正色散激光器中的增益导引孤子

采用非线性薛定谔方程模拟了全正色散介质激光器中实现脉冲锁模输出的动态过程,理论表明,不同于工作于净色散为负的孤子锁模激光器以及腔内具有色散延迟线净色散为正的色散管理孤子和自相似脉冲锁模激光器,在纯正色散介质构成的锁模激光器中,增益饱和和增益窄化对形成稳定的锁模脉冲起重要的作用,在两者的作用下脉冲形成增益导引孤子.采用不同的锁模方式在纯正色散光纤锁模激光器中得到了稳定的增益导引孤子锁模,实验结果与理论模拟一致. 关键词： 锁模 正色散 增益导引孤子     

基于非线性偏振旋转锁模的高功率光子晶体光纤飞秒激光振荡器

为了探索大模场面积光子晶体光纤锁模激光器在全正色散锁模域内的耗散孤子锁模机理, 以获得更大的单脉冲能量和更高的峰值功率, 本文搭建了以掺镱大模场面积光子晶体光纤作为增益介质的耗散孤子锁模激光器. 激光器使用环形腔结构, 利用非线性偏振旋转以及滤光片提供的耗散作用实现了稳定的锁模运转. 实验中, 从激光器振荡级直接获得了平均功率10 W, 重复频率49.09 MHz(对应202 nJ的单脉冲能量), 脉冲宽度为1.03 ps的稳定锁模脉冲输出, 经过腔外色散补偿得到的脉冲宽度为95.5 fs.     

输出近百纳焦耳脉冲能量的光子晶体光纤锁模激光器

设计并搭建了一种支持百纳焦耳量级的单脉冲能量输出的锁模光纤激光器.激光器基于σ型腔结构,采用掺Yb偏振型大模场面积光子晶体光纤作为增益介质,利用半导体可饱和吸收镜实现自启动锁模.激光器内没有色散补偿机理,使其工作在全正色散锁模状态.通过在谐振腔内引入多通长腔使激光器的重复频率降低至11.1 MHz,直接获得了平均功率为1.08 W,单脉冲能量为 97 nJ,脉冲宽度为4.17 ps的稳定锁模脉冲输出,经腔外色散补偿,脉冲宽度压缩至740 fs.     

主动锁模光纤激光器的孤子理论分析

系统考虑了光纤激光器腔构参数与锁模脉冲参数的制约关系,建立了完整形式的振幅调制主动锁模光纤激光器的稳态方程;据此方程分析了主动锁模光纤激光器腔参数对锁模孤子脉冲参数的影响;分析了无啁啾孤子脉冲形成条件。     

7.13 W全固态1 319 nm宏微脉冲激光器

 研制了一台高效率全固态平均功率7.13 W的1 319 nm宏微脉冲激光器。激光器采用热稳Z形折叠腔,增益模块采用自行研制的准连续15个二极管芯片环形泵浦的Nd:YAG模块,采用主动声光锁模器作为锁模元件,并在腔内插入倍频KTP晶体对激光器的输出尖峰进行抑制。为了获得稳定的锁模状态,对激光器腔长进行了精确设计和调节。当激光器腔长与锁模器驱动频率匹配时,获取了宏脉冲重复频率400 Hz、脉宽约190 μs,微脉冲重复频率95.6 MHz、脉宽小于1.0 ns的1 319 nm激光脉冲。     

非腔长匹配相干叠加脉冲锁模激光器的理论研究

提出了一个新的非腔长匹配相干叠加脉冲锁模激光器的物理模型,建立了它的数学方程,并进行了模拟计算.计算结果给出了各个参数对相干叠加脉冲锁模激光器运转的影响,以及脉冲宽度压缩速度和各参数之间的关系,获得了实现非腔长匹配相干叠加脉冲锁模激光器运转的最佳条件.     

环形腔自锁模掺钛蓝宝石激光器

实现了环形腔掺钛蓝宝石激光器的自锁模运转。在双向同时锁模时获得脉宽为３６ｆｓ的锁模脉冲；在单向锁模时得到脉宽为３２ｆｓ的锁模脉冲。并对激光器的运转特性进行了分析。     

环形腔自锁模渗钛蓝宝石激光器

实现了环形腔掺钛蓝宝石激光器的自锁模运转，在双向同时锁模时获得宽为３６ｆｓ的我没模脉冲，在单向锁模时得到脉宽为３２ｆｓ的锁模脉冲，并对激光器的运转特性进行了分析。     

自锁模激光器

概述了自锁模激光器的新成就（包括我们自已的工作）。在实验上，自锁模钛宝石激光器可以输出１３ｆｓ的短激光脉冲，这是直接从激光器中获得的最短脉冲；自锁模溴化亚铜激光器可以输出高稳定性的激光脉冲，从而彻底否定了自锁模没有实用价值的传统认识。在理论上，自克尔镜模型解释了自聚焦激光介质引起的锁模现象；增益凹陷模型解释了宽带激光介质自吸收起的锁模现象和窄带激光介质增益谱线分裂引起的锁模现象。最后，对它们的输出     

有源耦合腔激光器锁模特性研究

本文在理论上首次发现有源耦合腔激光器的自启动锁模和时域调制特性,并对其进行了全面的分析和计算.对有源耦合腔激光器的自启动锁模机制和时域调制特性给予详尽的数值计算结果和清晰的物理图象解释,提出在有源耦合腔锁模激光器中可用连续泵浦源代替锁模泵浦源,而且有产生更短的光脉冲可能性.     

Control of the pulse duration in one- and two-axis passively Q-switched solid-state lasers

We study theoretically and experimentally different methods to control the pulses emitted by solid-state lasers passively Q-switched by a saturable absorber. We explore one- and two-axis laser schemes allowing to control the pulse duration, which is ruled by the saturation powers of the transitions in the absorber and in the gain medium. In one-axis lasers, it is shown that the adjustment of the pump and laser beam sizes in the active medium and in the absorber provides an efficient means to control the pulse temporal shape and duration. Furthermore, a two-axis laser cavity supporting so-called forked-eigenstate operation permits to freely adjust the parts of the mode power which circulate in the gain medium and in the absorber. In this case, a lengthening of the pulse duration up to 500 ns is obtained with an increase of the average output power. The theoretical results obtained by using rate equations adapted to each cavity geometry are in close agreement with experiments performed on a diode-pumped Nd³⁺:YAG laser Q-switched by a Cr⁴⁺:YAG saturable absorber. The relevance of the different techniques to control the pulse durations in the framework of potential applications is discussed. Received 3 December 2001     

Generation of 49 fs pulses in a CPM laser pumped by a small-frame Ar+ laser

A colliding pulse mode-locked ring dye laser, pumped by an all-line small frame Ar⁺ laser has been used to generate stable pulses as short as 49 fs with pulse duration and stability similar to those obtained with the usual configuration where a single line of the pump is used. The effects of cavity alignment on the absorber saturation are presented and explained in terms of an analysis of stability of the ring cavity.     

Coupled-cavity passively Q-switched two-Stokes microchip laser

Experimental and theoretical studies of the coupled-cavity diode-pumped Nd:YAG/Cr:YAG microchip lasers with intracavity Raman conversion of laser pulses in a Ba(NO₃)₂ crystal into two Stokes pulses have been made. Two lasers with a different cavity length have been investigated. The minimal pulse durations at the 2nd Stokes wavelength were ??100 ps in the short-cavity laser at pulse energy of 5???J, and the pulse repetition rate reached 20?C24?kHz. The laser and Stokes pulse dynamics, as well as the spatial intensity distribution of the laser and the 1st Stokes beams at the output mirror have been recorded. A model describing such coupled-cavity microchip Raman lasers has been developed. The numerically simulated laser and Stokes pulse dynamics, and the calculated pulse energy, duration, and repetition rate are in good agreement with the experimental data.     

Theoretical analysis of pulse development in a colliding pulse mode-locked dye laser

The pulse development in colliding pulse mode-locked dye lasers is analysed theoretically. The chosen parameters belong to a c.w. argon laser pumped linear resonator arrangement with rhodamine 6G in ethylene glycol as gain medium and DODCI (3,3-diethyloxadicarbocyanine iodide) in ethylene glycol as saturable absorber. The pulse shortening and pulse broadening effects in the laser oscillator are investigated. The steady-state pulse duration is determined by equal pulse broadening and pulse shortening within a single resonator round-trip. The detuning of the absorber jet out of the middle position of the resonator is considered. Multiple transits through the resonator are simulated to study the influence of various resonator and dye parameters on the pulse development and the background signal suppression. Fast relaxations within theS ₁ andS ₀-state of DODCI are necessary for sufficient background suppression to obtain femtosecond pulse trains.     

Theory of passively mode-locked cw dye lasers

The circulation of an ultrashort light pulse in a continuously pumped modelocked dye laser with a linear cavity configuration containing the active dye, the saturable absorber and a bandwidth-limiting elements is treated. The steady-state condition that the pulse shape reproduces after each cavity round-trip leads to a nonlinear integro-differential equation for this pulse shape. An approximate method for the solution of this equation not limited to the case of low laser gain and small pulse energies is given. The stable single pulse region and characteristic pulse parameters, as energy, duration, intensity and asymmetry, are considered in dependence on the laser parameters.     

Subpicosecond pulse generation in synchronously pumped and hybrid ring dye lasers

Subpicosecond pulse generation has been examined in synchronously pumped mode-locked ring dye laser systems. These include hybrid and composite absorber/gain media arrangements as well as a simple synchronous cavity. The shortest pulses recorded were 0.3 ps for the hybrid system, and this has been shown to be critically dependent on the positioning of the absorber jet in the centre of the cavity to better than 50 m. Stable operation for subpicosecond pulse generation has been achieved in the ring configuration with greater wavelength tunability and higher average power conversion efficiency than with conventional cavity arrangements.     

Generation and measurement of frequency-tunable picosecond pulses from dye lasers

Experimental techniques for the generation of frequency-tunable picosecond pulses from passively mode-locked dye lasers are reviewed. Direct photoelectric measurements of pulse durations with a streak-camera of time resolution <3 ps are described. Recent studies of the build-up of pulse shortening and of saturable absorber photochemistry are discussed and related to the mode-locking processes in dye lasers.     

Theoretical and experimental study of the colliding-pulse method for solid-state lasers

The interaction of ultrashort pulses with a two-level saturable absorber is considered in the colliding-pulse regime. The shortening of the Gaussian pulse duration is investigated for a wide range of absorber and pulse parameters and compared with typical contacting-absorber and non-contacting-absorber methods. The analysis of the maximum pulse dynamics taking into account the noise radiation in the context of the fluctuation model shows that in addition to the well-known advantages realized in dye lasers, the colliding-pulse method results in the achievement of shorter durations of the peak pulses in the train near the second threshold. This advantage is shown, both theoretically and experimentally, to be greater for faster the relaxation of the absorber.     

热键合技术的Cr4+:YAG被动调Q激光器理论和实验研究

 采用数值求解被动调Q速率方程，并讨论了基于热键合技术被动调Q激光器的优化方法。通过数值仿真讨论分析了谐振腔的损耗、饱和吸收体的初始透过率、输出镜的反射率和泵浦功率等参数对激光输出的影响。结果表明：输出镜存在最佳透过率，使得输出功率最高和脉冲能量最大；减小饱和吸收体的初始透过率能有效提高脉冲能量，并压缩脉宽，但是会增加阈值泵浦功率；泵浦功率与脉冲重复率和输出功率近似成线性增加，增大泵浦功率可以压缩脉宽。并通过实验验证了理论分析的正确性。