激光二极管点火机理研究

通过理论分析、实验和数值计算研究了激光二极管点火的热作用机理，分析了点火的临界值及影响因素。一般情况下，含能材料的激光二极管点火机理主要表现为热作用；激光功率密度是影响点火的重要因素。     

激光二极管阵列侧面抽运棒状激光器轴向热效应分析

对激光二极管阵列侧面抽运棒状激光晶体热效应进行了理论分析和数值模拟.采用有限元方法模拟了棒状激光晶体内部三维温度场分布和热应力分布,得出激光晶体内抽运光强和温度随抽运距离的变化规律,并得出了激光晶体轴向温度分布是不均匀的,而是与激光二极管阵列的占空比有关.为减小激光系统的热效应提供了理论依据.     

连续运转Yb:YAG板条激光器的双波长放大特性

报道了一种室温条件下工作的高功率激光二极管(LD)端面抽运Yb:YAG板条双波长激光放大器,稳定的双波长运转在1029.6,1031.5nm。基于Yb:YAG宽带荧光特性,建立了双波长放大模型,通过数值模拟研究了不同抽运条件下激光光谱放大输出特性。通过940nm激光二极管双端抽运Yb:YAG晶体,拥有双波长光谱的种子光从晶体一端注入并进行放大。实验结果表明,在1.18kW注入时获得了6.56kW的双波长连续激光输出,与数值模拟结果相吻合。双波长激光放大理论和实验研究为进一步实现高功率光谱合成等应用奠定了基础。     

Nd:GdVO4和Nd:YAG全固态激光器输出特性的比较

文中基于Nd：GdVO4晶体的能级结构和速率方程理论，对激光二极管端面抽运Nd：Gd．VO4固体激光器的输入输出特性参数进行了理论研究。通过数值计算得到了其振荡光的光斑与抽运光斑的匹配程度、增益介质的长度、腔内固有损耗和输出镜透过率的最佳值，并通过与激光二极管抽运Nd：YAG固体激光器的输出特性进行比较，获得了在相同条件下Nd：GdVO4晶体的输出特性优于Nd：YAG晶体的高功率端面抽运的全固态激光器，其理论值与实验结果一致。     

Nd∶GdVO4 和Nd∶YAG全固态激光器输出特性的比较

文中基于Nd∶GdVO4晶体的能级结构和速率方程理论,对激光二极管端面抽运Nd∶Gd-VO4固体激光器的输入输出特性参数进行了理论研究。通过数值计算得到了其振荡光的光斑与抽运光斑的匹配程度、增益介质的长度、腔内固有损耗和输出镜透过率的最佳值,并通过与激光二极管抽运Nd∶YAG固体激光器的输出特性进行比较,获得了在相同条件下Nd∶GdVO4晶体的输出特性优于Nd∶YAG晶体的高功率端面抽运的全固态激光器,其理论值与实验结果一致。     

以单纵模振荡的InGaAsP激光二极管的时间相干特性

激光二极管的时间相干性在相干光学传递技术和单模光纤传感器技术中都占有很重要的地位。然而以往着重研究的都是采用GaAlAs激光二极管的多模振荡。正如其他文献中提到的那样,多模运转中观察到的相干性,不仅反映了激光二极管固有的线宽而且反映了激光二极管材料对纵模分布的影响。为了研究激光二极管作为相干光源的可能性,必须弄清激光二极管单模振荡的相干特性,即激光二极管固有的相干性。此外,InGaAsP激光二极管发射的波长为1.30μm和1.55μm,由于二氧化硅光导纤维对这两种波长具有较低的损耗与最小的色散,所以,InGaAsP激光二极管是一种比GaAlAs激光二极管更好的相干光源。     

Nd:YVO4和Nd:YAG全固态激光器输出特性的比较分析

基于Nd：YVO4晶体的能级结构和速率厅程，对激光二极管端面抽运Nd：YVO4同体激光器的输入输出特性参量进行了理论研究。并通过数值计算得到了其振荡光的光斑与抽运光斑的匹配程度、增益介质的长度、腔内同有损耗和输出镜透过率的最佳值，并通过与激光二极管抽运Nd：YAG同体激光器的输出特性进行比较，获得了在相同条件下Nd：YVO4晶体的输出特性优于Nd：YAG晶体的高功率端面抽运的全同态激光器，其理论值与实验结果相吻合。     

V型槽侧面抽运的光学耦合模型的研究

V型槽侧面耦合是目前双包层光纤抽运光耦合的方法之一。本文提出了一种二透镜光学系统的耦合模型，并利用几何光学的ABCD矩阵分析和计算了透镜焦距与激光二极管阵列（LD—Arrays），透镜，双包层光纤（DCF）三者之间间距的关系，同时通过计算确定了V型槽所开的最佳角度。通过数值模拟计算发现透镜焦距的选取在很小范围内会引起两透镜间距的剧烈变化而且激光二极管与透镜的间距以及两透镜间的间距主要取决于靠近激光二极管那个透镜的焦距大小。本文的分析和计算对V型槽侧面抽运的光学耦合系统中透镜焦距的选取以及LD，透镜，DCF三者之间间距的设置的最优化提供了理论指导。     

Nd∶GdVO4 和Nd∶YAG全固态激光器输出特性的比较

文中基于Nd∶GdVO4 晶体的能级结构和速率方程理论,对激光二极管端面抽运Nd∶Gd2 VO4 固体激光器的输入输出特性参数进行了理论研究。通过数值计算得到了其振荡光的光斑与抽运光斑的匹配程度、增益介质的长度、腔内固有损耗和输出镜透过率的最佳值,并通过与激光二极管抽运Nd∶YAG固体激光器的输出特性进行比较,获得了在相同条件下Nd∶GdVO4晶体的输出特性优于Nd∶YAG晶体的高功率端面抽运的全固态激光器,其理论值与实验结果一致。     

激光二极管泵浦的Nd~（3＋）：YVO_4内脏倍频激光器的稳态、反相态及混沌态输出研究

报道了激光二极管泵浦、内腔倍频、各向异性晶体Ｎｄ３＋：ＹＶＯ４激光器的输出特性．包括稳态、反相态以及混沌态研究结果，并根据理论模型对这些运转状态进行数值分析，理论计算与实验结果十分吻合。     

频率对PIN限幅器微波脉冲热损毁效应的影响

采用数值仿真和理论分析相结合的方法研究了频率对PIN（positive-intrinsic-negative）限幅器微波脉冲热损毁效应的影响.研究发现,在相同脉冲宽度情况下,PIN限幅器微波脉冲热损毁功率阈值随频率的升高而降低,由于在一定功率下虽然频率与微波脉冲能量无关,但是在相同脉冲宽度情况下,PIN管阻抗周期性增大的次数随着频率的升高而增多,使得PIN管平均阻抗增大,实际吸收能量增多.该规律对全面评估PIN限幅器的微波脉冲防护能力具有重要的意义.     

Numerical analysis of a double avalanche region IMPATT diode on the basis of nonlinear model

The analysis of the n⁺pvnp⁺ avalanche diode structure has been realized on the basis of the nonlinear model. This type of the diode that was named as double avalanche region (DAR) IMPATT diode includes two avalanche regions inside the diode. The phase delay which was produced by means of the two avalanche regions and the drift region v is sufficient to obtain the negative resistance for the wide frequency band. The numerical model that is used for the analysis of the various diode structures includes all principal features of the physical phenomena inside the semiconductor structure. The admittance characteristics of the DAR diode were analyzed in very wide frequency band. The obtained results contradict to the before performed analysis on basis of the approximate models and show that only diode with a sufficiently short drift region can produce active power in some frequency bands.     

Estimation of the linewidth enhancement factor for a PbCdS diodelaser

An estimation of the linewidth enhancement factor α for a PbCdS diode laser is reported. The measurement method, which is an extension of an earlier procedure involving studies of mode spectra, was devised particularly for this lead-salt diode laser of very low output power. A quite low α of 1.3 was obtained, well below the values for other types of diode lasers     

Effect of the junction capacitance variation and a small inductance on the switching time of a tunnel diode

Analytic closed-form switching time expressions of a tunnel diode are derived considering the voltage dependence of the diode junction capacitance and a small inductance that is always associated with the trigger circuit. The contribution due to the capacitance variation and that due to the inductance are expressed by a separate term added in the usual switching time results.     

On the use of a backward diode in parallel with a tunnel diode in pulse shaping circuits

The transient respose of a system having a parallel combination of a tunnel diode and a backward diode is investigated. The results show that such a system can be used for improving the top of the output pulse with some sacrifice of the switching speed.     

Measurement of the Residual Modal Reflectivity of AR Coating on a SLD

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Measurement of the mobility and concentration of charge carriers in a Gunn gallium-arsenide diode using a near-field microwave microscope

The results of local contactless measurement of the dependence of conductivity in a Gunn diode on the external electrical bias are presented. The technique of local determination of the charge-carrier concentration and mobility in a commercially produced chip Gunn diode for various values of the supply voltage is proposed.     

The resonant terahertz response of a slot diode with a two-dimensional electron channel

The terahertz response of a slot diode with a two-dimensional electron channel is calculated on the basis of the first principles of electromagnetism. It is shown that all characteristic electromagnetic lengths (scattering, absorption, and extinction lengths), as well as the impedance of the diode, exhibit resonances at plasmon excitation frequencies in the channel. The fundamental resonance behaves similarly to the current resonance in an RLC circuit. It has been concluded that, even at room temperature, a slot diode with a two-dimensional electron channel provides a resonant circuit at terahertz frequencies that couples effectively to external electromagnetic radiation with a loaded Q-factor exceeding unity. The diode resistance may be measured from contactless measurements of the characteristic electromagnetic lengths of the diode.     

Evaluation of the diffraction losses for a single-element diodelaser transmitter in a free-space optical link

The losses in an optical link using a diode laser transmitter are calculated as a function of the size of the transmitter lens and the degree of astigmatic wavefront aberration present in the diode laser output. Unlike previous treatments, this treatment accounts for the correlation between the intensity distribution and wavefront aberrations in the calculation of the Strehl intensity by modeling the laser output as a truncated astigmatic Gaussian beam. Families of curves showing the Strehl intensity versus astigmatism at various truncations are presented. The results can be generally applied in calculating the link losses for any diode laser transmitter whose astigmatic Seidel coefficient or root-mean-square wavefront aberration has been measured. Examples using wavefront measurements of the output of single-element gain-guided and index-guided diode lasers are also presented