脉冲主动锁模和主被动锁模激光器

本文报导了脉冲式主动、主被动锁模磷酸盐玻璃振荡器的特性.主动锁模的脉冲宽度为200微微秒左右,输出性能比较稳定.对于输出脉宽为7微微秒左右的主被动锁模,出现卫星脉冲的几率与调制器的调制系数有关.使用不同的腔内标准具能产生30微微秒和70微微秒的脉冲,没有观察到卫星脉冲.主被动锁模的性能比被动锁模有所提高.     

Measurement of reflectivity of butt-joint active-passive interfaces in integrated extended cavity lasers

A method and measurement results are presented for the determination of the reflectivity of butt-joint active-passive interfaces in a series of extended cavity Fabry-Pe/spl acute/rot lasers. The method is based on the analysis of subthreshold laser spectra. The small reflections at the two intracavity active-passive interfaces modify the mode structure of the laser. By fitting the calculated subthreshold mode structure to the recorded data, values of the reflectivities are extracted. An average value of 9.10/sup -5/ has been determined. The value of the reflectivity of those interfaces is relevant for photonic integrated circuits and particularly integrated mode-locked lasers.     

高功率宽带调谐皮秒激光器

用ＹＡＧ主被动碰撞锁模激光器泵浦光学参量发生器和放大器，并进行倍频，产生了脉冲宽度１０ＰＳ、峰质功率ＭＷ量级的红外－可见－紫外宽带连续调谐的皮秒激光脉冲。     

用于激光等离子体诊断的主被动锁模染料激光系统

本文叙述了作为激光等离子体微微秒照相脉冲光源用的染料激光系统。它采用主-被动锁模相结合的染料激光脉冲与碘激光脉冲同步工作。染料激光脉冲相对于碘激光脉冲的到达时间可以预先选择,同步精度为200微微秒。在靶照射实验中,两个脉冲的同步成功率为76％。     

电光-GaAs主被动双调Q激光特性研究

为了研究调Q激光脉冲波型的对称性,利用电光调制和GaAs半导体饱和吸收体,实现了电光-GaAs主被动双调Q激光运转。与单一电光主动调Q或GaAs被动调Q激光对比,双调Q激光的脉冲宽度更窄、脉冲波型更对称,其脉冲宽度的压缩比大于40%。定义了一个对称因子来描述脉冲波型的对称性,对称性的改善优于10%。在平面波近似下,给出了双调Q激光运转的耦合方程组,数值求解方程组得到的理论值与实验结果相符。     

Realization and modeling of a 27-GHz integrated passively mode-locked ring laser

We present a realization and the modeling of a 27-GHz integrated extended cavity ring laser that is passively mode-locked. The mode-locked ring laser is fabricated with active-passive integration. Experimental results show that internal reflections are the major factor affecting operation stability. Continuous-wave, self-pulsating, and in small windows of operation mode-locked regimes have been observed. Similar regimes have been observed in our bidirectional laser model. This model describes the semiconductor amplifier and the saturable absorber using rate equations. Our experimental and theoretical results are compared and discussed.     

Wavelength tuning analysis and spectral characteristics ofthree-section DBR lasers

A theoretical model for the design of three-section distributed Bragg reflector (DBR) lasers using the transfer matrix method is presented. The oscillation parameters, the tuning behavior, and the linewidth are derived. The effect of a discontinuity of the waveguide at the active-passive interface is accounted for by using scattering matrix parameters, easily combined with the transfer matrix method. The influence of such an interface is studied and the importance of optical losses at this point is discussed     

简并四波混频用于饱和吸收体的性能比较

本文报道了几种可用于钕激光锁模的快速饱和吸收体中ps光脉冲的简并四波混频,利用信号光波的强度和时间分辩特性,比较了Kodak 9740,9860、五甲川和两种新染料HIR1301,HIR1302的性能,首次给出了新染料的弛豫时间,并比较了这些染料直接用于主被动锁模激光器时输出光脉冲的性能。     

以多掺杂YAG为调Q元件的主被动锁模激光器

报道一种新型主被动锁模激光器,它的饱和吸收体是一种新型多掺杂YAG晶体。以C轴YLF为工作物质时,得到的输出序列脉冲的平均能量为5.64mJ,能量起伏小于±5％,所占几率为96.9％,脉冲半宽平均为1.45ns;以Nd:YAG为工作物质时,输出序列脉冲能量平均为6.79mJ,能量起伏小于±4％,所占几率为96％,脉冲半宽平均为270ps。     

Electrical characteristics of the interface between laser-recrystallized polycrystalline silicon and the underlying insulator

The effects of fabrication processes on the electrical characteristics of the interface between a thin laser-recrystallized polysilicon film and the underlying oxide insulator in a silicon-on-insulator (SOI) structure have been investigated. It has been found that an underlying oxide layer thermally grown in an oxygen and HC1 ambient resulted in the lowest fixed-oxide charge density. A double-layered 6 nm LPCVD nitride and a 10 nm plasma CVD oxide encapsulating structure deposited on the polysilicon film prior to laser recrystallization was also found to be effective in reducing the charge at the back interface. Oxide charge densities as low as 3 × 10¹¹cm^-2have been obtained, compared to the otherwise typical values of 1 to 2 × 10¹²cm^-2.     

利用二次谐波产生研究Al2O3/Al(111)表面的动力学变化

主要介绍了当激光入射到单晶金属Al2O3／Al(111)表面时将发生二次谐波产生(SHG)现象的实验装置和实验方法,利用该装置可以研究SHG和从Al2O3／Al(111)表面反射的SHG在空间各向异性的变化情况,从而可以探测Al2O3／Al(111)表面结构对称性。实验中发现,当脉冲激光功率在2×106 W／cm2-9．6×106W／cm2范围内变化时,没有检测到SHG信号的各向异性变化;当使用P-极化泵浦激光时,发现Al2O3／Al(111)样品绕法线旋转360度时,P-极化的SHG信号在空间三个方向上呈现最大值相等;当使用脉冲强度为12×100 W／cm2的1064 nm P-极化泵浦激光时, Al2O3／Al(111)表面被损坏,损坏后的表面其SHG信号并不呈现对称的各向异性变化,当使用脉冲强度为11×106W／cm2的1064 nm P-极化泵浦激光时产生表面退火现象,从退火表面所产生的反射532 nm P-极化SHG信号中发现,SHG信号呈现衰减的各向异性成分。     

单光子探测器SPICE模型及主被动混合淬灭电路研究

单光子雪崩光电二极管(SPAD)是目前激光测距领域常见的单光子探测器。针对SPAD在单光子探测应用中的高速淬灭问题,设计了一种可以快速淬灭雪崩电流、缩短偏置电压恢复时间的主被动混合淬灭电路。根据实际使用的SPAD器件相关性能参数,建立了SPAD的SPICE模型;使用被动淬灭电路对该模型进行验证,证实了该模型的准确性和实用性;结合SPICE模型,通过计算机仿真技术对主被动混合淬灭电路进行了参数调整和功能验证。结果表明,所设计电路的淬灭时间和恢复时间分别达到200和400ps,满足单光子激光测距的应用需求。该混合淬灭电路结构简单,可以用于全集成单光子阵列探测器的相关研究。     

激光照射下金电极/溶液界面的电子转移行为

用伏安法初步研究了激光照射下金电极／溶液界面的电子转移行为。对Ｆｅ＾３＋／Ｆｅ＾２＋,激光照射引起氧化还原峰增高并向阳极方向移动,氧化还原电位负向变化,激光功率对电流－电位曲线的平移幅度具有明显影响。激光照射对抗坏血酸的电子转移作用更显著,电流峰高增加了２．０２倍,过电位减少了０．２５Ｖ。激光能量对电极表面的作用及界面溶液层的影响加速了电子转移并提高了电极反应的灵敏度。     

主被动雷达复合导引头信息融合技术研究

针对主被动雷达复合导引头,研究了基于序贯扩展Kalman滤波的信息融合算法。利用主被动雷达复合导引头对目标角误差进行观测,将匹配后的测量角度进行最优加权,进而以角度信息作为量测,估计目标的运动信息。通过试验验证,基于主被动雷达信息融合状态估计比仅依赖主动雷达观测量的状态估计稳态误差小,且滤波器收敛速度更快。     

Write pulse Generator for 16x DVD recording with symmetric CMOS inverter ring oscillator

This paper reports the design and measurement results of a write pulse generator IC for rewritable CD and DVD disk drives implemented in a standard digital 0.35 /spl mu/m CMOS technology. The chip is the interface between a processor and a laser driver. It provides accurate timing signals to the laser driver via a four-level differential current interface. Transitions between current levels are programmable with 149 ps resolution at a data rate of 420 Mb/s, corresponding to 16x DVD write speed. The chip includes a digital core managing the different write strategies, a CMOS serial interface to the processor for programming, a low power, low phase noise, 64-phase ring voltage-controlled oscillator (VCO) based on CMOS inverters, a phase-locked loop (PLL) locking the VCO to the system clock, and a current interface to the laser driver. The PLL phase noise is -144 dBc/Hz at 10 MHz offset from the 105 MHz carrier. At this frequency, the rms jitter is 1.1 ps with 0.8 mA VCO core supply current. The chip is fully ESD protected.     

交叉眼技术对主被动复合单脉冲雷达测角的干扰效果分析

交叉眼技术是一种通过相干多点辐射源诱使单脉冲雷达测角偏差的电子对抗技术。面对攻防双方激烈对抗的复杂电磁环境,采用主被动复合单脉冲雷达测角是现代末制导雷达提高抗干扰能力的发展趋势之一。该文以主被动复合单脉冲雷达为干扰对象,建立了交叉眼干扰数学模型,通过对比交叉眼技术对抗主动单脉冲测角和被动单脉冲测角的干扰效果,揭示了交叉眼技术对主被动复合单脉冲雷达的影响机理。该研究成果可为干扰与抗干扰的合理应用提供理论规律和仿真数据。      

Ni基合金/45#钢宽、窄带熔覆Co基合金的组织

利用 5kWCO2 激光器在Ni基铸造高温合金 4 5 #钢基体上宽带、窄带激光熔覆了H¨ogan¨as钴基合金 ,制备了无缺陷的涂层。用金相显微镜、扫描电镜和X射线衍射仪对比分析了熔覆层的显微组织特征和相结构。结果显示 ,熔覆层均为由初生相γ Co枝晶和γ Co +Cr2 3C6 共晶组成。宽带熔覆层界面为垂直于界面生长 ,窄带熔覆层界面结晶方向受热流控制 ,为多方向结晶。 4 5 #钢熔覆层界面具有明显的白亮过渡层且宽带熔覆比窄带宽 ;Ni基合金熔覆层界面区很宽且不规则 ,无白亮色过渡层。沿熔覆层中心线的纵截面取样可见平行生长的枝晶     

Improvement of GaAs/AlGaAs quantum well laser diodes by rapid thermal annealing

Post-growth annealing is shown to improve the laser diode quality of GaAs/AlGaAs graded-index separate confinement heterostructure quantum well laser diode structures grown at a nonoptimal substrate temperature lower than 680°C by molecular beam epitaxy. Reduction by a factor of up to three in the threshold current was accompanied by a reduction in the interface trap density. The reduced threshold current is still higher than that of laser diodes grown at the optimal temperatures which are between 680 and 695°C. The improvement in laser diode performance is ascribed to the reduction of interface nonradiative recombination centers.     

激光剥离GaN/Al2O3材料温度分布的解析分析

分析了脉冲激光作用下GaN的衬底剥离过程。利用简化的一维模型，给出一种比较直观的脉冲激光辐照下GaN／Al2O3材料温度分布的解析形式，得到了分界面温度和脉冲宽度的关系。表明，单脉冲作用下分界面的温度与加热时间的平方根成正比，并得出脉冲过后随着深度变化温度梯度的分布。在连续脉冲作用时，分界面的温度呈锯齿状不断升高。     

无钎剂激光喷射植球工艺的研究

为了研究在氮气保护条件下,无钎剂激光喷射植球工艺参数对凸点剥离强度的影响,对激光电流、激光脉冲时间和凸点剥离强度的关系进行了试验,得出了激光脉冲时间一定时,剥离强度随激光电流的增加而降低;激光电流一定时,剥离强度随脉冲时间的增加而增加的结果;同时借助扫描电镜和能谱分析,对凸点(Sn63Pb37)/焊盘(Au/Ni/Cu镀层)界面的组织形貌及相组成进行了分析.结果表明,在保证凸点外观质量的前提下,大激光电流、短激光脉冲时间时凸点剥离强度较低,小激光电流、长激光脉冲时间时凸点剥离强度较高;在现试验条件下,钎料球能很好地润湿焊盘并在凸点/焊盘界面处形成了连续的AuSn4金属间化合物层.