用Cr:YAG被动调Q的Yb:YAG激光

用连续钛宝石激光器作抽运源,在室温下用Cr4+:YAG作可饱和吸收体实现了Yb:YAG晶体的被动调Q激光输出。实验中获得了在1.03μm平均功率为55mW和脉宽(FWHM)为0.35μs的被动调Q激光。Cr:YAG的初始透过率对Yb:YAG被动调Q激光的脉宽(FWHM)和重复率有一定影响。实验表明Yb:YAG晶体是一种有前景的结构紧凑、高效和全固化的被动调Q激光晶体。     

体光栅输出被动Cr4+:YAG调Q单纵模Nd:YAG激光器研究

以Cr4+:YAG为饱和吸收体,体布拉格光栅为耦合输出窗,研究了被动调Q闪光灯泵浦Nd:YAG单纵模激光器.通过扭转模腔和体布拉格光栅相结合的方式获得单纵模输出,提高了单纵模输出能量及稳定性.对于不同初始透过率的Cr4+:YAG晶体,得到了单纵模输出能量和脉宽的曲线.单纵模激光最大线宽约为78 MHz.最大单纵模单脉冲输出能量为20.8 mJ,最小的脉宽为13.2 ns,最大峰值功率为1.18 MW.     

全固化微脉冲Nd:GdVO_4激光器

研究了在不同透过率被动调Q情况下,全固态Nd:GdVO4激光器输出功率和脉宽随泵浦功率变化的关系,在静态情况下得到了光光转换效率为53％的激光输出。并且得到最小调Q脉宽27.29 ns。     

LD光纤耦合端面泵浦Nd:YVO4/Cr4+:YAG激光器

根据Siegman的被动调Q判据,Nd:YVO4晶体由于受激发射截面大、上能级寿命短,很难获得被动调Q输出。利用LD光纤耦合端面泵浦Nd:YVO4晶体,在泵浦功率3.5W时,连续运转获得最大输出1.4W,相应的光光转换效率为40%,同时采用Cr4+:YAG可饱和吸收体,成功地实现了Nd:YVO4被动调Q运转,获得了脉宽11.7ns,重复频率22kHz调Q输出。     

稳定的高重频Cr4+:Nd3+:YAG自调Q激光器

在平平腔的Cr4+ Nd3+ YAG激光器中,采用内置f=70mm双凸透镜形成等效腔和用φ1mm小孔光阑进行横模限制的方法,获得了高重频、高光光转换效率、稳定的激光脉冲序列.在泵浦功率17.2W时,获得了平均功率4.7W,其光光转换效率达到了27.3%.此时的重复频率及其标准方差为42±1kHz,脉宽及其标准方差为9.57±0.187ns,示波器采集的光脉冲值幅度及其标准方差为471±36μW.对应的峰值功率和单脉冲能量分别达到了13kW和115μJ.据我们了解,这是迄今为止LD端面泵浦的自调Q激光器获得的重复频率最高且稳定的实验结果.     

1.3414μm Nd:YAlO3电光Q开关脉冲激光器

本文介绍了一种用LiNb％晶体作为电光Q开关晶体的闪光灯泵浦1．3414μm Nd：YAlO3,电光调Q脉冲激光器,实验得到了脉宽45ns、输出能量312mJ的巨脉冲激光输出。     

914nm LD端面抽运Nd:YVO4 100kHz皮秒再生放大器

采用Nd:YVO4晶体带内抽运波长914nm,降低激光二极管(LD)连续抽运时晶体的热负荷和端面热应力,提高高重复频率Nd:YVO4皮秒再生放大器输出性能。研究分析了普克尔盒加压脉宽对工作频率为100kHz的Nd:YVO4再生放大器输出脉冲稳定性的影响,在吸收914nm抽运功率为68W,通过控制普克尔盒加压脉宽,实现了对单脉冲能量为1nJ、脉宽为5.7ps、频率为42.7MHz的全固态Nd:YVO4半导体可饱和吸收镜(SESAM)锁模种子激光脉冲的稳定的100kHz皮秒激光再生放大,输出平均功率为21.2W。     

LD脉冲抽运的被动调Q Nd:YVO4激光器的研究

报道在LD脉冲抽运的Nd：YVO4激光器中插入Cr^4＋：YAG,获得稳定的调Q激光输出。在输出镜透过率T=10％时,插入Cr^4＋：YAG的调Q阈值为19．1mJ,在抽运能量为34mJ时,测得脉冲宽度为38ns,输出能量为0．34mJ。实验研究了脉冲宽度随抽运能量的变化,并比较了不同透过率输出镜条件下Cr^4＋：YAG调Q的输出能量和调Q效率随抽运能量的关系。实验还把Cr^4＋：YAG换成BDN染料片,获得了比Cr^4＋：YAG调Q还窄的10ns左右的脉冲,并根据Cr^4＋：YAG和BDN染料片的调Q机理对一些实验现象作出合理的解释。     

主-被动对撞脉冲锁模Nd:YAG激光器

报道主-被动和纯被动对撞脉冲锁模Nd~(3+)∶YAG激光器的实验研究结果.主-被动锁模激光脉宽为15ps,激光输出序列脉冲能量起伏小于±2%.被动锁模激光脉宽为12ps,序列脉冲能量起伏小于±1O%.利用腔内插入标准具,获得脉宽在15～26ps间可变的锁模激光.实验还研究了非共振环形腔的激光偏振特性.     

LD抽运的Nd:YLF/Cr4+:YAG被动调Q激光器

报道了激光二极管（LD）抽运的Nd：YLF激光器,采用平凹腔结构,分别用两片Cr^4＋：YAG可饱和吸收晶体,实现了被动调Q,输出激光波长为1053nm。采用厚度为0．5mm小信号透过率为90％的Cr^4＋ YAG,在泵浦功率最大为17W时,输出脉冲宽度为60．6ns,平均功率为1．5W,重复频率为9．5kHz,单脉冲能量为157．9mJ;采用厚度为0．55mm小信号透过率为95％的Cr^4＋ YAG,在泵浦功率最大为17W时,输出脉冲宽度为68．6ns,平均功率为1．35W,重复频率为14kHz,单脉冲能量为96．4mJ。     

Careers: Survivor: The Office

Each of us must contend with office politics, because human beings are political animals, and we form alliances, negotiate deals, demand tribute, and wreak revenge. This paper discusses short list of political do's and don'ts.     

The electronic and magnetic properties of wurtzite Mn∶CdS,Cr∶CdS and Mn∶Cr∶CdS∶ first principles calculations

In this article, density functional theory (DFT) based on generalized gradient approximation (GGA) and GGA+U, U is Hubbard term, is used to study the electronic properties of CdS doped with different dopants (Cr, Mn). The calculations are carried out for Mn-doped CdS, Cr-doped CdS, and co-doping of Mn/Cr in CdS simultaneously. It is found that hopping of electrons is possible with Cr:CdS and Mn:Cr:CdS while Mn:CdS does not allow the hopping of electrons. Moreover, double exchange interactions are observed in Cr:CdS and d-d super-exchange interactions are observed in Mn:CdS. Now the problem becomes interesting when one magnetic ion (Cr) supporting double exchange interactions and another ion (Mn) supporting d-d super-exchange interactions are doped simultaneously in the same system (CdS). The co-doped CdS is more stable even at high Curie temperature due to p-d double exchange interactions and d-d super exchange interactions. Furthermore, the Cr-3d and Mn-3d states present in-between the band gap are responsible for inner shell transitions and hence for optical properties. Therefore, the co-doped system is taken into account to enhance its applications in the field of spintronic and magneto-optical devices.     

SCTS:: scanning capacitance transient spectroscopy

A new working mode of scanning capacitance microscopy (SCM) is presented, extending the possibilities of the measurement from lock-in amplitude mapping to recording of capacitance transients arising as response of abrupt bias changes. Effect of Au doping in Si on SCM and scanning capacitance transient spectroscopy (SCTS) was observed. The decay time of capacitance transient, measured locally on slightly doped region shows good agreement with the conventional DLTS results.