temperatures. InAs/InP quantum-dot (QD) lasers theoretically offer lower J_th owing to their three-dimensional carrier confinement. Nevertheless, achieving high-density, uniform InAs/InP QDs with sufficient gain for lasing over 2 μm remains a major challenge. Here, we report the first demonstration of mid-infrared InAs/InP QD lasers emitting beyond 2 μm. Five-stack InAs/In_0.532Ga_0.468As/InP QDs grown by molecular-beam epitaxy exhibit room-temperature photoluminescence at 2.04 μm. Edge-emitting lasers achieve lasing at 2.018 μm with a low J_th of 589 A cm^-2 and a maximum operation temperature of 50 °C. Notably, the J_th per layer (118 A cm^-2) is the lowest ever reported for room-temperature InP-based mid-infrared lasers, outperforming QW/Qdash counterparts. These results pave the way for a new class of low-cost, high-performance mid-infrared light sources using InAs/InP QDs, marking a notable step forward in the development of mid-infrared semiconductor lasers.