均匀加宽注入锁定环形激光器的半经典理论—小信号分析

本文用拉姆(Lamb)的半经典理论分析了在小信号情况下均匀加宽注入锁定环形激光器的单模运转问题.     

非激光振转能级对CO_2激光器小信号调制响应的影响

本文以简化的多能级理论模型为出发点,讨论了具有均匀加宽介质的单模CO_2激光器的稳态特性,线性稳定性和小信号腔长调制响应,泵浦调制响应,增益或损耗调制响应,并将其结果与由简单的二能级理论所得的结果进行比较,着重分析了非激光振转能级对上述三种调制响应的影响.     

兰姆下陷

在单模激光器中,当激光跃迁的增益曲线由于多普勒效应或压力效应等原因而产生非均匀加宽时,激光器的输出功率在原子跃迁的中心频率v0处有一极小值,如图所示.我们可以看到:在曲线中央,有一对应于原子跃迁中心频率v0的凹形下陷.这就是“兰姆下陷”. 由于这是一个对称的凹形下陷,因此可以利用光电元件及电子学仪器从单模激光器的输出中获得误差信号,从而稳定激光器的振荡频率.并且,由于兰姆下陷的极小值仅与原子跃迁中心频率有关;在工艺上可以使兰姆下陷中心两侧的斜率较陡,因此,用这种方法可以获得频率稳定性较好(10-9数量级)的激光器.兰姆下…     

XeCl激光器的增益特性

本文根据稳腔均匀加宽激光器的模型,按照激光器的输出功率与小信号增益系数g,恒定的吸收损耗系数a_o,饱和强度I_s,腔长L之间的近似关系式,利用变换输出耦合的方法,对采用紫外预电离的Blumlein快放电激励XeCl激光器的增益进行测量.并讨论了器件的最佳透过率.发现最佳透过率是泵浦功率的函数.     

连续钛宝石激光器最佳输出透射率的测量

在连续钛宝石激光器中，在一定泵浦功率下通过直接测量腔内熔融石英片在不同入射角时的反射耦合输出，得到了激光器的最佳输出透射率。在两个不同的输出透射率条件下，测量激光器的泵浦阈值，经计算求得了不同泵浦功率下激光器最佳输出透射率的理论值。对浓度不同的钛宝石棒均作了测量和计算，测量值与理论值基本符合。     

渡越加宽对非均匀加宽线型和线宽的影响

本文讨论了流动和化学激光器的非均匀加宽介质吸收或发射谱线中的渡越加宽效应;导出了线型函数的积分表示;并在高速流的条件下得到中心频率处线型函数近似表示式;在等效线宽近似下得到渡越加宽使得线宽的增加随流速加快的关系式;并用激光谐振腔菲涅尔数讨论了渡越加宽有意义的条件。     

低气压超声速连续波HF化学激光器的介质光抽取效率

根据气流与化学激光的“对流－非平衡交叉驰豫”的理论,对于气流介质的湍流和层流混合两类流动模型,数值模拟计算了低气压超声速连续波ＨＦ化学激光器的介质光抽取效率,并与均匀加宽连续波气体激光器的情况相比较。     

基于非线性偏振旋转效应的多波长光纤激光器

多波长光纤激光器是未来波分复用光通信系统的理想光源,提出和展示了一个基于非线性偏振旋转效应的多波长光纤激光器,非线性偏振旋转诱导的强度相关非均匀损耗能有效地抑制均匀加宽增益介质掺铒光纤中的模式竞争,从而使光纤激光器在室温下产生稳定的多波长输出,实验实现了最多18个波长的多波长输出.另外,此激光器没有使用传统的滤波器,而是在激光腔内插入一段保偏光纤,保偏光纤与偏振相关隔离器构成一等效Lyot双折射光纤周期性滤波器.利用这种在线型的双折射光纤滤波器简化了光纤激光器的结构,使它更易于集成.还实验研究了多波长输出随抽运功率的演化,发现抽运功率对多波长的均匀性影响很大.     

后腔镜对掺镱双包层光纤激光器输出特性影响研究

使用国产掺镱双包层光纤搭建了双包层激光器实验系统.将透射率不同的反射镜作为后腔镜进行了激光器输出激光光谱和功率测量.根据激光器数学模型和增益理论,分析了实验中后腔镜参量对激光器输出特性的影响,并深入讨论了后腔镜透射率与激光器输出波长之间的关系.实验表明：后腔镜与激光器输出激光功率和波长紧密联系,通过调节后腔镜的透射率可以优化系统的输出激光特性.     

基于混合加宽的宽带激光脉冲放大的物理模型

建立了宽带激光脉冲放大的物理模型.模型引入交叉弛豫时间表征不同频率响应下反转粒子与激光作用后重新形成分布的快慢，模型考虑的整体非均匀加宽、局部均匀加宽的混合加宽机理弥补了现有放大模型仅考虑均匀加宽的不足.基于此物理模型，开发了宽带激光传输放大的模拟设计软件CPAP，并讨论了在一定条件下此宽带模型可回归到窄带模型.     

非均匀展宽对超短激光脉冲传播特性的影响

用建立的"预报校正-四阶龙格库塔"数值算法研究了非均匀展宽二能级体系中超短激光脉冲的传播特性。计算结果表明,非均匀展宽线型的线宽对光脉冲传播会产生调制作用。当线宽大于脉冲的频谱宽度时,脉冲面积演化与面积定理相符且脉冲传播平稳;但随着线宽的减小,脉冲面积演化会越来越偏离面积定理,脉冲传播不再平稳并出现"拖尾"振荡。脉冲主峰的峰值和脉冲的传播速度也受到线宽的影响。     

Weak versus strong harmonic-expansion analyses of self-pulsing lasers: II—the inhomogeneously broadened system

A simple harmonic expansion method is applied to investigate some aspects of the dynamic properties of the integro-differential ‘Maxwell-Bloch’ equations that describe the self-pulsing regime of a single-mode inhomogeneously broadened laser. First, we show that the usual small perturbative methods only describe the transient relaxation oscillations, characteristic of the signal relaxing towards its permanent state, either stable or unstable. Second, we show that an adapted strong harmonic expansion analysis applied to the permanent pulsing solutions yields an accurate evaluation of the pulsing frequencies.     

Optical bistable behavior of single-mode fabry-perot lasers with saturable absorber

The present paper is devoted to the optical bistable behavior of Gaussian inhomogeneously broadened single-mode Fabry-Perot lasers with saturable absorber (LSA) in both resonance and nonresonance. The system is described by rate equations based on the dual two-level model with allowance for spontaneous emission and spatial hole-burning. The conditions under which optical bistability (OB) occurs are clearly displayed in phase diagrams. The OB characteristics and stability behavior are investigated in connection with their dependence on the detuning and LSA parameters. Paper submitted by authors in English April 20, 1999.     

The effects of inhomogeneous broadening in an organic microcavity laser

In this work we study the input–output characteristics of an organic vertical cavity surface emitting laser (OVCSEL) with an active layer of Alq3:DCM over 3 orders of magnitude in pump intensity. We find that lasing from this standard inhomogeneously broadened gain medium cannot be described using a single lasing threshold value. Instead, an inhomogeneously broadened distribution of spontaneous emission factors, beta, must be employed in order to correctly model the measured input–output characteristics.     

Superradiance and subradiance in an inhomogeneously broadened ensemble of two-level systems coupled to a low-Q cavity

The collective spontaneous emission of a fully inverted inhomogeneously broadened ensemble of N two-level systems coupled to a single-mode low-Q cavity is investigated numerically using Monte Carlo wave function technique. An intrinsically bi-exponential emission dynamics is found when the time scales of superradiance tau(sr) and inhomogeneous dephasing T2* approximately 1/Deltaomega(inh) become comparable: a fast superradiant is followed by a slow subradiant decay. Experimental configurations using ensembles of quantum dots coupled to optical microcavities are proposed as possible candidates to observe the combined superradiant and subradiant energy relaxation.     

Multiwavelength pulse generation in semiconductor-fiber ring laser using a sampled fiber grating

A novel multiwavelength scheme has been demonstrated using a sampled fiber grating in semiconductor-fiber ring laser. By using semiconductor optical amplifier as an inhomogeneously broadened gain medium, three wavelength channels of 10 GHz are simultaneously generated. The number of the lasing channels can be changed through the polarization state adjustment in the cavity.     

非均匀加宽工作物质"烧孔"效应的烧孔宽度分析

针对激光原理教材中非均匀加宽工作物质的烧孔效应,分析了烧孔宽度的由来,给出了详细推导过程．     

Steering of the Stark Echo Temporal Response

We investigate the effect of external spatially inhomogeneous electric fields on correlations between isochromates of an inhomogeneously broadened spectral line. We use laser excitation at various time intervals between an object laser pulse and its Stark echo response. Also we study the reproducibility of information contained in the Stark echo response and the possibility of steering its temporal form.     

First-Order-Like Transition in Inhomogeneously Broadened Two-Mode Ring Laser Gain-Noise Model

An inhomogeneously broadened two-mode ring laser gain-noise model taking account of both full saturation effects and multiplicative noise induced by gain fluctuations is investigated. By using a corresponding Fokker-Planck equation and perturbation theory proposed by Graham et al. the joint stationary distribution for light intensities is obtained. It is found that a first-order-like transition occurs when laser is operated off resonance.     

Kerr-lens mode-locking of Nd:glass laser

We report what is to our best knowledge the first Kerr-lens mode-locking of a Nd:silicate glass laser. Pulses as short as 64 fs were generated. For a broadband inhomogeneously broadened laser, the formation of the soliton-like pulses requires a minimum amount of negative group velocity dispersion (GVD), and more negative GVD is needed to have stable, self-sustained mode locking.