非稳腔的热稳定性分析

本文以非稳腔的放大率为特征量,讨论了非稳腔的热稳问题,求出了非稳腔热稳条件的解析解。     

非稳腔-稳腔混合腔失调特性理论研究

非稳腔-稳腔混合腔的失调特性得到了理论上的研究.当调节混合腔的输出耦合镜几何参数改变时,通过Fox-Li数值迭代法计算其基横模的损耗来研究腔的失调特性.发现混合腔在稳腔方向上不易失调;混合腔的不稳定主要来自于非稳腔方向,且主要来自于输出耦合镜在非稳腔平面内的转动,或者垂直于光轴的平移;偏轴非稳腔要比对称非稳腔稳定.利用混合腔中非稳腔方向易失调的特性,可以设计调Q方案.在正支共焦偏轴非稳腔-稳腔混合腔中应用声光调制器在非稳腔平面内实现声光调Q的可行性,得到了理论的证明.     

圆对称非稳腔的光束发散度问题

本文研究了非稳腔激光束发散度与腔的放大倍数的关系,并提出了非稳腔设计的原则。     

高斯反射率镜谐振腔的非稳条件

根据非稳腔的横向放大率和点源位置必须为实数,求出了高斯反射率镜(GRM)谐振腔的非稳条件。并指出高斯反射率镜不可能构成非稳腔。     

非稳腔运转的准分子激光器

设计了一正支望远镜非稳腔准分子激光器，与稳定腔相比，非稳腔激光的发散角垂直方向缩小了五倍，水平方向缩小了十倍。     

非稳腔运转的准分子激光器

设计了一正支望远镜型非稳腔准分子激光器,与稳定腔相比,非稳腔激光的发散角垂直方向缩小了五倍,水平方向缩小了十倍。     

高斯变反镜改善板条激光器光束质量的研究

在实验中对比研究了稳腔和高斯变反镜非稳腔两种腔型。采用尺寸为66.7 mm×11 mm×1.7 mm板条Nd∶YAG增益介质,泵浦功率860 W条件下,稳腔获得196 W的激光输出,Mx2=2.47,My2=38.6;高斯变反镜非稳腔获得102 W激光输出,Mx2=2.34,My2=6.48。实验结果表明高斯变反镜非稳腔明显改善了板条激光器宽度方向的激光输出光束质量。     

氯化氙激光光束质量对H_2中受激喇曼散射转换效率的影响

比较了稳腔、平面平行腔及非稳腔氯化氙激光器在高压氢气中受激喇曼散射的特性.采用环状光阑截取非稳腔激光输出中光束质量最佳部分,在40mJ泵浦能量下,获得喇曼光子转换效率大于90%.     

离轴非稳腔导引光多光束干涉与远场图样研究

研究光腔内导引光的往返振荡物理过程与传播特性有助于理解、判断光腔的准直失调状态。离轴非稳腔作为一种兼具高提取效率与高光束质量的混合非稳腔,调腔导引光在离轴非稳腔中的振荡物理过程研究鲜有报道。通过理论计算与实验研究了导引光在离轴非稳腔内的多光束干涉过程及其远场传播特征,在实验中搭建了离轴非稳腔（X方向为平凹稳定腔,Y方向为共焦非稳腔）导引光研究装置,通过凹球面镜小孔注入波长为632.8 nm的基模高斯光束,开展了光腔准直与导引光远场图样研究,实验结果与计算结果吻合较好。计算与实验结果表明：离轴非稳腔的干涉图样与传统共焦非稳腔/稳定腔不同,调腔导引光在腔镜小孔注入处出现椭圆“水滴”状干涉图样,该图样亮度较高,可以用于判断光腔的准直状态。输出导引光的远场光斑在Y方向上是不同振荡阶次的亮核光斑,其中高阶次亮核光斑可用于指示红外激光的远场光斑位置。     

分析非稳腔的几种方法

在《激光原理》非稳腔的教学中,广泛使用由Siegman提出的高斯成像方法,其特点是比较直观,便于理解.但对复杂非稳腔,使用这一方法计算十分繁冗.我们曾首次使用牛顿成像方程递推,对多元件非稳腔给出了公式化描述,使计算大为简化。对非稳腔基模的正则描述首推ABCD矩阵法。本文拟结合《激光原理》教学和光腔设计,对     

Design of aberration-corrected curved-mirror and curved-gratingunstable resonator diode lasers

An algorithm is presented for the design of an unstable optical resonator that supports an arbitrary optical mode. The same algorithm may be applied to the design of curved-mirror and curved-grating resonators, including both distributed Bragg reflector and distributed feedback unstable resonators. The new design formalism produces much simpler formulas than an algorithm previously described by the author. Example resonators are calculated that include hyperbolic-grating resonators with aberration-free diverging-beam modes and a newly proposed device: a parabolic-grating confocal distributed feedback unstable resonator that possesses a collimated output beam     

非稳腔在铜蒸气激光器中的应用

近来,金属蒸气激光器,其中特别是铜蒸气激光器在医学研究和临床、高速照相和同位素分离应用中有很高的使用价值。这类激光器的增益高,反转寿命短,激光脉宽一般为20～30ns。 实验证明靠改变稳定腔参数来提高这类激光器输出的激光的方向性是困难的,需要考虑使用非稳定腔。 图1给出我们设计的望远镜或非稳腔示意图。     

Time resolved beam divergence from a copper vapor laser withunstable resonator

The temporal evolution of the far-field intensity distribution (and hence beam divergence) for the output of a CVL operating with both on-axis and off-axis unstable resonators is investigated in detail. The CVL output pulse consists of several temporally resolved components, where each successive component has lower divergence approaching the diffraction limit. A comprehensive model for the divergence of each temporal component from a CVL operating with a variety of unstable resonators is presented. In this model the resonator controls the output divergence by imposing geometric constraints on the propagation of spontaneous emission on repeated round-trips through the unstable resonator equivalent lensguide. Effects of resonator asymmetry and radial gain variations on the far-field intensity distribution (and hence divergence) are evaluated. Experimental measurements of the temporal evolution of output divergence from a CVL operating with both on-axis and off-axis unstable resonators and for a variety of excitation conditions are also presented. For CVL operation at high pulse repetition frequency the ASE at the start of the laser pulse has an annular profile. This annular gain distribution is found to modify the output far-field intensity distribution of the earlier temporal components of the laser pulse. For on-axis unstable resonators these components are found to have annular far-field intensity distributions, whereas for off-axis unstable resonators they have greatly reduced but anisotropic divergence     

Design of unstable laser resonators with user-defined mode shape

By introducing surface-structured mirrors into stable laser resonators, the generation of user-defined mode profiles and properties has become possible. On a wave-optical basis, we show that there is a general connection between the property of the modes to be phase-conjugated during reflection at the mirrors and their diffraction losses at apertures. This connection makes the design method known for stable resonators with predefined modes unsuitable for the design of such resonators of unstable geometry. An alternative method for the calculation of unstable resonators with user-defined output beam shape is presented and demonstrated by an example design     

环形非稳腔倒向波抑制镜抑制效果的数值模拟

对环形非稳腔激光器做数值计算模拟,给带有倒向波抑制(RWS)镜的环形非稳腔激光器的设计提供了数值参考。通过自洽方程,用Matlab计算带有倒向波抑制镜的环形非稳腔正、倒向波的稳定过程。改变腔长、放大率等参数来计算,发现使用倒向波抑制镜能明显提高正向波的输出,并能抑制倒向波。气体分子的多普勒频移导致正、倒向波的频率变化。频率分开的越小,竞争越大,抑制效果越好,正向波输出功率则有所下降。对于特定的结构,存在最佳的放大率,使正向波的输出最大。计算结果表明,倒向波抑制镜的引入能增大环形非稳腔输出功率。计算结果对实际环形非稳腔的设计十分有用。     

A canonical formulation for analyzing multielement unstable resonators

A simple but general formulation for the unified analysis of many different varieties of unstable optical resonators is obtained by expressing the round-trip Huygens' integral for the resonator in terms of the round-trip paraxial ray matrix. Complicated multielement resonators, ring resonators, and unstable resonators with variable-reflectivity output mirrors are thereby all reduced to a single equivalent collimated-beam diffraction problem. Essential assumptions in the analysis are that all elements in the resonator obey paraxial ray theory and that there is only one significant output coupler or limiting aperture per round trip inside the resonator. The only parameters needed to describe an arbitrary unstable resonator in this formulation are the round-trip magnificationMand either the equivalent Fresnel number Neqor else an equivalent collimated Fresnel numberN_{c} = [2M^{2}/(M^{2} - 1)] N_{eq}, plus for variable-reflectivity mirrors a specification of the mirror reflectivity profile.     

非稳腔的远场光强分布和光束质量

在对远场光强分布分析的基础上,对非稳腔的光束质量作了详细研究。证明了当遮拦比ε→1时,其远场光强是零阶贝塞尔光束分布。对数值计算结果的物理分析表明:用“桶中功率”曲线是评价非稳腔远场光束质量适用的方法。同时,也指出了这种方法的不足之处。     

Lasers with super-Gaussian mirrors

A systematic theoretical and experimental investigation of unstable resonators with variable reflectivity mirrors of a super-Gaussian profile is presented. The validity of a geometrical optics formalism for an algebraic mode calculation is discussed in comparison to the diffraction theory. A new method for the calculation of the output energy by means of a closed-form relationship that accounts for the effects of the transverse mode profile on gain saturation is presented. Various dielectric super-Gaussian mirrors have been fabricated, characterized, and tested in a pulsed Nd:YAG laser. Super-Gaussian resonators can provide even higher output energies than those of traditional unstable resonators and with better beam-focusing properties     

等价光学谐振腔的特性分析

本文同时采用矩阵光学理论及衍射积分理论，详细地分析了在稳定腔及非稳腔情况下，一般多元件谐振腔的等价腔的特性，得到了一些重要结果，并对这些结果进行了细致的讨论．