双包层Er3+/Yb3+共掺光纤激光器动态特性的分析

分析了弛豫振荡前上能级Er³⁺、Yb³⁺粒子数的变化和弛豫振荡时Er³⁺上能级粒子数的变化情况以及弛豫振荡时激光功率的变化规律,结果表明:弛豫振荡时的激光峰值功率远大于稳态时的激光功率.     

3μm与2μm级联振荡Ho3+:ZBLAN光纤激光器的动态特性分析

基于传输速率方程,对Ho3+:ZBLAN光纤激光器的动态特性--上能级粒子数以及输出激光功率的弛豫振荡特性进行了数值分析.通过忽略光纤参数对传输方向的依赖性,抽运光和信号光的功率传输方程被分别简化处理.结果表明,在5I6能级的粒子数首先经历一次弛豫振荡后,5I6和5I7能级的粒子数交替弛豫振荡并达到稳态;同样,在3μm波长的激光功率首先经历一次弛豫振荡后,3μm和2μm波长的激光功率交替弛豫振荡并达到稳态,而且,弛豫振荡时的峰值功率远大于稳态时的激光功率.     

3μm与2μm级联振荡Ho3+:ZBLAN光纤激光器的动态特性分析

基于传输速率方程，对Ho³⁺:ZBLAN光纤激光器的动态特性——上能级粒子数以 及输出激光功率的弛豫振荡特性进行了数值分析.通过忽略光纤参数对传输方向的依赖性，抽运光 和信号光的功率传输方程被分别简化处理.结果表明，在⁵I₆能级的 粒子数首先经历 一次弛豫振荡后，⁵I₆和⁵I₇能级的粒 子数交替弛豫振荡并达到稳态；同 样，在3μm波长的激光功率首先经历一次弛豫振荡后，3μm和2μm波长的激光功率交替弛豫 振荡并达到稳态，而且，弛豫振荡时的峰值功率远大于稳态时的激光功率. 关键词： 光纤激光器 动态特性 光纤激光理论 钬光纤     

掺钕光纤放大器的弯曲损耗对增益的影响

利用掺钕光纤放大器的粒子数速率方程、功率传输方程和光纤弯曲损耗公式,对光纤弯曲损耗所引起的增益变化进行了数值模拟,分析了对于不同半径和波长下光纤弯曲损耗对光纤增益的影响,结果表明,对于一定长度的光纤,其增益随弯曲半径的减小而减小,当弯曲达到一定值时,增益发生急剧的降低;随弯曲半径的减小,其增益谱线发生下移,这对实验研究有着重要的指导意义。     

LD泵浦掺铥(Tm3+)光纤激光器的数值分析

首先从掺铥光纤激光器的速率方程和光传输方程出发,建立数学模型,通过Matlab软件进行数值计算,分析了泵浦光和激光沿光纤的分布以及各能级离子数的变化.在不同掺杂浓度下,研究了小信号增益与入纤泵浦功率的关系以及泵浦光和激光功率与增益介质长度的关系.在不同泵浦功率下,研究了输出功率与输出耦合镜反射率的关系.进一步对不同泵浦吸收系数,研究了斜率效率和泵浦阈值与光纤长度的关系.分析结果表明存在最佳光纤长度和最佳耦合输出透过率,使得激光输出功率达到最佳值.     

室温条件下掺铒光纤中光脉冲群速可控特性的研究

利用相干布居振荡技术在介质吸收光谱上产生烧孔，孔宽大约为基态粒子数恢复时间的倒数. 由增益理论分析得到不同抽运光功率对介质吸收状态的影响. 在介质的吸收区域，振荡导致光脉冲经历饱和吸收，脉冲传输延迟；在介质的增益区域，振荡又导致光脉冲经历增益饱和，脉冲传输超前. 应用此技术在掺铒光纤中实现了光速人为可控. 在掺铒光纤晶体中观测到了最慢为2.857×10³m/s的光速减慢传输，相应感生群折射率为10.5×10⁴. 根据布居振荡效应及增益理论，由速率方程出发，得到了 关键词： 光谱烧孔 相干布居振荡 饱和吸收 慢光     

LD泵浦掺铥(Tm3+)光纤激光器的数值分析

首先从掺铥光纤激光器的速率方程和光传输方程出发，建立数学模型，通过Matlab软件进行数值计算，分析了泵浦光和激光沿光纤的分布以及各能级离子数的变化。在不同掺杂浓度下，研究了小信号增益与入纤泵浦功率的关系以及泵浦光和激光功率与增益介质长度的关系。在不同泵浦功率下，研究了输出功率与输出耦合镜反射率的关系。进一步对不同泵浦吸收系数，研究了斜率效率和泵浦阈值与光纤长度的关系。分析结果表明：存在最佳光纤长度和最佳耦合输出透过率，使得激光输出功率达到最佳值。     

三能级光纤激光器速率方程组的阈值解析解

 在考虑了泵浦损耗及激光损耗的情况下，解析求解了阈值泵浦下的三能级光纤激光器速率方程组，获得了泵浦功率阈值的显函数解析表达式，泵浦功率沿光纤变化的隐函数表达式，以及用功率变化表示的各个能级的粒子数密度随位置变化的显函数表达式。并利用这些表达式对光纤激光器的阈值特性进行了研究，研究表明：泵浦功率阈值随泵浦损耗系数增大而增大；激光上能级粒子数密度随归一化位置呈下降趋势，而下能级粒子数密度的变化与此相反；泵浦功率阈值越大(光纤长度越长),净增益系数随归一位置下降就越快。所获得的结果适用于单包层和双包层光纤激光器。     

双包层Er-Yb共掺光纤放大器上能级粒子数分布研究

基于速率方程和功率传播方程, 数值分析了双包层Er-Yb共掺光纤放大器在波长为972nm的泵浦光作用下, 分别采用三种不同泵浦方式, 其Er3+和Yb3+上能级粒子数分布情况. 数值结果表明,Er3+上能级粒子数分布受信号功率影响作用大, 激发率基本保持在50％以上; Yb3+上能级粒子数分布受泵浦功率影响作用大, 激发率基本保持在10％以下, 该结论对双包层Er-Yb共掺光纤放大器的性能研究具有一定指导意义.     

准分子宽带泵浦碱金属激光器泵浦特性分析

建立了以Rb-Ar混合气体为增益介质的四能级准分子宽带泵浦碱金属激光器(XPAL)含时速率方程模型,计算得到了运转过程各能级粒子数和腔内激光强度随时间的变化曲线。结果表明:XPAL的阈值泵浦强度很高,泵浦源谱宽与吸收线宽匹配不能达到提高吸收效率、降低阈值的目的; 在泵浦功率一定的条件下, 增加介质长度和温度可以提高吸收效率,但将降低单位体积泵浦速率; XPAL成功的关键在于实现有效的泵浦吸收。     

Analysis of transient features of selfterminating copper vapour lasers based on rate equations

Transient features of self-terminating copper vapour lasers (CVLs) based on rate equations are analysed with approximate and exact numerical treatments. It is demonstrated from the former analysis that a predictable maximum value of the laser output in a pulsed CVL is at most the order of one hundred times the steady-state value and from the latter analysis that the features of relaxation oscillation of the CVL on the phase-plane are different from those in the usual relaxation oscillation.     

医用3μm与2μm级联振荡钬光纤激光器的工作原理与初步设计

分析了医用3μm与2μm级联振荡Ho³⁺:ZBLAN光纤激光器的工作原理,首次给出了1.1μm带泵浦下级联振荡Ho³⁺:ZBLAN光纤激光器的动态及稳态速率方程,最后给出了级联振荡Ho³⁺:ZBLAN光纤激光器的初步设计.     

超短脉冲掺Yb3+光纤激光器实验研究

报道了掺Yb3+光纤激光器产生超短脉冲的实验研究超短脉冲激光器抽运源采用波长为976 nm的半导体激光器,采用非线性偏振旋转相加脉冲锁模技术,通过调节偏振控制器的方向,实现了掺Yb3+光纤激光器的稳定锁模输出,获得了最大输出功率为7.02 mW,脉冲激光光谱宽度为6 nm,重复频率为13.7 MHz.     

强泵浦下掺Yb3+双包层光纤激光器输出特性数值分析和实验研究

对强泵浦下线形腔掺Yb3+双包层光纤激光器输出特性进行了理论和实验研究。通过数值模拟,分析了泵浦光及激光在光纤中的分布、输出功率与泵浦功率的关系、光纤长度及腔镜反射率对激光输出功率的影响。在实验中,利用D型掺Yb3+双包层光纤获得了输出功率10 6W的光纤激光输出,斜率效率达86%。测量了在不同输出耦合条件下的输出功率、阈值泵浦功率和斜率效率,理论分析与实验结果基本一致,为进一步提高光纤激光器功率提供了理论和实验依据。     

Theoretical study of Pr3+:ZBLAN upconversion ultraviolet fiber laser based on 4f5d state

A theoretical study of the kinetics of two-step-excitation upconversion ultraviolet cw fiber laser based on the 4f5d state in Pr3+:ZBLAN is performed using steady population rate equations and light propagation equations. Under different Pr3+ concentrations, the dependence of the threshold pump powers on the other pump power, the variations of laser output power with reflectivity of output coupler, pump powers and fiber length as well as the dependence of the optimum fiber length on pump powers are investigated.The results predict some optimum laser parameters for maximizing output power.     

Effect of steady-state conditions on self-pulsing characteristics of Yb-doped cw fiber lasers

Fiber laser resonator configurations have been analyzed theoretically on the basis of steady-state rate equations to optimize the laser conversion efficiency. Evolution of the pump- and signal powers and the saturated gain coefficient along the length of the laser medium has been simulated for high- and low-finesse resonators in forward- and backward pumping schemes. The corresponding fiber laser configurations have been setup to verify the results of simulation. Backward pumping configuration in an Yb-doped fiber laser has been found to be the most efficient, and in this configuration a maximum cw output power of 10.75 W in single transverse mode with an optical-to-optical conversion efficiency of 62.5% has been achieved. The laser output spectrum was peaked at 1093 nm with full-width at half-maximum (FWHM) line-width of about 9 nm. In the low-finesse resonator configuration, it has been found that experimental observations differ from theoretical simulation results. In this case, output power from both ends ceases to increase linearly beyond 1.8 W, and starts fluctuating due to the onset of strong random self-pulsing phenomenon. Our investigation shows that a non-uniform steady-state gain along the fiber length facilitates the self-pulsing process.     

Rate equations studies on coherently combined fiber lasers connected by an optical coupler

Attempt has been made to apply the steady-state rate equations to study two coherently combined Er³⁺-doped fiber lasers joined by an optical fiber coupler. In order to establish the boundary conditions, which are necessary for solving the equations, we have taken into consideration the fact that a constructive interference at the coupler assures that the laser radiations from both constituent lasers are directed to the coupler output port to which a reflection mirror defining both lasers is attached. Consequently, effective reflectivity, provided by the coupler-mirror combination, can be specified in terms of the laser powers of both laser signals, and the rate equations describing the compound system can be solved. Using the derived solutions, quantitative investigations can be made on the influences of different laser parameters. For example, the influence of the length difference between doped fibers, the splitting ratio of the coupler and power difference between the two pump radiations have been given in this report.