Study on a broad-area laser diode with external cavity feedback

The external cavity feedback of a broad-area laser diode is investigated. In Fourier optic methods, the inserted prism in an external cavity can be interpreted as a spatial filter in the Fourier plane of the laser diode. The transverse mode can be selected by changing the position of the filter. As the result of a self-consistency theoretical analysis, the output beam of the external cavity has a single-lobed far-field profile. It agrees well with the experiment result. The beam times-diffraction-limit-factor M² is measured to be 1.16.     

Improvement of the beam quality of a broad-area diode laser using asymmetric feedback from an external cavity

In this work, the use of an asymmetric feedback technique for improving the beam quality of a broad-area diode laser is investigated using numerical simulations. A mirror stripe is placed in the external cavity to select lateral mode and provide asymmetric feedback. The width and the position of the mirror stripe are optimized to improve the beam quality. The simulation results show a good beam quality of 0.7° FWHM and M ² value of 2.69.     

In-phase output beam from broad-area diode array using Talbot cavity

The robust phase locking of a linear diode array consisting of 49 broad-area emitters was demonstrated.The single lobe in the far field with output power of 0.83 W was observed. The far-field divergence was reduced to 2.0 mrad. The spectral bandwidth was reduced from 1.7 to 0.13 nm.     

光纤激光器阵列的多抖动法相干合成

采用自行设计的基于大规模可编程门阵列（FPGA）结构的控制电路,实现了4路光纤激光的多抖动法相干合成。对大气湍流和机械振动引起的相位噪声进行了有效补偿,使远场光斑条纹对比度由开环时的0.21提高到了闭环时的0.93,闭环时远场特定孔径内的能量较开环时提高了3.3倍。该方法还对人为抖动光纤引起的较高频率噪声具有很好的抑制作用,系统闭环后,远场光斑条纹对比度可达到0.72。     

Spectral beam combining of a broad-stripe diode laser array in an external cavity

The outputs from an 11-element, linear diode laser array with broad stripes have been beam combined into a single beam with a beam quality of ~20x diffraction limited in the plane of the junction. This beam combining was achieved by use of a common external cavity containing a grating, which simultaneously forces each array element to operate at a different, but controlled, wavelength and forces the beams from all the elements to overlap and propagate in the same direction. The power in the combined beam was 50% of the output from the bare laser array.     

600 kV波形可调快前沿脉冲源的研制

介绍了一种波形可调的高电压快前沿脉冲源。该脉冲源由Marx发生器、脉冲成型组件、主开关、匹配负载、分流电阻、串联电感等部件构成。各部件自成一体,呈模块化分布。以Marx发生器作为初级储能,通过调节发生器输出端分流电阻、串联电感及脉冲成型组件等模块,可以输出包括双指数波和方波在内的5种脉冲波形。输出脉冲幅值在200~600 kV范围内可调,最小脉冲前沿可达2 ns。     

半导体激光器列阵在外腔下的光谱特性

使用普通高反镜作为19个单元的半导体激光器列阵(LDA)的外腔,通过调节高反镜的位置和角度,使LDA发出的光反馈回有源层,从而压窄了输出光谱并降低了LDA的阈值电流.实验中,运行于外腔下的LDA在不同的驱动电流下的输出光谱均被压窄到了原来的1/10左右,阈值电流从7 A降到了5.5 A,并且在9 A的偏置电流下输出功率提高了2倍.     

利用外腔改善半导体激光器列阵的远场特性

采用一个由快轴准直透镜和一个高反射率平面镜组成的简单外腔,在腔长为几个cm时实现了半导体激光器列阵中部分单元的锁相运行;DLA远场出现了3个瓣,每瓣发散角为10 mrad左右,对比度为50%;通过控制部分单元的输出,可以抑制旁瓣的能量.     

0.02 nm带宽近衍射极限输出的双外腔反馈半导体激光器

实验研究了宽接触条形双外腔反馈半导体激光器,在该激光器的输出表面镀增透膜,反馈是由高反射率平面镜和闪耀光栅组成,通过调整平面镜和光栅的倾斜角度,使得特定的空间模式和纵模注入半导体激光器,使之产生振荡,并抑制了激光腔内振荡的其他横模和纵模数,从而输出单瓣近衍射极限的激光束。同时在腔内插入标准具,使得输出激光线宽达到0.02 nm,输出功率在150 mW。输出光束的光束质量因子M2为1.16。     

切削用量对铝靶表面质量的影响

采用单点金刚石切削技术，完成了对ICF实验用铝靶的切削加工，重点研究了切削用量对加工表面质量的影响。实验结果表明:采用较小的进给速度，较大的主轴转速能够获得较低的表面粗糙度，切削深度对表面质量影响较小。通过Form Talysurf 表面轮廓仪测量，结果表明表面粗糙度小于50 nm。     

外腔锁相宽发光区二极管激光列阵研究

利用简单的外腔,实现了具有宽发光区的商用半导体二极管激光列阵(DLA)的外腔锁相。光谱测量表明,DLA的谱宽由自由运行时的1.9 nm压缩到了0.16 nm,峰值波长由803.8 nm调整到805.5 nm;实测远场光瓣间角距等于1.6 mrad,即波长与发光单元间距之比,表明列阵运行在基超模(或最高阶超模);峰谷结构调制度大于0.8。观察表明,外腔长度在1/10~1/6泰伯距离内变化时,锁相均能实现。实验事实表明锁相是交叉注入锁定的结果。利用半导体激光注入锁定理论,定性分析了外腔DLA由自由振荡向锁相过渡的过程,预言了锁相场波长应出现在自由运行DLA光谱长波端,实验也证实了这一事实。     

一种实现光纤激光器高功率输出的方法

介绍了一种实现光纤激光器高功率输出的新方法——采用螺旋芯光纤，这种光纤是在光纤制作过程中按照一定的弯曲半径使纤芯呈螺旋状排布在光纤包层中。介绍了这种螺旋芯光纤的原理和其提高输出功率的能力，以及目前的理论与实验研究现状。基于该光纤，提出了一种光纤激光器相干合成新思想。     

High beam quality broad-area diode lasers by spectral beam combining with double filters

A modified spectral beam combining(SBC) approach based on double asymmetrical filters was proposed. By using this scheme, the high-order lateral modes at the edge of the far-field pattern can be suppressed in the external cavity, and the beam quality in the slow-axis direction was improved from 16.1 to 13.4 compared to the conventional SBC. In the meanwhile, the electrical-to-optical efficiency from the modified SBC was more than 40% with an output power of 34.1 W, which is similar to that of the conventional SBC.     

二极管激光阵列在Talbot外腔中同相模的选择

 从理论和实验上对二极管激光阵列在Talbot外腔中的锁相进行了研究。在同相模和异相模近场分布的基础上,利用1维情况下的菲涅耳衍射公式计算了其远场分布。根据同相模和异相模在Talbot腔中的分布特性,采用1/2 Talbot腔并将外腔镜倾斜一个角度a的方法既能选择同相模,又能使模式的功率损耗最小。二极管激光阵列芯片采用CD金刚石材料,“三明治”结构对其进行封装,明显地减小了阵列的“smile”效应。在实验中实现了二极管激光阵列同相模的锁相输出,远场单瓣模的半高全宽为0.11 mm。     

Grating feedback in a 810 nm broad-area diode laser

Narrow linewidth, single spectral mode operation has been obtained in a high power, 810 nm broad-area diode laser in an extended cavity configuration with a grating as external reflector (grating feedback). For stable operation it was necessary to misalign the feedback slightly in the plane of the laser junction. Characteristics of the thus obtained laser system are a linewidth below 5 MHz, an output intensity of about 50% of the free running power, a large-scale tuning range of 15 nm and continuous scanning over 4 GHz. In the spatial domain, the laser remains multimode and astigmatic. To show the practical applicability of this system, saturated absorption of a krypton line is demonstrated.     

二极管激光阵列在Talbot外腔中同相模的选择

从理论和实验上对二极管激光阵列在Talbot外腔中的锁相进行了研究。在同相模和异相模近场分布的基础上,利用1维情况下的菲涅耳衍射公式计算了其远场分布。根据同相模和异相模在Talbot腔中的分布特性,采用1/2 Talbot腔并将外腔镜倾斜一个角度a的方法既能选择同相模,又能使模式的功率损耗最小。二极管激光阵列芯片采用CD金刚石材料,“三明治”结构对其进行封装,明显地减小了阵列的“smile”效应。在实验中实现了二极管激光阵列同相模的锁相输出,远场单瓣模的半高全宽为0.11 mm。     

外腔中半导体二极管激光阵列的高阶侧模锁定

 理论分析了外腔较短情况下,宽条半导体二极管激光阵列（LDA）高阶侧模相位锁定的可能性,观察了包含主、旁瓣结构的多侧模远场光强分布。从实验记录结果可以看出,在旁瓣中出现了标志锁相的峰、谷结构,而且该结构的调制度明显高于主瓣中的峰、谷结构的调制度,结果表明：在外腔较短情况下,LDA高阶侧模相位锁定的现象是存在的。     

外腔中半导体二极管激光阵列的高阶侧模锁定

理论分析了外腔较短情况下,宽条半导体二极管激光阵列（LDA）高阶侧模相位锁定的可能性,观察了包含主、旁瓣结构的多侧模远场光强分布。从实验记录结果可以看出,在旁瓣中出现了标志锁相的峰、谷结构,而且该结构的调制度明显高于主瓣中的峰、谷结构的调制度,结果表明：在外腔较短情况下,LDA高阶侧模相位锁定的现象是存在的。     

Achieving single-lobed far-field patterns of broad area laser diode with external cavity feedback

We demonstrate a technique for single transverse mode operation of high-power broad area laser diode (BAL). In the experiment, the HR mirror is used as an external cavity mirror and the grating is used as a wavelength selective component. By tiling the HR mirror and the grating, the number of transverse modes oscillating in the cavity can be limited and the spectral bandwidth of the laser diode can be reduced. A single-lobed near diffraction-limited laser beam with the beam divergence (FWHM) of 0.43°, the spectral line-width of 0.7 nm and the output power of 350 mW are obtained. With the feedback, the power density of the output laser beam is increased 6 times in comparison with the free running.     

双反馈半导体激光器的混沌特性研究

实验利用双反馈半导体激光器获得了关联维数为3.8的高维混沌光.同时对比分析了双反馈与单反馈两种不同模式产生混沌的区别.结果表明：在反馈强度均为-26 dB时,双反馈产生混沌的关联维数高于单反馈产生混沌的关联维数2.6;双反馈可获得带宽为11 GHz的混沌光,为单反馈产生混沌带宽5.5 GHz的两倍.当双反馈的两个外腔长度不相等时,混沌的自相关曲线能很好的隐藏外腔长度信息,可提高混沌通信的保密性. 关键词： 双反馈 半导体激光器 混沌 带宽