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We used low-temperature ultrahigh-resolution (360 microeV) photoemission spectroscopy with a laser as a photon source (Laser-PES) to study the superconducting (SC) gap of an f-electron superconductor CeRu2. The unique combination of the large escape depth expected from the known universal behavior and extremely high-energy resolution has enabled us to directly measure the bulk SC gap of an f-electron superconductor for the first time. The present study provides direct evidence for an anisotropic SC gap in CeRu2, and also demonstrates the potential of Laser-PES in investigating unconventional superconductivity realized in correlated d- and f-electron superconductors.

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We have demonstrated the second harmonic of a frequency-tripled Nd:YVO4 laser with 2.5-mW quasi-cw output by using an optically contacted, prism-coupled KBe2BO3F2 crystal. We also achieved the second harmonic with a frequency-doubled single-mode Ti:sapphire laser at 172.5 nm and sum-frequency mixing with a dual-wavelength Ti:sapphire laser at 163.3 nm. These wavelengths are to our knowledge the shortest obtained by use of nonlinear crystals for second-harmonic generation and sum-frequency mixing, respectively.

The research of functional magnetic materials has become a hot topic in the past few years due to their fast, long‐range, and precise response in diverse environments. Functional magnetic devices using different magnetic materials and structure designs have been developed and demonstrated good advantages to enable various applications. However, the required magnetic materials and structure designs for diverse functions also increase the fabrication difficulties while developing such devices. 3D printing technology presents a powerful and promising manufacturing approach to rapidly fabricate functional magnetic devices of complex geometries in multiple materials and scales. Here, various 3D printing strategies and the underlying mechanisms of functional magnetic materials for several primary applications are systematically reviewed, including, magnetic anisotropy for property enhancement, magnetic robots, magnetic components in electronics, and magneto‐thermal devices. Finally, the current challenges and future perspectives in engineering 3D printed functional magnetic devices are discussed.

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For van der Waals (vdW) heterostructures, optical and electrical properties (e.g., saturable absorption and carrier dynamics) are strongly modulated by interlayer coupling, which may be due to effective charge transfer and band structure recombination. General theoretical studies have shown that the complementary properties of graphene and MoS 2 enable the graphene/MoS 2 (G/MoS 2 ) heterostructure to be used as an important building block for various optoelectronic devices. Here, density functional theory was used to calculate the work function values of G/MoS 2 with different thicknesses of MoS 2 , and its relaxation dynamic mechanism was illustrated. The results reveal that the G/MoS 2 heterostructure interlayer coupling can be tuned by changing the thickness of MoS 2 , furthering the understanding of the fundamental charge-transfer mechanism in few-layer G/MoS 2 heterostructures. The tunable carrier dynamics and saturable absorption were investigated by pump−probe spectroscopy and open-aperture Z-scan technique, respectively. In the experiments, we compared the performances of Q-switched lasers based on G/MoS 2 heterostructures with different MoS 2 layers. Taking advantage of ultrafast recovery time and good saturable absorption properties, a femtosecond solid-state laser at 1.0 μm with G/MoS 2 heterostructure saturable absorber was successfully achieved. This study on interlayer coupling in G/MoS 2 may allow various vdW heterostructures with controllable stacking to be fabricated and shows the promising applications of vdW heterostructures for ultrafast photonic devices. KEYWORDS: G/MoS 2 heterostructure, nonlinear optical response, femtosecond solid-state bulk laser, saturable absorption, charge-transfer process

A new nonlinear optical crystal BaTeMo2O9 was grown from the TeO2−MoO3 flux system with sufficient size (30 × 23 × 18 mm3) and optical quality that allowed the characterization of its properties. It crystallizes in the noncentrosymmetrical system, space group P21 (no. 4), with a = 5.5346 Å, b = 7.4562 Å, c = 8.8342 Å, and β = 90.897°. The as-grown BaTeMo2O9 crystal has well-developed faces with the major forms {100}, {001}, {011}, and {011̅}. The transmission spectra results suggest that it can transmit well from 0.5 to 5.0 µm. The refractive indices were also measured. The smaller refractive indices nx and ny are in the ac-plane, and the largest refractive index nz polarization direction is parallel to the crystallographic b-axis.