Recent advances in nonlinear optics have revolutionized integrated photonics, providing on-chip solutions to a wide range of new applications. Currently, state of the art integrated nonlinear ...photonic devices are mainly based on dielectric material platforms, such as Si
N
and SiO
. While semiconductor materials feature much higher nonlinear coefficients and convenience in active integration, they have suffered from high waveguide losses that prevent the realization of efficient nonlinear processes on-chip. Here, we challenge this status quo and demonstrate a low loss AlGaAs-on-insulator platform with anomalous dispersion and quality (Q) factors beyond 1.5 × 10
. Such a high quality factor, combined with high nonlinear coefficient and small mode volume, enabled us to demonstrate a Kerr frequency comb threshold of only ∼36 µW in a resonator with a 1 THz free spectral range, ∼100 times lower compared to that in previous semiconductor platforms. Moreover, combs with broad spans (>250 nm) have been generated with a pump power of ∼300 µW, which is lower than the threshold power of state-of the-art dielectric micro combs. A soliton-step transition has also been observed for the first time in an AlGaAs resonator.
The ability to spectrally translate lightwave signals in a compact, low-power platform is at the heart of the promise of nonlinear nanophotonic technologies. For example, a device to connect the ...telecommunications band with visible and short near-infrared wavelengths can enable a connection between high-performance chip-integrated lasers based on scalable nanofabrication technology with atomic systems used for time and frequency metrology. Although second-order nonlinear (χ(2)) systems are the natural approach for bridging such large spectral gaps, here we show that third-order nonlinear (χ(3)) systems, despite their typically much weaker nonlinear response, can realize spectral translation with unprecedented performance. By combining resonant enhancement with nanophotonic mode engineering in a silicon nitride microring resonator, we demonstrate efficient spectral translation of a continuous-wave signal from the telecom band (~1,550 nm) to the visible band (~650 nm) through cavity-enhanced four-wave mixing. We achieve such translation over a wide spectral range >250 THz with a translation efficiency of (30.1 ± 2.8)% and using an ultralow pump power of (329 ± 13) μW. The translation efficiency projects to (274 ± 28)% at 1 mW and is more than an order of magnitude larger than what has been achieved in current nanophotonic devices.
In 6 to 10% of patients with acute myeloid leukemia, mutant isocitrate dehydrogenase 1 is thought to contribute to leukemogenesis. Ivosidenib is an oral inhibitor of mutant IDH1. In a randomized ...trial, event-free survival was significantly longer with ivosidenib and azacitidine than with placebo and azacitidine.
In order to solve the social phenomenon of difficult employment of college students, this paper constructs a college employment recommendation platform based on an improved collaborative filtering ...algorithm. Firstly, the framework of the employment recommendation system is designed for the user use case, system architecture, system function module, database and user portrait of the platform, respectively. The functional modules are divided into six module parts: campus recruitment management, internship management, employment information management, employment affairs management, employment analysis management, and employment guidance management. Next, the platform is analyzed to combine the recommendation algorithm of collaborative filtering algorithm and clustering technology based on users and items to realize the recommendation of employment information for college students. Then the employment platform is used to get the high stickiness of users in the employment of college students, which can retain about 62% of the number of people, and even 5% of the number of people are particularly fond of the platform. With the increase in recommendation times, the recommendation accuracy increased from 22% to 83%, and the accuracy increased by about 61%, and the comparison with the traditional employment form is much higher than the traditional method in both accuracy and recall rate by about 30%. It is concluded that using the college employment recommendation platform can realize the precise employment of college students.
Nonlinearity is a powerful determinant of physical systems. Controlling nonlinearity leads to interesting states of matter and new applications. In optics, diverse families of continuous and discrete ...states arise from balance of nonlinearity and group-velocity dispersion (GVD). Moreover, the dichotomy of states with locally enhanced or diminished field intensity depends critically on the relative sign of nonlinearity and either anomalous or normal GVD. Here, we introduce a resonator with unconditionally normal GVD and a single defect mode that supports both dark, reduced-intensity states and bright, enhanced-intensity states. We access and explore this dark-to-bright pulse continuum by phase-matching with a photonic-crystal resonator, which mediates the competition of nonlinearity and normal GVD. These stationary temporal states are coherent frequency combs, featuring highly designable spectra and ultralow noise repetition-frequency and intensity characteristics. The dark-to-bright continuum illuminates physical roles of Kerr nonlinearity, GVD, and laser propagation in a gapped nanophotonic medium.
Type-II nodal line semimetal He, Jing; Kong, Xiao; Wang, Wei ...
New journal of physics,
05/2018, Letnik:
20, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Recently, topological semimetals have become a hot topic in condensed matter physics, including Dirac semimetals, Weyl semimetals, and nodal line semimetals (NLSMs). In this paper, a new type of ...NLSM-type-II NLSM-is proposed based on a two-band cubic lattice model. For type-II NLSM, the zero energy bulk states have a closed loop in momentum space but the (local) Weyl cones on the nodal line become tilted. The effect of the magnetic field and that of the correlation on type-II NLSM are studied. In particular, after considering the repulsive interaction and additional spin degrees of freedom, different types of long range magnetic orders appear in bulk states. In addition, the interaction-induced ferromagnetic (FM) order of surface states may exist. At a critical point between type-I NLSM and type-II NLSM, arbitrary tiny interactions induce FM order due to a flat band at the Fermi surface.
Nonlinearity in complex systems leads to pattern formation through fundamental interactions between components. With integrated photonics, precision control of nonlinearity explores novel patterns ...and propels applications. In particular, Kerr-nonlinear resonators support stationary states—including Turing patterns—composed of a few interfering waves, and localized solitons composed of waves across a broad spectrum. Although Turing patterns emerge from an unstable Kerr resonator with sufficiently intense excitation, Kerr solitons do not form spontaneously under constant excitation, making this useful state challenging to access. Here we explore an edgeless photonic crystal resonator (PhCR) that enables spontaneous soliton formation in place of Turing patterns. We design the PhCR nanopattern for single-azimuthal-mode engineering of a group-velocity-dispersion defect that balances Kerr-nonlinear frequency shifts in favour of the soliton state. Our experiments establish PhCR solitons as modelocked pulses through ultraprecise optical-frequency measurements. We show that nanophotonics expand the palette for nonlinear engineering, enabling new phenomena and light sources.Researchers have demonstrated spontaneous soliton formation in an edgeless photonic crystal resonator.
In more than 400 older patients with AML who could not receive myeloablative therapy, the incidence of composite complete remission was higher (66.4% vs. 28.3) and the median overall survival was ...longer (14.7 vs. 9.6 months) among patients who received azacitidine plus venetoclax (a B-cell lymphoma 2 antagonist) than among those who received azacitidine alone.
Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal ...waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields
E
(
x
)
∝
e
±
i
k
x
x
outside the bandgap to localized fields
E
(
x
)
∝
e
−
κ
x
|
x
|
within the bandgap should be accompanied by a transition from largely dissipative atom–atom interactions to a regime where dispersive atom–atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D₁ line of atomic cesium for N̄ = 3.0 ± 0.5 atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom–atom interactions with low dissipation into the guided mode.
A Highly NIR Emissive Cu16Pd1 Nanocluster Peng, Su‐Kao; Yang, Hu; Luo, Dong ...
Small (Weinheim an der Bergstrasse, Germany),
03/2024, Letnik:
20, Številka:
13
Journal Article
Recenzirano
The construction of stable copper nanoclusters (Cu‐NCs) with near‐infrared (NIR) emission that can be used for catalysis is highly desired, yet remains a challenge. Herein, an atomically precise ...bimetallic Cu/Pd NC with a molecular formula of Cu16Pd1L10(PPh3)2(Pz)6 (Pz = 3,5‐(CF3)2Pyrazolate, L = 4‐CH3OPhC≡C−), abbreviated as Cu16Pd1, is synthesized. Single‐crystal X‐ray crystallographic analysis of Cu16Pd1 reveals a Cu10Pd1 kernel with pseudo‐gyroelongated square bipyramid confirmation surrounded by other 6 Cu(I) ions and protected ligands. Interestingly, it exhibits strong NIR emission with the highest photoluminescence quantum yield (PLQY) among all the Cu NCs/Cu alloys (λem > 800 nm) in the solid‐state, and also displays NIR emission in solution. Experimental results and theoretical calculations suggest that the impressive NIR emission is attributed to abundant supramolecular interactions in the solid‐state, including intramolecular metal–metal and intermolecular interactions. Of note, the bimetallic Cu16Pd1 can catalyze the reduction of 4‐nitrophenol. This work provides a novel method for synthesizing Cu/Pd NCs and reminds that the less studied Cu/Pd NC can serve as outstanding luminescent material, which is seldom noticed in atomically precise nanoclusters.
In this work, an atomically precise bimetallic Cu16Pd1 nanocluster with near‐infrared (NIR) emission both in solution and in solid‐state is synthesized, which is rarely observed in Cu clusters or Cu alloys. Moreover, the Cu16Pd1 nanocluster also displays high catalytic activity for the reduction of 4‐nitrophenol.
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