Light-Science & Applications最新文献

Perovskite quantum dots (PQDs) show promise in light-emitting diodes (LEDs). However, near-infrared (NIR) LEDs employing PQDs exhibit inferior external quantum efficiency related to the PQD emitting in the visible range. One fundamental issue arises from the PQDs dynamic surface: the ligand loss and ions migration to the interfacial sites serve as quenching centers, resulting in trap-assisted recombination and carrier loss. In this work, we developed a chemical treatment strategy to eliminate the interface quenching sites and achieve high carrier utilization. We employ a bidentate and liquid agent (Formamidine thiocyanate, FASCN) with tight binding to suppress the ligand loss and the formation of interfacial quenching sites: the FASCN-treated films exhibit fourfold higher binding energy than the original oleate ligands. Furthermore, the short ligands (carbon chain <3) enable the treated films to show eightfold higher conductivity; and the liquid characteristics of FASCN avoid the use of high polar solvents and guarantee better passivation. The high conductivity ensures efficient charge transportation, enabling PQD-based NIR-LEDs to have a record-low voltage of 1.6 V at 776 nm. Furthermore, the champion EQE of the treated LEDs is ~23%: this is twofold higher than the control, and represents the highest among reported PQD-based NIR-LEDs.

Colloidal quantum dots (CQDs) are attractive gain media due to their wavelength-tunability and low optical gain threshold. Consequently, CQD lasers, especially the surface-emitting ones, are promising candidates for display, sensing and communication. However, it remains challenging to achieve a low-threshold surface-emitting CQD laser array with high stability and integration density. For this purpose, it is necessary to combine the improvement of CQD material and laser cavity. Here, we have developed high-quality CQD material with core/interlayer/graded shell structure to achieve a low gain threshold and high stability. Subsequently, surface-emitting lasers based on CQD-integrated circular Bragg resonator (CBR) have been achieved, wherein the near-unity mode confinement factor (Γ of 89%) and high Purcell factor of 22.7 attributed to the strong field confinement of CBR enable a low lasing threshold of 17 μJ cm⁻², which is 70% lower than that (56 μJ cm⁻²) of CQD vertical-cavity surface-emitting laser. Benefiting from the high quality of CQD material and laser cavity, the CQD CBR laser is capable of continuous stable operation for 1000 hours (corresponding to 3.63 × 10⁸ pulses) at room temperature. This performance is the best among solution-processed lasers composed of nanocrystals. Moreover, the miniaturized mode volume in CBR allows the integration of CQD lasers with an unprecedentedly high density above 2100 pixels per inch. Overall, the proposed low-threshold, stable and compactly integrated CQD CBR laser array would advance the development of CQD laser for practical applications.

Correction to: Light: Science & Applications https://doi.org/10.1038/s41377-024-01557-4, published online 02 September 2024

Current trends in artificial intelligence toward larger models demand a rethinking of both hardware and algorithms. Photonics-based systems offer high-speed, energy-efficient computing units, provided algorithms are designed to exploit photonics’ unique strengths. The recent implementation of cellular automata in photonics demonstrates how a few local interactions can achieve high throughput and precision.

The burgeoning volume of parameters in artificial neural network models has posed substantial challenges to conventional tensor computing hardware. Benefiting from the available optical multidimensional information entropy, optical intelligent computing is used as an alternative solution to address the emerging challenges of electrical computing. These limitations, in terms of device size and photonic integration scale, have hindered the performance of optical chips. Herein, an ultrahigh computing density optical tensor processing unit (OTPU), which is grounded in an individual microring resonator (MRR), is introduced to respond to these challenges. Through the independent tuning of multiwavelength lasers, the operational capabilities of an MRR are orchestrated, culminating in the formation of an optical tensor core. This design facilitates the execution of tensor convolution operations via the lightwave and microwave multidomain hybrid multiplexing in terms of the time, wavelength, and frequency of microwaves. The experimental results for the MRR-based OTPU show an extraordinary computing density of 34.04 TOPS/mm². Additionally, the achieved accuracy rate in recognizing MNIST handwritten digits was 96.41%. These outcomes signify a significant advancement toward the realization of high-performance optical tensor processing chips.

Achiral dielectric nanostructures provide an efficient method for discriminating left- and right-circularly polarized photons, leveraging the photothermoelectric effect.

This item from the News and Views (N&V) category aims to provide a summary of theoretical and experimental results recently published in ref. ²⁴, which demonstrates the creation of corner modes in nonlinear optical waveguides of the higher-order topological insulator (HOTI) type. Actually, these are second-order HOTIs, in which the transverse dimension of the topologically protected edge modes is smaller than the bulk dimension (it is 2, in the case of optical waveguide) by 2, implying zero dimension of the protected modes, which are actually realized as corner or defect ones. Work²⁴ reports the prediction and creation of various forms of the corner modes in a HOTI with a fractal transverse structure, represented by the Sierpiński gasket (SG). The self-focusing nonlinearity of the waveguide's material transforms the corner modes into corner solitons, almost all of which are stable. The solitons may be attached to external or internal corners created by the underlying SG. This N&V item offers an overview of these new findings reported in ref. ²⁴ and other recent works, and a brief discussion of directions for further work on this topic.

Multicolor microscopy and super-resolution optical microscopy are two widely used techniques that greatly enhance the ability to distinguish and resolve structures in cellular imaging. These methods have individually transformed cellular imaging by allowing detailed visualization of cellular and subcellular structures, as well as organelle interactions. However, integrating multicolor and super-resolution microscopy into a single method remains challenging due to issues like spectral overlap, crosstalk, photobleaching, phototoxicity, and technical complexity. These challenges arise from the conflicting requirements of using different fluorophores for multicolor labeling and fluorophores with specific properties for super-resolution imaging. We propose a novel multicolor super-resolution imaging method called phasor-based fluorescence spatiotemporal modulation (Phasor-FSTM). This method uses time-resolved detection to acquire spatiotemporal data from encoded photons, employs phasor analysis to simultaneously separate multiple components, and applies fluorescence modulation to create super-resolution images. Phasor-FSTM enables the identification of multiple structural components with greater spatial accuracy on an enhanced laser scanning confocal microscope using a single-wavelength laser. To demonstrate the capabilities of Phasor-FSTM, we performed two-color to four-color super-resolution imaging at a resolution of ~λ/5 and observed the interactions of organelles in live cells during continuous imaging for a duration of over 20 min. Our method stands out for its simplicity and adaptability, seamlessly fitting into existing laser scanning microscopes without requiring multiple laser lines for excitation, which also provides a new avenue for other super-resolution imaging technologies based on different principles to build multi-color imaging systems with the requirement of a lower budget.

Randomness is an essential resource and plays important roles in various applications ranging from cryptography to simulation of complex systems. Certified randomness from quantum process is ensured to have the element of privacy but usually relies on the device’s behavior. To certify randomness without the characterization for device, it is crucial to realize the one-sided device-independent random number generation based on quantum steering, which guarantees security of randomness and relaxes the demands of one party’s device. Here, we distribute quantum steering between two distant users through a 2 km fiber channel and generate quantum random numbers at the remote station with untrustworthy device. We certify the steering-based randomness by reconstructing covariance matrix of the Gaussian entangled state shared between distant parties. Then, the quantum random numbers with a generation rate of 7.06 Mbits/s are extracted from the measured amplitude quadrature fluctuation of the state owned by the remote party. Our results demonstrate the first realization of steering-based random numbers extraction in a practical fiber channel, which paves the way to the quantum random numbers generation in asymmetric networks.

Topology is usually perceived intrinsically immutable for a given object. We argue that optical topologies do not immediately enjoy such benefits. Using ‘optical skyrmions’ as an example, we show that they will exhibit varying textures and topological invariants (skyrmion numbers), depending on how to construct the skyrmion vector when projecting from real to parameter space. We demonstrate the fragility of optical skyrmions under a ubiquitous scenario--simple reflection off an optical mirror. Optical topology is not without benefit, but it must not be assumed.