Detailed electronic structure of three-dimensional Fermi surface and its sensitivity to charge density wave transition in ZrTe_3 revealed by high resolution laser-based angle-resolved photoemission spectroscopy

The detailed information of the electronic structure is the key to understanding the nature of charge density wave(CDW) order and its relationship with superconducting order in the microscopic level. In this paper, we present a high resolution laser-based angle-resolved photoemission spectroscopy(ARPES) study on the three-dimensional(3 D) hole-like Fermi surface around the Brillouin zone center in a prototypical quasi-one-dimensional CDW and superconducting system ZrTe_3. Double Fermi surface sheets are clearly resolved for the 3 D hole-like Fermi surface around the zone center. The3 D Fermi surface shows a pronounced shrinking with increasing temperature. In particular, the quasiparticle scattering rate along the 3 D Fermi surface experiences an anomaly near the charge density wave transition temperature of ZrTe_3(～ 63 K). The signature of electron–phonon coupling is observed with a dispersion kink at ～ 20 me V; the strength of the electron–phonon coupling around the 3 D Fermi surface is rather weak. These results indicate that the 3 D Fermi surface is also closely connected to the charge-density-wave transition and suggest a more global impact on the entire electronic structure induced by the CDW phase transition in ZrTe_3.     

Dark blue erenkov second harmonic generation in the two-layer-stacked hexagonal periodically poled MgO:LiNbO_3s

We report the dark blue nonlinearˇCerenkov radiation by the second harmonic generation(SHG)in a two-layer-stacked hexagonal periodically-poled-MgO:LiNbO3s(PPMgOLNs).Based on the direct wafer bonding of two target PPMgOLNs rotating around the axis perpendicular to the plane with an angle of 30°,twelve bright spots as twice of those in a single PPMgOLN are shown at each second-harmonicˇCerenkov ring.The experimental results agree with the theoretical ones and present a promising application in the fabrication of three-dimensional(3D)PPMgOLNs.     

Investigation on the scattering effect of ceramic Nd:YAG

This paper investigates the scattering effect of domestic 0.5 at{\%} ceramic Nd:YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave (CW) Nd:YAG ceramic laser was also demonstrated. A maximum output power of 6.7~W at 1064~nm was obtained at an 808-nm pump power of 32.9~W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd:YAG.     

紫外非线性光学晶体三硼酸铯的生长和性能

采用泡生法和提拉法生长出三硼酸铯(化学式CsB3O5,简称CBO)晶体,研究了晶体生长工艺条件及晶体生长形态.泡生法生长的CBO晶体的尺寸为40mm×25mm×25mm;生长过程中晶体转速为10～20r/min,降温速率为0.1～0.2℃/d.用提拉法生长出20mm×30mm的CBO晶体;生长过程中液面温度梯度为60℃/cm,提拉速度为8mm/d.在生长过程中Cs2O的挥发速度大于B2O3的挥发速度.CBO单晶的晶面由[011]斜方柱和[010]斜方柱单形组成,属于[011]单形是4个较大的面,属于[101]单形是4个较小的三角形晶面.CBO在紫外波段具有较大的有效非线性光学系数.利用CBO进行Nd∶YAG激光和频获得了高转换率的波长355nm及266nm相干光输出.     

初始啁啾对飞秒脉冲在光子晶体光纤中超连续谱产生的影响

采用分步傅里叶方法模拟了初始啁啾对光子晶体光纤中超连续谱产生的影响.根据光纤长度，将光子晶体光纤中脉冲的演化分成初始展宽、剧烈展宽和饱和展宽三个阶段.通过讨论啁啾脉冲和无初始啁啾脉冲在各阶段演化的区别，发现啁啾只在初始展宽和剧烈展宽阶段对光谱有影响，当β₂C<0时啁啾有利于光谱的展宽，当β₂C>0时则刚好相反，在饱和展宽阶段啁啾不再对光谱产生影响.要想利用啁啾脉冲来获得较宽的光谱，必须选择合适的光纤长度，使输出的脉冲处于剧烈展宽阶段.这为利用啁啾脉冲在光子晶体光 关键词： 超连续谱 光子晶体光纤 分步傅里叶法 啁啾     

High peak power laser-diode-pumped passively Q-switched Nd:YVO4/Cr4+:YAG laser

In this paper, we report a high peak power passively Q-switched laser-diode-end-pumped Nd:YVO4/Cr4+:YAG laser polarized along the C axis, generating 4.23-W average power and 18-kW peak power (144-μJ pulse power) with 8.0-ns time duration (29.4-kHz repetition rate) at 1064 nm while the pump power is 21.2 W.     

高功率垂直腔面发射半导体激光器优化设计研究

与传统的端发射半导体激光器相比，垂直腔面发射半导体激光器（VCSEL）具有可单模输出，光束对称性好，可被高度聚焦，进入光纤的耦合效率极高和有利于大规模二维列阵等优 点.为了得到高功率的激光输出，除了要增大VCSEL的发射面积之外，关键的是要选择适 当的量子阱层数、有源区电流密度的均匀分布和良好的热管理等.本文详细研究和分析了高功率VCSEL有源区量子阱层数，有源区直径，材料的热导和电阻，电极间距等对VCSEL 器件性能的影响.通过优化参数，进行最佳设计，研制出了980 nm In0.2Ga0.8As/Ga 关键词： 垂直腔面发射激光器（VCSEL） 量子阱 高功率     

VIFP型紫外-红外平面法布里-珀罗扫描干涉仪

一、引言法布里-珀罗干涉仪在光学和激光领域有着广范的用途。它可以用于高分辨率光谱学,测量波长和谱线的线型;用于压窄激光线宽,分析激光的模式;在啦曼散射、布里渊散射、以及瑞利散射等方面也经常用它测量线移和线型;此外,在天文学中亦有重要的应用。     

涡流稳定闪光灯抽运染料激光实验

采用闪光灯抽运染料激光,由于装置简单和总效率高而被广泛应用.但是,常用的闪光灯如同轴型[1]和直管型[2]咽电极溅射和灯管汽化,所以寿命短,爆炸能量低,不利于高功率高量复率运转.短弧闪光灯阻抗太低,难于电匹配,而且效率低.本文报道一台涡流稳定闪光灯[3,4],在一定程度上可克服上述缺点,可作为长寿命高平均功率染料激光的有效泵源. 图1是实验装置示意图,灯电极是直径为12mm的半球,阴极中心气孔直径为4mm,阳极周围有八个孔径为1mm与灯轴成75°的喷气口,其喷气方向在灯管切线方向,以保证在灯管内产生涡流,使灯轴线上造成较低气压,以令放电电…     

High peak power laser-diode-pumped passively Q=switched Nd:YVO_4/Cr~(4+):YAG laser

In this paper, we report a high peak power passively Q-switched laser-diode-end-pumped Nd:YVO_4/Cr~(4+):YAG laser polarized along the C axis, generating 4.23-W average power and 18-kW peak power (144-μJ pulse power) with 8.0-ns time duration (29.4-kHz repetition rate) at 1064 nm while the pump power is 21.2 W.