基于石墨烯可饱和吸收体的Er∶YAG被动调Q激光器

本文研究了一种采用氙灯侧泵方式,并基于石墨烯可饱和吸收体的Er∶YAG被动调Q激光器。首先成功将石墨烯转移至Al 2 O 3衬底制备得到石墨烯可饱和吸收体,并对其进行了形貌、结构及化学状态等性能表征。此外,对基于石墨烯可饱和吸收体的Er∶YAG被动调Q激光特性进行了研究,结果表明单脉冲能量从0.4 mJ增加至7 mJ,输出激光单脉冲宽度从761.2 ns下降至510 ns,最大峰值功率为13.7 kW。激光中心波长位于2935和2945 nm,且主波长在2935 nm处对应的半峰全宽(FWHM)为1.535 nm。沿x和y方向的光束质量因子分别为4.45和5.76。实验结果表明,该研究为推进更低成本、谐振腔设计简单且紧凑的2.94μm波段Er∶YAG激光器的发展提供了有效的参考依据。

Method for fitting crystal field parameters and the energy level fitting for Yb^(3+) in crystal Sc_2O_3

A method to compute the numerical derivative of eigenvalues of parameterized crystal field Hamiltonian matrix is given, based on the numerical derivatives the general iteration methods such as Levenberg-Marquardt, Newton method, and so on, can be used to solve crystal field parameters by fitting to experimental energy levels. With the numerical eigenvalue derivative, a detailed iteration algorithm to compute crystal field parameters by fitting experimental energy levels has also been described. This method is used to compute the crystal parameters of Yb^3＋ in Sc2O3 crystal, which is prepared by a co-precipitation method and whose structure was refined by Rietveld method. By fitting on the parameters of a simple overlap model of crystal field, the results show that the new method can fit the crystal field energy splitting with fast convergence and good stability.

A promising van der Waals two-dimensional nonlinear optical crystal NbOCl_(2) for ultrathin quantum light source

Nonlinear optical(NLO)crystals are the key fundamental materials in modern optoelectronic information technology,which play an irre-placeable role in modern quantum optics and photonics in addition to traditional laser frequency conversion applications[1,2].Especially at a time when the international competition of quantum information tech-nology is becoming increasingly intense,high-performing NLO crystals as the strategic materials for optical quantum technology have received continuous attention from physical chemists and materials scientists.

The compatibly large nonlinear optical effect and high laser-induced damage threshold in a thiophosphate CsInP_(2)S_(7)constructed with[P_(2)S_(7)]^(4-)and[InS_(6)]^(9-)

It is challenging to cooperatively improve the nonlinear optical(NLO)efficiency and the laser-induced damage threshold(LIDT).This work reports a novel IR NLO materials CsInP_(2)S_(7)(CIPS)designed by combination the strategies of alkali metals substitution and microscopic NLO units PS4 introduction based on AgGaS_(2).CIPS was composed of strongly distorted[InS_(6)]^(9-)octahedra and[P_(2)S_(7)]4-dimers constructed by corner-sharing[PS_(4)]^(3-),which increase the NLO efficiency and decrease thermal expansion anisotropy simultaneously.Compared with AgGaS_(2),CIPS exhibited strong phase matchable NLO response ca.1.1×AGS@2.1μm,high LIDT ca.20.8×AgGaS_(2),and IR transparency up to 15.3μm.Structural analysis and theoretical investigation confirmed that large SHG effect and ultrahigh LIDT of CIPS originated from the synergistic contribution of[InS_(6)]^(9-)octahedra and[P_(2)S_(7)]4-dimers.These results indicate that CIPS is a promising NLO candidate in the mid-IR region,and this study provides a new approach for developing potential NLO-LIDT compatible materials.

Deep-ultraviolet nonlinear optical crystals: concept development and materials discovery

Deep-ultraviolet (DUV, wavelength λ < 200 nm) nonlinear optical (NLO) crystal is the core component of frequency conversion to generate DUV laser, which plays an important role in cutting-edge laser technology and fundamental science. Significant progress has been made in both experimental exploration and theoretical design in the field of DUV NLO crystals over the past three decades. In-depth insight into “structure-property correlations”, in particular, allows for rigorous and precise identification of DUV NLO crystals. In this article, we reviewed the current experimental and theoretical research progress while elucidating the core concepts and stringent criteria of qualified DUV phase-matched second-harmonic generation crystals. We also discussed the development of the DUV NLO “structure-property correlations” from first principles and how it has sparked interest in related materials, as well as future directions for obtaining potential DUV NLO crystals.

Large sliding regulation in van der waals layered nonlinear optical ternary chalcogenides

Interlayer sliding modulation in van der Waals(vdW)layered materials opens opportunities to seek tunable applications for photonics and optoelectronics at the nanoscale.In this work,focusing on ternary chalcogenides,dozens of typical vdW layered materials with the formula of A_(2)MZ_(4)(A,M=metal cation;Z=S/Se)were systematically classified and studied to illustrate the interlayer sliding modulation performance on nonlinear optical(NLO)effect and underlying mechanism.Based on first-principles analysis,the screened Cd_(2)GeSe_(4) exhibits large second harmonic generation(SHG)deviation(>36 times between high-and low-SHG states)under sliding among all studied materials.This phenomenon arises from the polarization modulation induced by the vdW interlayer charge redistribution of two tetrahedral primitives in the ternary edge-sharing tetrahedral structures.Our findings present a strategy to substantially modulate NLO properties by altering the interlayer charge coupling which is commonly thought to be very weak in vdW layered materials.