In this work, hierarchical core-shell NiMoO@Ni-Co-S nanorods were first successfully grown on nickel foam by a facile two-step method to fabricate a bind-free electrode. The well-aligned electrode wrapped by Ni-Co-S nanosheets displays excellent nanostructural properties and outstanding electrochemical performance, owing to the synergistic effects of both nickel molybdenum oxides and nickel cobalt sulfides. The prepared core-shell nanorods in a three-electrode cell yielded a high specific capacitance of 2.27 F cm (1892 F g) at a current density of 5 mA cm and retained 91.7% of the specific capacitance even after 6000 cycles. Their electrochemical performance was further investigated for their use as positive electrode for asymmetric supercapacitors. Notably, the energy density of the asymmetric supercapacitor device reached 2.45 mWh cm at a power density of 0.131 W cm, and still retained a remarkable 80.3% of the specific capacitance after 3500 cycles. There is great potential for the electrode composed of the core-shell NiMoO@Ni-Co-S nanorods for use in an all-solid-state asymmetric supercapacitor device.

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Stimulated Raman scattering (SRS) has attracted increasing attention in bio-imaging because of the ability toward background-free molecular-specific acquisitions without fluorescence labeling. Nevertheless, the corresponding sensitivity and specificity remain far behind those of fluorescence techniques. Here, we demonstrate SRS spectro-microscopy driven by a multiple-plate continuum (MPC), whose octave-spanning bandwidth (600-1300 nm) and high spectral energy density (∼1 nJ/cm-1) enable spectroscopic interrogation across the entire Raman active region (0-4000 cm-1), SRS imaging of a Drosophila brain, and electronic pre-resonance (EPR) detection of a fluorescent dye. We envision that utilizing MPC light source will substantially enhance the sensitivity and specificity of SRS by implementing EPR mode and spectral multiplexing via accessing three or more coherent wavelengths.

Stimulated Raman scattering (SRS) spectromicroscopy is a powerful technique that enables label-free detection of chemical bonds with high specificity. However, the low Raman cross section due to typical far-electronic resonance excitation seriously restricts the sensitivity and undermines its application to bio-imaging. To address this bottleneck, the electronic preresonance (EPR) SRS technique has been developed to enhance the Raman signals by shifting the excitation frequency toward the molecular absorption. A fundamental weakness of the previous demonstration is the lack of dual-wavelength tunability, making EPR-SRS only applicable to a limited number of species in the proof-of-concept experiment. Here, we demonstrate the EPR-SRS spectromicroscopy using a multiple-plate continuum (MPC) light source able to examine a single vibration mode with independently adjustable pump and Stokes wavelengths. In our experiments, the CC vibration mode of Alexa 635 is interrogated by continuously scanning the pump-to-absorption frequency detuning throughout the entire EPR region enabled by MPC. The results exhibit 150-fold SRS signal enhancement and good agreement with the Albrecht A-term preresonance model. Signal enhancement is also observed in EPR-SRS images of the whole Drosophila brain stained with Alexa 635. With the improved sensitivity and potential to implement hyperspectral measurement, we envision that MPC-EPR-SRS spectromicroscopy can bring the Raman techniques closer to a routine in bio-imaging.

By virtue of its unique advantages such as natural abundance and mature fabrication engineering, silicon (Si) is widely utilized in the electronic industries. However, in the field of photonics, the indirect bandgap nature of Si prohibits emissionrelated applications. Despite this limitation, Si exhibits a relatively high refractive index that allows efficient light confinement, especially in nanostructures. [1][2][3] The strong confinement and accompanying field localization offer substantial enhancement of the intrinsically weak optical nonlinearity in Si, including twophoton absorption, [4,5] harmonic generation, [6] and photothermal effects, [7,8] leading to the emerging field of nonlinear Si nano-photonics [3] with applications covering all-optical switching, wavelength conversion, and superresolution imaging.Conventionally, optical nonlinearity is characterized via intensity-scan methods such as z-scan, [9,10] which is suitable to investigate thin-film samples. In the z-scan method, a thin sample moves along the propagation direction (z-axis) of a focused laser beam, and z-position dependent transmittance or divergence Nonlinear silicon nano-photonics has recently attracted significant attention due to the plethora of electric and magnetic Mie resonances that offer substantial enhancement of optical nonlinearities. Conventionally, the characterization of nonlinearity and its transient nature rely on intensity-scan methods (z-scan) in the spatial domain and pump-probe techniques in the temporal domain. However, most studied ultrafast nonlinear effects are instantaneous, that is, strongest at zero pump-probe delay, and have a solitary nonlinear power dependency (square, cubic, etc.). Here the authors found that when relaxation lifetime is dependent on pump fluence, transient nonlinearity appears. The effect is exemplified via Auger-based nonlinear carrier dynamics of a nano-silicon Mie-resonator. The Auger-induced transient nonlinearity not only locates at the time delay of several tens of picoseconds, but also displays diverse nonlinearities, including sub-linear, super-linear, and surprisingly full saturation, which features a "crossing point" where the probe scattering is pump-fluence independent. The crossing point exists when the relaxation lifetime is inversely dependent to second power of carrier density. Combining confocal intensity-scan (x-scan) and pump-probe temporal scan, the authors demonstrate that sub-linearity and super-linearity lead to swelled and reduced full-width-at-half-maximum (FWHM) of single-nanostructure images, further confirming the nonlinearity as well as the potential of sub-diffraction microscopy. The results open up a new avenue in nonlinear silicon nano-photonics by adding new degrees of freedom in temporally tuning the types of transient nonlinearities, which are valuable in all-optical signal processing and nano-imaging.