Light-Science & Applications最新文献

Non-reciprocal optical components are indispensable in optical applications, and their realization without any magnetic field has attracted increasing research interest in photonics. Exciting experimental progress has been achieved by either introducing spatial-temporal modulation of the optical medium or combining Kerr-type optical nonlinearity with spatial asymmetry in photonic structures. However, extra driving fields are required for the first approach, while the isolation of noise and the transmission of the signal cannot be simultaneously achieved for the other approach. Here, we propose the mechanism of nonlinear non-reciprocal susceptibility for optical media and experimentally realize the self-induced isolation of optical signals without any external bias field. The self-induced isolation by the input signal is demonstrated with an extremely high isolation ratio of 63.4 dB, a bandwidth of 2.1 GHz for 60 dB isolation, and a low insertion loss of ~1 dB. Furthermore, the new mechanism allows novel functional optical devices, including polarization purification and non-reciprocal leverage. A complete passive isolator is realized by introducing an asymmetry cavity. It is demonstrated that the 70 μW signal could lever the non-reciprocity and realize a 30 dB isolation of the backward laser with a power 100 times higher. The demonstrated nonlinear non-reciprocal medium provides a versatile tool to control light and deepen our understanding of light-matter interactions and enables applications ranging from topological photonics to unidirectional quantum information transfer in a network.

Low-dimensional lead-free metal halide perovskites are highly attractive for cutting-edge optoelectronic applications. Herein, we report a class of scandium-based double perovskite crystals comprising antimony dopants that can generate multiexcitonic emissions in the ultraviolet, blue, and yellow spectral regions. Owing to the zero-dimensional nature of the crystal lattice that minimizes energy crosstalk, different excitonic states in the crystals can be selectively excited by ultraviolet light, X-ray irradiation, and mechanical action, enabling dynamic control of steady/transient-state spectral features by modulating the excitation modes. Remarkably, the transparent crystal exhibits highly efficient white photoluminescence (quantum yield >97%), X-ray excited blue emission with long afterglow (duration >9 h), and high-brightness self-reproducible violet-blue mechanoluminescence. These findings reveal the exceptional capability of low-dimensional perovskite crystals for integrating various excitonic luminescence, offering exciting opportunities for multi-level data encryption and all-in-one authentication technologies.

Continuous-wave mode-locking at multi-GHz repetition rates is achieved in an ultrashort laser cavity at critical pulse energies 100 times lower than predicted by conventional theory. The authors reveal that dynamic gain depletion and recovery between consecutive round-trips is the key factor behind a low-pulse-energy transition from Q-switched mode-locking (QSML) to continuous-wave mode-locking (CWML). As well as providing new insight into gain dynamics, the results suggest a practical route to low-threshold lasing at very high-repetition rates.

Wide field of view and light weight optics are critical for advanced eyewear, with applications in augmented/virtual reality and night vision. Conventional refractive lenses are often stacked to correct aberrations at a wide field of view, leading to limited performance and increased size and weight. In particular, simultaneously achieving a wide field of view and large aperture for light collection is desirable but challenging to realize in a compact form-factor. Here, we demonstrate a wide field of view (greater than 60^∘) meta-optic doublet eyepiece with an entrance aperture of 2.1 cm. At the design wavelength of 633 nm, the meta-optic doublet achieves comparable performance to a refractive lens-based eyepiece system. This meta-doublet eyepiece illustrates the potential for meta-optics to play an important role in the development of high-quality monochrome near-eye displays and night vision systems.

Oxide materials with a non-centrosymmetric structure exhibit bulk photovoltaic effect (BPVE) but with a low cell efficiency. Over the past few years, relatively larger BPVE coefficients have been reported for two-dimensional (2D) layers and stacks with asymmety-induced spontaneous polarization. Here, we report a crucial breakthrough in boosting the BPVE in 3R-MoS₂ by adopting edge contact (EC) geometry using bismuth semimetal electrode. In clear contrast to the typically used top contact (TC) geometry, the EC metal which strongly adheres to the edges and the subtrates can induce a pronounced tensile strain to the 3R-MoS₂, and the lateral contact geometry allows to completely access to in-plane polarization from underneath layers reachable by light, leading to >100 times of BPVE enhancement in photocurrent. We further design a 3R-MoS₂/WSe₂ heterojunction to demonstrate constructive coupling of BPVE with the conventional photovoltaic effect, indicating their potential in photodetectors and photovoltaic devices.

Visible light microlasers are essential building blocks for integrated photonics. However, achieving low-threshold (μW), continuous-wave (CW) visible light lasing at room temperature (RT) has been a challenge because of the formidable requirement of population inversion at short wavelengths. Rare-earth (RE)-activated microcavities, featuring high-quality factor (Q) and small mode volume of whispering gallery modes, offer a great opportunity for achieving infrared-to-visible upconversion (UC) lasing. Here, we report that batch-produced nano-glass composite (GC) microspheres incorporating RE-doped fluoride nanocrystals show efficient UC emissions. These multi-phase composite microspheres exhibit a high Q value (≥10⁵), comparable to that of conventional multi-component glass microspheres. The UC lasing with pure red, green, and blue (RGB) emissions are demonstrated based on a highly efficient tapered fiber-microsphere system. More importantly, the GC microspheres manifest reduced (by 45%) lasing threshold and enhanced (more than four times) slope efficiency. These characteristics, together with excellent long-term stability, suggest a promising solution to achieving highly robust, stand-alone, low-threshold, and versatile UC microlasers.

High-power tunable lasers are intensely pursued due to their vast application potential such as in telecom, ranging, and molecular sensing. Integrated photonics, however, is usually considered not suitable for high-power applications mainly due to its small size which limits the energy storage capacity and, therefore, the output power. In the late 90s, to improve the beam quality and increase the stored energy, large-mode-area (LMA) fibers were introduced in which the optical mode area is substantially large. Such LMA fibers have transformed the high-power capability of fiber systems ever since. Introducing such an LMA technology at the chip-scale can play an equally disruptive role with high power signal generation from an integrated photonics system. To this end, in this work we demonstrate such a technology, and show a very high-power tunable laser with the help of a silicon photonics based LMA power amplifier. We show output power reaching 1.8 W over a tunability range of 60 nm, spanning from 1.83 µm to 1.89 µm, limited only by the seed laser. Such an integrated LMA device can be used to substantially increase the power of the existing integrated tunable lasers currently limited to a few tens of milliwatts. The power levels demonstrated here reach and surpass that of many benchtop systems which truly makes the silicon photonics based integrated LMA device poised towards mass deployment for high power applications without relying on benchtop systems.

We introduce a family of membrane-targeted azobenzenes (MTs) with a push-pull character as a new tool for cell stimulation. These molecules are water soluble and spontaneously partition in the cell membrane. Upon light irradiation, they isomerize from trans to cis, changing the local charge distribution and thus stimulating the cell response. Specifically, MTs photoisomerization induces clear and reproducible depolarization. The most promising species, MTP2, was extensively studied. Time-resolved spectroscopy techniques provide insights into the excited state evolution and a complete understanding of its isomerization reaction. Molecular Dynamics simulations reveal the spontaneous and stable partitioning of the compound into the cellular membrane, without significant alterations to the bilayer thickness. MTP2 was tested in different cell types, including HEK293T cells, primary neurons, and cardiomyocytes, and a steady depolarization is always recorded. The observed membrane potential modulation in in-vitro models is attributed to the variation in membrane surface charge, resulting from the light-driven modulation of the MT dipole moment within the cell membrane. Additionally, a developed mathematical model successfully captures the temporal evolution of the membrane potential upon photostimulation. Despite being insufficient for triggering action potentials, the rapid light-induced depolarization holds potential applications, particularly in cardiac electrophysiology. Low-intensity optical stimulation with these modulators could influence cardiac electrical activity, demonstrating potential efficacy in destabilizing and terminating cardiac arrhythmias. We anticipate the MTs approach to find applications in neuroscience, biomedicine, and biophotonics, providing a tool for modulating cell physiology without genetic interventions.

A novel monocular depth-sensing camera based on meta-imaging sensor technology has been developed, offering more precise depth sensing with millimeter-level accuracy and enhanced robustness compared to conventional 2D and light-field cameras.

Even though efficient near-infrared (NIR) detection is critical for numerous applications, state-of-the-art NIR detectors either suffer from limited capability of detecting incoming photons, i.e., have poor spectral responsivity, or are made of expensive group III-V non-CMOS compatible materials. Here we present a nanoengineered PIN-photodiode made of CMOS-compatible germanium (Ge) that achieves a verified external quantum efficiency (EQE) above 90% over a wide wavelength range (1.2–1.6 µm) at zero bias voltage at room temperature. For instance, at 1.55 µm, this corresponds to a responsivity of 1.15 A/W. In addition to the excellent spectral responsivity at NIR, the performance at visible and ultraviolet wavelengths remains high (EQE exceeds even 100% below 300 nm) resulting in an exceptionally wide spectral response range. The high performance is achieved by minimizing optical losses using surface nanostructures and electrical losses using both conformal atomic-layer-deposited aluminum oxide surface passivation and dielectric induced electric field -based carrier collection instead of conventional pn-junction. The dark current density of 76 µA/cm² measured at a reverse bias of 5 V is lower than previously reported for Ge photodiodes. The presented results should have an immediate impact on the design and manufacturing of Ge photodiodes and NIR detection in general.