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Chinese sports market gained tremendous attention in recent days as China held the 2022 Winter Olympic Games successfully. However, in contrast to other sports markets, the attention given to the Chinese Super League (CSL), the top-division soccer league in China, seems to have decreased catastrophically. The CSL was once popular among the public in its golden era but met a recession in recent years. Service quality and brand equity were two of the major factors that directly influenced spectators' experiences in the western market, followed by previous studies. The study from Grönroos suggests that service quality has three dimensions: functional, technical, and image. The study from Keller suggests that brand equity was built by consumers based on their knowledge and experience of a brand. From former empirical research, it is unsure if those models fit different occasions in China, and whether the depression of the CSL can be explained by the missing aspects of service quality and brand equity. The results from review actions by CSL revealed that both thrive of the CSL and the recession of the CSL followed by brand equity and service quality model. Meanwhile, several suggestions have been raised based on the two models that can be implemented to help the CSL out of catastrophe.

LaAeAl3S7 IR NLO thioaluminates with unprecedented Cairo pentagonal layers exhibit a good balance between a strong SHG response and a wide bandgap.

Salt-inclusion NLO thiosilicate [Sr4Cl2][Si3S9] with an unprecedented tri-polymerized [Si3S9] cluster shows a good balance between an ultrawide bandgap and large SHG response.

A synergetic effect of composition engineering and crystal engineering is proposed to grow uniaxially oriented FAxMA1−xPbI3 films with low intragrain and structural defects, which exhibit a superior self-powered photoresponse.

A linear relationship connecting the properties of composition and spectrum was deduced in Yb3+-doped sesquioxide crystals, and the emission spectra of Yb:LuxY2−xO3 crystals broadened under the effects of crystal field and electron–phonon coupling.

We report a high-power self-frequency-doubled (SFD) Yb:YCa4O(BO3)3 laser by employing a simple and high-integration monolithic configuration with an oscillator length of 6 mm. By reducing the reabsorption and increasing the quantum efficiency, the continuous-wave output power of 21.6 W was obtained with an optical conversion efficiency of 19.0% at the wavelength of about 510 nm. To our knowledge, the results represent the highest output power of a SFD laser. We believe that the high-power SFD laser with a highly compact structure will have broad and promising application prospects in laser display, medical treatment, spectral analysis, scientific research, and other fields.

Surface nonlinear optics lays at the heart of integrated photonics and micro-nano optoelectronics, whose efficiency is restricted by the finite nonlinear susceptibility of matter and the intrinsic atomic-layered interaction length between light and matter. Herein, we originally demonstrate that the centrosymmetric topological semimetal HfGe0.92Te crystal possesses a giant and anisotropic surface second-order nonlinear susceptibility up to 5535 ± 308 pm·V− 1 and manifests efficient and unprecedented second-harmonic generation (SHG) based on the angular engineering strategy. The maximum optical conversion efficiency is up to 3.75‰, a value that is 1015 orders of magnitude larger than the conventional surface SHG. Benefiting from the linear dispersion in a large energy range around the Dirac points, we find that this high conversion efficiency can be maintained with the SHG wavelengths ranging from the visible region to the deep ultraviolet one (515 nm-257.5 nm). Our work may open the door for the development of topological photonics and integrated nonlinear photonics based on topological semimetals.

Revealing the interaction between electrons and phonons, e.g., electron-phonon coupling or decoupling, is a great challenge for physics and functional material communities. For rare-earth single crystals, the electron-phonon coupling and fluorescence behaviors strongly depend on the crystal structure and constituent motifs. Here, we proposed a universal "quasi-free O" as an effective structural motif to enhance phonon-assisted electronic transitions and photoluminescence. Using Gd

Electron-phonon coupling emerges as a growing frontier in the heart of condensed matter from physical symmetry to the electronic quantum state, but its quantitative strength dependence on the chemical structure has not been assessed. Here, we originally proposed the anion-centered polyhedron (ACP) strategy for elaborating the electron-phonon coupling interaction in rare-earth (RE) materials comprising three chemical factors, RE-O bond length, the effective charge of the coordinated atom, and structural dimensionality. Using Gd

Materials based on group IV chalcogenides exhibit extensive technologically important properties. Its unusual chemical bonding and off-centering of in-layer sublattices could cause chemical polarity and weakly broken symmetry, making optical field controlling feasible. Here, we fabricated large-area SnS multilayer films and observed unexpected strong SHG response at 1030 nm. The appreciable SHG intensities were obtained with an independence on layer, which is opposite to the generation principle of overall nonzero dipole moment only in odd-layer material. Taking GaAs for reference, the second-order susceptibility was estimated to be 7.25 pm/V enhanced by mixed-chemical bonding polarity. Further polarization-dependent SHG intensity confirmed the crystalline orientation of SnS films. The results imply surface inversion symmetry broken and nonzero polarization field modified by metavalent bonding should be the origin of SHG responses. Our observations establish multilayer SnS as a promising nonlinear material, and will guide in design of IV chalcogenides with improved optics and photonics properties for the potential applications.

Coupling between electronic motions and the lattice vibrations, phonons could broaden the spectral bandwidth of the fluorescence spectroscopy by the energy transferring, which was recognized from the beginning of last century and successfully applied in many vibronic lasers. However, the laser performances under electron-phonon coupling were mainly prejudged by the experimental spectroscopy. The multiphonon participated lasing mechanism is still elusive and should be in-depth investigated. Here, a direct quantitative relationship between the laser performance and phonon participating dynamic process was derived in theory. With a transition metal doped alexandrite (Cr3+:BeAl2O4) crystal, the multiphonon coupled laser performance was manifested in experiments. Associated with the Huang-Rhys factor calculations and hypothesis, the multiphonon participated lasing mechanism with phonon numbers from 2 to 5 was discovered and identified. This work provides not only a credible model for understanding the multiphonon participated lasing, but should also boost the study of laser physics in the electron-phonon-photon coupled systems.

We report on a Kerr-lens mode-locked laser based on an Yb3+-doped disordered calcium lithium niobium gallium garnet (Yb:CLNGG) crystal. Pumping by a spatially single-mode Yb fiber laser at 976 nm, the Yb:CLNGG laser delivers soliton pulses as short as 31 fs at 1056.8 nm with an average output power of 66 mW and a pulse repetition rate of ∼77.6 MHz via soft-aperture Kerr-lens mode-locking. The maximum output power of the Kerr-lens mode-locked laser amounted to 203 mW for slightly longer pulses of 37 fs at an absorbed pump power of 0.74 W, which corresponds to a peak power of 62.2 kW and an optical efficiency of 20.3%.

A gyroscope is one of the core components of an inertial navigation system. Both the high sensitivity and miniaturization are important for the applications of the gyroscope. We consider a nitrogen-vacancy (NV) center in a nanodiamond, which is levitated either by an optical tweezer or an ion trap. Based on the Sagnac effect, we propose a scheme to measure the angular velocity with ultra-high sensitivity through the matter-wave interferometry of the nanodiamond. Both the decay of the motion of the center of mass of the nanodiamond and the dephasing of the NV centers are included when we estimate the sensitivity of the proposed gyroscope. We also calculate the visibility of the Ramsey fringes, which can be used for estimating the limitation of gyroscope sensitivity. It is found that the sensitivity ∼ 6.86 × 10 − 7 r a d / s / H z can be achieved in an ion trap. As the working area of the gyroscope is extremely small (∼0.01~μm2), it could be made on-chip in the future.

We report on a Kerr-lens mode-locked Yb:CLNGG laser generating 35-fs pulses at 1060.2 nm with an average output power of 85 mW at a pulse repetition rate of ~77.7 MHz.

We report on the spectroscopy and continuous-wave laser operation of Yb:YGG crystal at cryogenic temperatures. At 120K, in CW laser regime, a maximum output of 17.5W corresponding to a slope efficiency of 73% was achieved.

We report on a high-power first-order Laguerre-Gaussian beam generation from a diode-pumped Tm:YAlO3 laser with a maximum power of 16.7 W at 1987 nm. Wavelength tunable operation is achieved across ~149 nm.

Ytterbium (Yb)-ions-doped sesquioxide crystal is an attractive gain medium for a tunable and pulsed laser owing to its high thermal conductivity. In particular, it has been identified that Yb:LuScO3 has the largest energy storage property compared with other sesquioxide crystals, which is favorable for passive Q switching. In this Letter, continuous wave (CW) and the first, to the best of our knowledge, passively Q switched laser operations were demonstrated with a Yb:LuScO3 crystal. For CW laser operation, it generated the maximum output power of 8.68 W, corresponding to a slope efficiency up to 78.3%. Using Cr:YAG crystals as saturable absorbers, stable passive Q switching lasers were obtained with the Yb:LuScO3 crystal. Both the CW and Q switched lasers operate on the strongest fluorescence emission peak of 1038 nm. With Cr:YAG as the saturable absorber, efficient passively Q switched lasers with a slope efficiency of 45% were obtained with the pulse width, pulse energy, and peak power of 5.9 ns, 116 µJ, and 18.5 kW, respectively.

We report the first, to the best of our knowledge, laser operation of acentric Yb3+-doped La2CaB10O19 (Yb:LCB) crystal since its discovery in 1998. The polarized absorption and emission cross-section spectra of Yb:LCB were calculated at room temperature. Using a fiber-coupled 976 nm laser diode (LD) as the pump source, we realized effective dual-wavelength laser generation at around 1030 and 1040 nm. The highest slope efficiency of 50.1% was obtained in the Y-cut Yb:LCB crystal. In addition, via resonant cavity design on a phase-matching crystal, a compact self-frequency-doubling (SFD) green laser at 521 nm was also realized in a single Yb:LCB crystal with an output power of 152 mW. These results promote Yb:LCB as a competitive multifunctional laser crystal, especially for highly integrated microchip laser devices ranging from the visible to the near-infrared regime.

In this Letter, a continuous-wave Yb:ScBO3 laser was enhanced with a maximum output power of 1.63 W and a slope efficiency of 48.97%, pumped by a continuous-wave 965 nm diode laser. Subsequently, the first, to the best of our knowledge, acousto-optically Q-switched Yb:ScBO3 laser was realized with an output wavelength of 1022 nm and repetition rates ranging from 0.04 to 1 kHz. The characteristics of pulsed lasers modulated by a commercial acousto-optic Q switcher were comprehensively demonstrated. With a low repetition rate of 0.05 kHz, the pulsed laser was generated under an absorbed pump power of 2.62 W, having an average output power of 0.44 W and giant pulse energy of 8.80 mJ. The pulse width and peak power were 80.71 ns and 109 kW, respectively. The findings manifest that the Yb:ScBO3 crystal is a gain medium with great potential for Q-switched laser generation with high pulse energy.

Laser damage threshold (LDT) is critical for optical devices in high-intensity laser applications. Understanding the influence mechanism of a high-intensity laser on optical materials is principal for improving the materials’ LDTs. Here, the LDT of La3Ga5.5Nb0.5O14 (LGN) crystals, the most promising nonlinear optical material for mid-infrared optical parametric chirped-pulse amplification (OPCPA), were studied, and its laser damage mechanism was elucidated. Oxygen vacancies in different ligands have important and distinct effects on LDTs and introduce defect levels, playing primary roles in the reduction of LDTs by the absorption of electrons in the conduction bands. The formation of F-centers also decreases LDTs via two-photon absorption. In addition, the linear absorption of free electrons in the conduction bands contributes more than the two-photon absorption, induced by the defect level, in the nanosecond laser damage process. By annealing in optimized conditions, the 0% laser damage probability of the LGN crystals was measured up to 13.1 J/cm2, which is a 24% improvement compared with that of the as-grown sample, and the highest of the mid-infrared nonlinear optical crystals. The results can not only lead to further improvements in the laser amplification properties in OPCPA systems but also inspire further studies on the application of optical materials in high-intensity lasers.

Over the past decades, Yb3+-doped cubic sesquioxide crystals have been considered as ideal gain materials for ultrafast laser generation, owing to their high thermal conductivity and adequate optical characteristics. The broadening of spectra by mixing host crystals to obtain short pulses has been extensively explored; however, few studies have examined the mechanism of the crystal field effect on spectral broadening. This paper describes the spectral broadening process caused by the combination of the discrete transition peaks induced by the crystal field effect and electron-phonon coupling widening based on Yb:LuxSc2-xO3 crystals. The energy level splitting induced by the crystal field effect not only determines the emission peak positions, but also broadens the emission spectra in the mixed host materials through the increasing spin-orbit coupling effect. Moreover, with the involvement of the electron-phonon coupling and the crystal field effect, the spectral broadening is much more obvious at room temperature. These results not only explain the spectral broadening mechanism of Yb3+-doped sesquioxides but also provide important insights for the improvement of new ultrafast laser materials.

We reported a high repetition rate diode-pumped alexandrite femtosecond laser using a simple linear cavity. Laser emission spectrum was as broad as ∼20 nm by inserting a 0.5-mm-thick quartz birefringent plate as a spectral modulation component. Pulse duration as short as few-cycle 36 fs with the repetition rates of 2.48 GHz was measured at pump power of 17 W. To the best of our knowledge, this is the shortest pulse duration achieved in the alexandrite lasers.

Optical parametric chirped-pulse amplification (OPCPA) can be used to generate ultrafast intense mid-IR lasers, however, the lack of suitable nonlinear optical crystals simultaneously having a wide transmission range, high laser damage threshold, and excellent phase-matching property hinders the development of mid-IR OPCPA. Here, we focus on the La3Nb0.5Ga5.5O14 (LGN) crystal and describe its growth, characterization, and application in mid-IR nonlinear frequency converters. We discuss the optimization of the starting polycrystalline component and temperature field aimed for the growth of large-size LGN crystals with a 60 mm diameter. We then present a detailed characterization of their optical properties, including transmission spectrum, refractive indices, and nonlinear coefficient. Our findings suggest the promising potential of LGN in generating both few-cycle pulses across 3 to 6 µm and terawatt-class OPCPA systems around 5 µm.