单脉冲飞秒激光时域参数测量技术研究

钛宝石飞秒激光放大系统具有重复频率低、脉冲波形复杂等特点，为准确测量其峰值功率，提出对单次脉冲波形和脉冲宽度测量的需求。介绍了单脉冲飞秒激光时域波形和脉冲宽度的测量原理和测量方法，设计了基于频率分辨光学开关法的单脉冲飞秒激光时域参数测量装置。讨论了单脉冲飞秒激光时域参数测量校准面临的问题及解决方法。     

腔模可调的高平均功率飞秒激光再生放大器

介绍了一种腔模可调的高平均功率飞秒激光再生放大器.通过调节再生腔内模式大小补偿热透镜效应,从而获得高效率、高平均功率的激光放大.利用该再生放大结构,在1 kHz重复频率、20 W功率抽运下,获得了平均功率为6.5 W的放大光输出,压缩后的功率为4.8 W、脉冲宽度为35 fs.腔型计算和实验结果均表明该腔型结构能很好地用于高平均功率飞秒激光放大,是进一步进行后续放大的理想前端.     

采用光谱展宽技术的钛宝石飞秒激光放大器

报道了飞秒激光啁啾脉冲放大器中的激光脉冲光谱展宽技术，实验中使用了几种光谱展宽元件，结果表明使用激光光谱展宽元件能有效地将飞秒激光脉冲 光谱展宽，抑制了飞秒激光放大器中常见的激光脉冲光谱增益窄化现象，从飞秒放大系统的振荡级输出28fs种子脉冲，放大后得到了重复频率为10Hz、峰值功率为1．6TW、脉冲宽度37．5fs的超短强飞秒激光脉冲 。     

基于大基模体积的10mJ飞秒钛宝石激光再生放大器

文章报导了基于大基模体积的高能量飞秒钛宝石激光再生放大器的设计与实验研究,在重复频率10 Hz、抽运能量60 mJ的激励下,得到了单脉冲能量17.4 mJ的种子脉冲放大结果,压缩后的脉冲宽度为40.6 fs,能量为13.9 mJ.借助于此大基模体积再生腔,仅增加一级多通放大,实现了峰值功率达1.9 TW飞秒激光脉冲输出.结果表明,大模体积再生放大不仅降低了后续放大对抽运能量的要求,也可以单独压缩实现再生腔直接输出10 mJ量级的飞秒激光脉冲,是大能量高峰值功率飞秒激光系统的优质前端.     

飞秒激光脉冲的高效率放大研究

介绍了采用多通放大的飞秒脉冲掺钛蓝宝石激光放大系统,分析讨论了提高放大效率及缩短脉冲宽度的技术方法。在仅用能量２９０ｍＪ的倍频Ｎｄ：ＹＡＧ激光泵浦下,得到了输出峰值功率大于１．４ＴＷ、脉宽２５ｆｓ、重复频率１０Ｈｚ的超短超强激光脉冲。     

输出能量4mJ的1kHz飞秒掺钛蓝宝石激光再生放大研究

针对高能量千赫兹重复频率飞秒激光的应用需求,设计了一套采用线性再生腔结构的高效率飞秒钛宝石激光啁啾脉冲放大系统.通过优化腔型设计,在重复频率为1 kHz、单脉冲能量为20 mJ的527 nm激光抽运下,将展宽后的800 nm啁啾脉冲激光的能量放大到5.8 mJ,对应斜效率达到30.7%.进一步通过色散补偿压缩脉冲宽度,获得了单脉冲能量为4 mJ、脉冲宽度为45.7 fs的输出,稳定性测量表明激光的能量抖动仅为0.18%(均方根值).     

飞秒激光脉冲的高效率放大研究

 介绍了采用多通放大的飞秒脉冲掺钛蓝宝石激光放大系统,分析讨论了提高放大效率及缩短脉冲宽度的技术方法。在仅用能量290mJ的倍频Nd:YAG激光泵浦下,得到了输出峰值功率大于1.4TW、脉宽25fs、重复频率10Hz的超短超强激光脉冲。     

可用于超精细加工的高重复率、高光束质量飞秒再生放大脉冲的产生研究

通过飞秒放大增益饱和理论及飞秒脉冲展宽的理论计算与分析，指出在优化放大腔结构参数及改变抽运光能量情况下，可以在省略展宽器基础上实现中等能量的飞秒脉冲再生放大.以此为依据，采用低抽运能量和放大腔中钛宝石晶体离焦技术，成功地进行了无展宽器的高重复率飞秒钛宝石再生放大及压缩技术的实验研究，并获得了高光束质量的飞秒放大光脉冲，放大光脉冲能量大于100μJ，重复频率为1kHz，光谱带宽7.7nm，压缩后脉宽500fs. 关键词： 飞秒光脉冲 再生放大 光束质量 增益饱和     

采用环形再生腔结构的飞秒激光啁啾脉冲放大研究

采用环形再生腔结构的啁啾脉冲放大技术方案, 在重复频率100 Hz,单脉冲能量33.1 mJ的532 nm激光抽运下, 从钛宝石激光中获得了单脉冲能量9.84 mJ的放大输出, 对应的斜效率达33.1%.在重复频率10 Hz的情况下, 同样获得了单脉冲能量为9.64 mJ, 对应斜效率达36.8%的高效率放大结果. 通过色散补偿压缩该啁啾激光脉冲后的单脉冲能量为6.36 mJ, 脉冲宽度为59.7 fs. 测量结果表明典型的能量不稳定度为1.85%. 关键词： 啁啾脉冲放大 再生放大 飞秒激光 环形腔     

高功率线偏振皮秒脉冲簇Yb光纤激光器

以一个增益调制的分布式布喇格反射结构的半导体激光器为种子源,设计了一个高功率皮秒脉冲簇输出的线偏振掺镱光纤激光器.种子源输出脉冲宽度200ps,重复频率350MHz.在预放大中插入一个基于一级衍射透过的声光调制器实现了皮秒脉冲簇形式的激光输出,脉冲簇的重复频率在10~500kHz范围可调.皮秒脉冲簇激光通过一个基于大模场面积保偏Yb光纤的功率放大级,获得了高功率线偏振激光输出,平均功率83 W,偏振消光比优于15dB.当脉冲簇重复频率固定在100kHz,脉冲簇中同时存在350个子脉冲时,获得峰值功率12kW的皮秒激光输出.与传统连续脉冲输出的激光器相比,该系统能够实现脉冲簇的输出,有利于峰值功率的进一步提高,可应用于激光微加工领域.     

二极管端面泵浦的附加脉冲锁模的Nd：YLF激光器

研究了二极管端面泵浦的附加脉冲锁模的Ｎｄ：ＹＡＧ激光器并分析了脉冲压缩原理及自启动机制,在最大泵浦功率为２．４Ｗ时,得到重复频率为１３４ＭＨｚ、脉宽为２ｐｓ、有效输出功率７６ｍＷ、相应峰值继２８３Ｗ、波长为１．０５３μｍ、波长为１．０５３μｍ的稳定的连续模脉冲序列。     

光纤激光器直接输出的高功率贝塞尔超短脉冲

构建了一种能够直接输出高功率贝塞尔超短脉冲的光纤激光放大器. 该方案基于在光纤端面特殊设计和制备的微型负轴锥镜, 针对常规超短脉冲光纤激光放大系统所设计, 不需要引入其他分立整形器件, 避免了目前基于轴锥透镜产生贝塞尔光束的通用方法所带来的额外烦琐准直工作, 极大简化了产生贝塞尔光束的方法. 其中的微型负轴锥镜由聚焦粒子束刻蚀法在一段掺镱大模场光子晶体光纤的端面制备, 它和光纤激光系统中的固有准直透镜构成了集成化的光束整形器件. 基于数值模拟结果成功搭建的系统与理论设计一致, 直接输出了在米量级具有高度准直无衍射特性的啁啾皮秒贝塞尔超短脉冲波包, 平均功率高达10.1 W, 对应脉冲能量178 nJ, 经过光栅对压缩后脉冲宽度可达140 fs. 关键词： 衍射 超短脉冲产生 光纤器件 光纤激光器     

Wavelength tunable ultra-short pulses based on a flat broadband spectrum generated in a nonlinear ytterbium-doped fiber amplifier

We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum(center wavelength and linewidth) are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.     

High-power 200 fs Kerr-lens mode-locked Yb:YAG thin-disk oscillator

We demonstrate a power-scalable Kerr-lens mode-locked Yb:YAG thin-disk oscillator. It delivers 200 fs pulses at an average power of 17 W and a repetition rate of 40 MHz. At an increased (180 W) pump power level, the laser produces 270 fs 1.1 μJ pulses at an average power of 45 W (optical-to-optical efficiency of 25%). Semiconductor-saturable-absorber-mirror-assisted Kerr-lens mode locking (KLM) and pure KLM with a hard aperture show similar performance. To our knowledge, these are the shortest pulses achieved from a mode-locked Yb:YAG disk oscillator and this is the first demonstration of a Kerr-lens mode-locked thin-disk laser.     

Theory of combined AM and high-harmonic FM mode locked laser

Closed form solutions for a simultaneously AM and high-harmonic FM mode locked laser system is presented. Analytical expressions for the pulsewidth and pulsewidth-bandwidth products are derived in terms of the system parameters. The analysis predicts production of 17 ps duration pulses in a Nd:YAG laser mode locked with AM and FM modulators driven at 80 MHz and 1.76 GHz for 1 W modulator input power. The predicted values of the pulsewidth-bandwidth product lie between the values corresponding to the pure AM and FM mode locking values.     

High-conversion-efficiency and tunable phase-stabilized infrared parametric laser source

High-conversion-efficiency and tunable self-phase-stabilized infrared laser pulses have been generated from a two-stage optical parametric amplifier. With a 1 kHz repetition rate 800 nm pump source, the output idler pulses are tunable from 1.2 to 2.4 μm, and the maximum output average power of the idler pulses is >2 W with the total 7.4 W pump power, and the maximum parametric conversion efficiency in the final optical parametric amplifier is near 60%. Due to the differential frequency process, the output idler pulses is self-phase-stabilized, the phase fluctuation can reach 0.374 rad (rms).     

Ultrawide tunable Er soliton fiber laser amplified in Yb-doped fiber

A Raman-shifted and frequency-doubled high-power Er-fiber soliton laser for seeding an efficient high-power Yb fiber femtosecond amplifier is demonstrated. The Raman-shifted and frequency-doubled Er-soliton laser is tunable from 1.00 to 1.070microm and produces bandwidth-limited 24-pJ pulses at a repetition rate of 50 MHz with a FWHM pulse width of 170 fs at 1.040microm . The Yb(3+) amplifier has a slope efficiency of 52% and generates 3-ps linearly chirped pulses with an average power of 0.8 W at 1.05microm . After pulse compression, 74-fs bandwidth-limited pulses with an average power of 0.4 W and a pulse energy of 8 nJ are generated.     

Efficient continuous-wave and Q-switched operation of a diode-pumped Yb:KLu(WO4)2 laser with self-Raman conversion

Efficient cw and passively Q-switched operation with self-stimulated Raman scattering conversion was demonstrated in a compact diode-pumped Yb:KLu(WO4)2 laser. A cw output power of 3.28 W was obtained with an optical efficiency of 48.2% and a slope efficiency of 78.2% with respect to the incident pump power. Stable Q-switched operation was achieved with a Cr4+:YAG saturable absorber, generating 32.4 microJ fundamental pulses with a duration of 1.41 ns at 1030.6 nm and 14.4 microJ Raman pulses with a duration of 0.71 ns at 1137.6 nm. At an incident pump power of 7.0 W, the average output power reached 0.9 and 0.4 W for fundamental and Raman radiation, with slope efficiencies of 32.1% and 14.1%, respectively.     

Experimental and Theoretical Study of the Generation and Non-Linear Conversion of Picosecond Bursts from an Amplified Ytterbium-Doped Fiber Laser System

Abstract

This article presents an experimental and theoretical study of the generation of picosecond bursts by a non-polarization-maintaining ytterbium-doped fiber master oscillator fiber amplifier system. The peak power and pulse energy of the burst are higher than 45 kW and 350 nJ at 700 kHz, respectively. The master oscillator fiber amplifier was used to generate 3 W of green and 200 mW of UV light with conversion efficiencies of 16% and 8%, respectively. The enhancement of conversion efficiency by the pulse burst compared with regular pulses was analyzed and attributed to dynamically saturated gain of the pump-power-limited fiber amplifier.     

High-power diode-directly-pumped tenth-order harmonic mode-locked TEM00 Nd:YVO4 laser with 1 GHz repetition rate

A high-efficiency high-power diode-directly-pumped tenth-order harmonic mode-locked TEM₀₀ Nd:YVO₄ laser with 1 GHz repetition rate was first demonstrated. The maximum output power was 10.4 W with optical-optical efficiency of 41.8% and slope efficiency of 78.1%, respectively, the pulse width was about 30 ps at the output power of 9.6 W. Based on the large third-order nonlinearity of Nd:YVO₄, the tenth-order harmonic mode-locked pulses were induced by the intensity-dependent Kerr effect and the cooperative action of counter-propagating pulses colliding in the laser crystal for a colliding-pulse-modelocking-like cavity. The pulses were further modulated by a semiconductor saturable absorber mirror.