射频远红外波导自由电子激光器的新特性

将射频调制的超短脉冲电子束理想化为一系列δ时间函数,提出了用波导本征模展开的方法计算波导自由电子激光器中超短脉冲电子束的相干同步辐射.结果发现当谐振频率等于直线加速器射频的整数倍时,辐射模式表现为”纯”的波导本征模另外分析了超短脉冲在矩形波导中相干发射的频率特性和滑移问题,最后推导了有一定脉宽的矩形脉冲对辐射波的增益解析式.     

用反向渐变波导提高远红外自由电子激光器效率

在高效率和低电流小信号范围内,理论地分析了用反向渐变波导提高远红外波导自由电子激光器(FIR-FEL)效率的机理.并用单粒子模型进行了一维数值模拟,得到了令人鼓舞的结果.     

射频远红外波导自由电子激光器的新特性

提出了用波导本征模展开的方法计算射频调制的短脉冲电子束在矩形波导中的自发辐射。模展开系数决定了辐射进入TE0n模的功率。将短脉冲理想化为时间上的d函数,可以发现当辐射频率正好等于用来调制电子束的射频的整数倍时,辐射模式表现为“纯”的波导本征模,此时辐射功率最强。用此方法估算了设计中的上海远红外波导自由电子激光器的辐射功率。     

射频远红外波导自由电子激光器的新特性

 提出了用波导本征模展开的方法计算射频调制的短脉冲电子束在矩形波导中的自发辐射。模展开系数决定了辐射进入TE_0n模的功率。将短脉冲理想化为时间上的d函数,可以发现当辐射频率正好等于用来调制电子束的射频的整数倍时,辐射模式表现为“纯”的波导本征模,此时辐射功率最强。用此方法估算了设计中的上海远红外波导自由电子激光器的辐射功率。     

远红外波导自由电子激光器的新性能

提出了用波导本征模展开的方法计算射频调制的短脉冲电子束在矩形波导中的自发辐射，模展开系数决定了辐射进入ＴＥ０ｎ模的功率，将短脉冲理想化为时间上的δ函数，可以发现辐射频率正好等于用来调制电子束的射频的整数倍时，辐射模式表现为“纯”的波导本征模，此时辐射功率最强，用此方法估算了设计中的上海远外波导出自由电子激光器的辐射功率。     

射频激励层叠式波导CO2激光器

提出一种射频激励层叠式波导ＣＯ２激光器技术，在两个波导空间尺寸均为１×１４．５×２００ｍｍ３、射频电源频率为９９ＭＨｚ的条件下，获得最大输出功率为７５Ｗ、最大电光转换效率为１０．８％的实验结果，并在远场得到单峰分布的一维压窄光斑     

环形光纤激光器中的半导体光波导调制器

对环形光纤激光器中的半导体光波导调制器进行了理论研究，结果表明，光纤环中的偏振控制器对光的偏振态的控制以及半导体光皮导对光的偏振态的调节构成了激光器的主要调制机理，为环形光纤激光器的自调Ｑ及锁模的新机制提供了理论依据。     

非线性增益和波导结构对半导体激光器的谱线宽度的作用

本文采用半经典理论研究了非线性增益和波导结构对量子相位噪声引起的模式谱线增宽过程的作用,得出谱线宽度不但与线性增益而且与三阶增益有关,并且都受到波导结构的制书。从而提出新的谱线增宽因子和与功率无关的线宽的新机制。 关键词：     

平行耦合腔波导对半导体激光器谱线宽度的控制作用

本文详细分析了平行耦合腔波导对谱线增宽因子的作用,得出在弱耦合和两腔内涨落互不相关的条件下,可以调节波导参数使增宽因子趋于零,从而使谱线宽度降低一个数量级以上,并讨论了耦合腔波导结构的近场和远场分布以及同相和反相模式的选择过程. 关键词：     

Self-consistent simulation on the modal gain of graded-index separate-confinement-heterostructure quantum-well lasers

The effective guide index directly causes the mutual influences in determining the complex refractive index of quantum well and the complex propagation constant of a guided mode. In this paper, self-consistent model (SCM) working on both density matrix theory and transfer matrix method is applied to investigate the modal gain of AlGaAs/GaAs graded-index separate-confinement-heterostructure single quantum-well (GRIN-SCH-SQW) lasers. Based on SCM, the simulated modal gain spectrum shows good agreement with the experimental result. Although varying with the thickness of SCH region or aluminum mole fraction, the percentage change of optical gain is much smaller than that of optical confinement factor. On the other hand, thin well width of QW results in a relative high optical gain but poor optical field confinement. Such opposing effects tend to balance each other and cause the modal gain almost insensitive to the well width change before 60 Å. Further increase of well thickness, the percentage change of optical gain is obviously larger than that of optical confinement factor. Therefore the optical gain becomes the dominant parameter that directly decreases the magnitude of modal gain.     

Effects of transverse mode coupling and optical confinement factor on gallium-nitride based laser diode

We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm thick n-GaN substrate layer, the maximum optical confinement factor was found to be corresponding to the 5^th order transverse mode, the so-called lasing mode. Moreover, the value of the maximum confinement factor varies periodically when increasing the n-side GaN layer thickness, which simultaneously changes and increases the oscillation mode order of the GaN LD caused by the effects of mode coupling. The effects of the thickness and the average composition of Al in the AlGaN/GaN superlat.tice on the optical confinement factor are also presented. Finally, the mode coupling and optimization of the layers in the GaN-based LD are discussed.     

Direct modulation and optical confinement factor modulation of semiconductor lasers

A method for modulation of semiconductor lasers is demonstrated. The method is based on the modulation of the optical confinement factor. Using this method an enhanced—3-dB bandwidth is observed in agreement with the small signal rate equation analysis. A modulation response that drops at high frequencies slower than the conventional direct current modulation response is achieved. This supports the theoretical predictions, showing an intrinsic 1/f decay rate for the optical confinement factor modulation scheme versus an intrinsic 1/f² decay for direct modulation.     

Direct modulation and optical confinement factor modulation of semiconductor lasers

Abstract

A method for modulation of semiconductor lasers is demonstrated. The method is based on the modulation of the optical confinement factor. Using this method an enhanced—3-dB bandwidth is observed in agreement with the small signal rate equation analysis. A modulation response that drops at high frequencies slower than the conventional direct current modulation response is achieved. This supports the theoretical predictions, showing an intrinsic 1/f decay rate for the optical confinement factor modulation scheme versus an intrinsic 1/f² decay for direct modulation.     

Compensating for birefringence in cylindrical active elements of solid-body lasers

We discuss a new method of compensation of thermally induced birefringence in cylindrical active elements of solid-body lasers; the method is based on the simultaneous use of two active elements with sign-opposite temperature gradients in the transverse direction. Basic features of the method are shown and schemes of its practical implementation are considered. To whom correspondence should be addressed. D. F. Ustinov Baltika State Technical University “VOENMEKH”, 1, 1st Krasnoarmeiskaya Str., St. Petersburg, 198005, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 573–577, July–August, 1999.     

Improving the efficiency of certain optically pumped lasers

It is shown that for certain optically excited symmetric top molecules which lase in the far-infrared that it is possible to increase their lasing efficiency through resonant pumping of the higher k quantum number transitions which have increased statistical weights due to increased molecular symmetry.     

光纤环形外腔半导体激光器频偏特性研究

本文给出了在环形光纤外腔光反馈之下半导体激光器频偏特性的小信号分析理论.分析表明,尤其在千兆赫以下的调制频段中,耦合腔相移、内外腔光耦合强度及内外腔光场相位失谐对频偏功率比均有显著影响.可望用作强度调制直接检测高速率、长距离光纤通信系统中的光源.     

Stochastic and coherence resonance in lasers: homoclinic chaos and polarization bistability

We report Stochastic Resonance and Coherence Resonance phenomena in experiments using CO₂ lasers. First, we consider a polarized laser with feedback; for suitable feedback parameters, the laser intensity undergoes homoclinic chaos consisting in the return to a saddle focus, where noise controls the permanence time around the saddle. Second, we discuss a quasi-isotropic laser where noise induces switching between two intensity components with mutually orthogonal polarization.     

强激光反射镜基体材料的热畸变特性有限元分析

 利用有限元方法数值模拟了单晶硅（Si）、铜（Cu）、钨(W)、氧化铍(BeO)等镜体材料的热畸变特性。结果表明：当入射激光功率为2 kW、镜面反射率为93%、光斑直径为17 mm、激光照射时间为10 s时,四种材料基板的中心最大热变形分别为0.984,3.32,1.55,1.88 μm。相比之下,Si镜的热变形最小,是比较理想的镜体材料;Cu镜的热变形最大;W和BeO两种材料的镜热变形介于Si镜和Cu镜之间,具有较高的强度和硬度,抗破坏能力较强。     

强激光反射镜基体材料的热畸变特性有限元分析

利用有限元方法数值模拟了单晶硅（Si）、铜（Cu）、钨(W)、氧化铍(BeO)等镜体材料的热畸变特性。结果表明：当入射激光功率为2 kW、镜面反射率为93%、光斑直径为17 mm、激光照射时间为10 s时,四种材料基板的中心最大热变形分别为0.984,3.32,1.55,1.88 μm。相比之下,Si镜的热变形最小,是比较理想的镜体材料;Cu镜的热变形最大;W和BeO两种材料的镜热变形介于Si镜和Cu镜之间,具有较高的强度和硬度,抗破坏能力较强。