The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light-emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin-film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC-TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain-bandwidth product, and a 100-photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness-optimized SC-TF with much higher mobility and longer recombination time. The results indicate that high-performance perovskite devices based on SC-TF may become competitive in modern optoelectronics.

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Abstract:The resonance phenomena of surface plasmons has enabled development of a novel class of noncontact, real-time and label-free optical sensors, which have emerged as a prominent tool in biochemical sensing and detection. However, various forms of surface plasmon resonances occur with natively strong non-radiative Drude damping that weakens the resonance and limits the sensing performance fundamentally. Here we experimentally demonstrate the first lasing-enhanced surface plasmon resonance (LESPR) refractive index sensor. The figure of merit (FOM) of intensity sensing is~84,000, which is about 400 times higher than state-of-the-art surface plasmon resonance (SPR) sensor. We found that the high FOM originates from three unique features of LESPR sensors: high-quality factor, nearly zero background emission and the Gaussian-shaped lasing spectra. The LESPR sensors may form the basis for a novel class of plasmonic sensors with unprecedented performance for a broad range of applications. Keywords:Surface plasmon resonances, stimulated emission, plasmon lasers, sensors Surface plasmons are quasiparticles of coupled photons and electrons excited at the metal surface [1]. They can be tightly localised at the metal surface and thus highly sensitive to its dielectric environment. Surface plasmon sensors operate on the principle that small changes in refractive index at the vicinity of metal surface can result in a shift of surface plasmon resonance, which can be detected at optical far field, allowing non-contact, realtime and label-free sensing and detection [2][3][4][5][6]. In the past two decades, the surface plasmon resonance (SPR) sensors based on propagating surface plasmon polaritons have become a prominent tool for characterising and quantifying biomolecular interactions and are perhaps the most extensively utilised optical biosensors [3,7,8]. However, the propagating surface plasmons on flat surface cannot be directly excited due to their large momentum. In most SPR sensors, the Kretschmann configuration of attenuated total reflection is used to excite surface plasmons, which requires precise adjustment of the incident angle of the probing radiation [3,7,8]. Therefore, it remains a challenge for SPR sensors to have point-of-care performance and satisfy modern nanobiotechnology architectures [3,7,9].Localised surface plasmons (LSPs) are another type of surface plasmons that have begun to be used in sensors recently [4][5][6]. In contrast to its propagating counterpart, LSPs can be excited directly in metallic structures with dimensions less than half the wavelength. Single metal particle with tunable spectra and enhanced local field can be used for sensing, which is much more suitable for the modern nanobiotechnology architectures [9][10][11][12][13][14][15][16][17][18][19][20]. However, localised surface plasmon resonance (LSPR) sensors are with orders of magnitude lower sensitivity compared with propagating SPR sensors [8,13]. Only when measuring refractive index change in the nanometer vicinity to the meta...

SiQDs with an average diameter of 2.6 ± 0.5 nm are used as the light emitting material in high-efficiency inverted structure light emitting diodes.

Plasmonic nanolasers are a new class of amplifiers that generate coherent light well below the diffraction barrier bringing fundamentally new capabilities to biochemical sensing, super-resolution imaging, and on-chip optical communication. However, a debate about whether metals can enhance the performance of lasers has persisted due to the unavoidable fact that metallic absorption intrinsically scales with field confinement. Here, we report plasmonic nanolasers with extremely low thresholds on the order of 10 kW cm−2 at room temperature, which are comparable to those found in modern laser diodes. More importantly, we find unusual scaling laws allowing plasmonic lasers to be more compact and faster with lower threshold and power consumption than photonic lasers when the cavity size approaches or surpasses the diffraction limit. This clarifies the long-standing debate over the viability of metal confinement and feedback strategies in laser technology and identifies situations where plasmonic lasers can have clear practical advantage.

The precollisional locations and geometries of the Lhasa terrane (LT) are critical to constrain the India‐Asia collision. However, the inclinations of the Cretaceous paleomagnetic data obtained from the northern limb of folds are obviously lower than those obtained from the southern limb, which cause large discrepant paleolatitudes of the LT prior to India‐Asia collision. Here, we carried out a new paleomagnetic investigation on the Late Cretaceous Jingzhushan Formation red beds in the far western LT. The tilt‐corrected site mean direction yielded a palaeopole at 74.4°N, 226.0°E with A95 = 3.8° (N = 54). This paleomagnetic data set passes fold tests and indicates that the studied area was located at 19.6° ± 3.8°N during the Late Cretaceous. However, the mean inclination calculated from the northern limb of folds (Is = 19.0°) is significantly lower than that of the southern limb of folds (Is = 51.8°). This inclination discrepancy of the Jingzhushan Formation red beds may be attributed to the syntectonic sedimentation. Nevertheless, the site mean direction obtained from both limbs of folds is generally consistent with the site mean direction after syntectonic‐sedimentation correction. Our new paleomagnetic results, combined with the reliable Cretaceous paleomagnetic results from the LT showed that the southern margin of Asia had a present‐day relatively east‐west alignment prior to India‐Asia collision.

Plasmonic nanolasers with strong field confinement beyond the diffraction limit are an emergent tool for various applications, ranging from on-chip optical interconnectors to biomedical sensing and imaging. However, despite the rapidly advanced research in plasmonic nanolasers, there is no study on their stability and yield yet. Here, we systematically study the stability and yield of plasmonic nanolasers and reveal that surface passivation is crucial for them to operate in biocompatible aqueous solution with high stability and yield. We further demonstrate passivated plasmonic nanolasers as refractive index sensors. The figure of merit of intensity sensing is ∼8000, which is about 40 times higher than a state-of-the-art surface plasmon resonance sensor. Our results hold promise for practical applications of plasmonic nanolasers in super-resolution imaging, ultrasensitive sensing, and detection.