Self-starting mode-locked picosecond Ti：sapphire laser by using of a fast SESAM

A stable continuous wave mode-locked picosecond Ti:sapphire laser by using a fast semiconductor saturable absorber mirror (SESAM) is demonstrated. The laser delivers pulse width of 20 ps at a central wavelength of 813 nm and a repetition rate of 100 MHz. The maximum output power is 1.34 W with pump power of 7 W which corresponds to an optical--optical conversion efficiency of 19.1%.     

Synchronization of an Ultrafast Ti：Sapphire Laser to the S-Band Microwave

We have synchronized a 102-MHz ultrafast self-mode-locked Ti:sapphire laser to a 2856-MHz rf source with thesample-locking technology. The relative root-mean-square time-jitter is 0.57 ps and the maximum time jitter is2.60ps. This is the first time that synchronization between the ultrafast laser pulse and the s-band microwavehas been accomplished in China. Potential applications include synchronization of lasers and rf power sources inparticle accelerator experiments and high-resolution pump-probe experiments.     

Generation of 7-fs laser pulse directly from a compact Ti:sapphire laser with chirped mirrors

A compact femtosecond Ti:sapphire laser resonator consisting of three chirped mirrors and one output coupler was designed. By accurately balancing the intra- cavity dispersions between Ti:sapphire crystal, air and chirped mirrors, we directly generated the laser pulse shorter than 7 fs at the average power of 340 mW with 3.1 W pump. The repetition rate of the laser oscillator is 173 MHz at the centre wavelength of 791 nm, and the ultrabroaden spectrum covers from 600 nm to 1000 nm. To the best of our knowledge, this is the simplest laser resonator capable of generating sub-10 fs laser pulse.     

Improvement of the large aperture Ti：sapphire amplifiers in the petawatt femtosecond laser system at SIOM

We report the recent improvement on the petawatt (PW) femtosecond Ti:sapphire chirped pulse amplification (CPA) laser system at Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences. By enlarging the sizes of the pump and signal beams in the large aperture Ti:sapphire amplifiers and optimizing the whole laser system, the output laser energy before the pulse compressor is upgraded to 42.6 J. Accordingly, the peak power of the laser system exceeds 1 PW. The shot-to-shot instability of the output laser energy at about 40 J is less than ±5%.     

Proposal of switchable multiwavelength laser with continuously tunable spacing in MgO： APPLN waveguide

A switchable multiwavelength laser with a continuously tunable spacing is proposed and illustrated based on cascaded interactions of the second harmonic and difference-frequency generations in an aperiodically poled MgO-doped lithium niobate (MgO:APPLN) waveguide. The wavelengths and wavelength spacings of the four outputs are continuously varied and controlled by changing the two input pump wavelengths and spacings within a 3-nm flattop bandwidth of MgO:APPLN. In addition, the switchable states of the four outputs can be selected by inputting proper powers of the two pumps. The number of output wavelengths can also be increased by choosing the proper APPLN structure, the total length of MgO:APPLN, and higher powers of input pump lights.     

Design of efficient single-stage chirped pulse difference frequency generation at 7 μm,driven by a dual wavelength Ti:sapphire laser

We present simulations for a design of a high-energy single-stage mid-IR difference frequency generation adapted to a two-color Ti:sapphire amplifier system. The optimized mixing process is based on chirped pulse difference frequency generation (CP-DFG), allowing for a higher conversion efficiency and reduced two-photon absorption losses. The numerical start-to-end simulations include stretching, chirped pulse difference frequency generation and pulse compression. Realistic design parameters for commercially available nonlinear crystals (GaSe, AgGaS₂, LiInSe₂, LiGaSe₂) are considered. Compared with conventional unchirped DFG directly pumped by Ti:sapphire technology, we predict a threefold increase in the quantum efficiency. Our CP-DFG scheme provides up to 340 μJ pulse energy directly at 7.2 μm when pumped with 8 mJ and supports a bandwidth of up to 350 nm. The resulting 240 fs mid-IR pulses are inherently phase stable.     

闪光灯泵浦钛宝石可调谐激光器

为了提高灯泵钛宝石激光器的输出能量和效率，对灯泵钛宝石激光器进行了大量的试验研究工作。对国产氙灯进行了快速放电和寿命试验；测得了在不同放电电流密度情况下的氙灯发光光谱分布；试验采用双灯串接泵浦，双棱镜色散光学谐振腔，平平腔型，调谐范围为７５０～９５０ｎｍ，在中心波长８００ｎｍ处得到激光输出能量为８９３ｍＪ，电光转换效率为０．８９％。该激光器的阈值约为１５Ｊ。     

Thermal characteristics of Nd~(3 )-doped fiber ring laser pumped by Ti:sapphire tunable laser

A Nd(3 )-doped fiber ring laser pumped by a CW Ti:sapphire tunable laser is reported. The characteristics of the system are studied for the first time at 77K and 300K. The results show a lower threshold and a higher slope efficiency at 77K than that at 300K. Applications of the Nd~(3 )-doped fiber ring laser in a multiplexing fiber sensor system and a fiber-ring-laser type temperature sensor are discussed.     

Thermal characteristics of Nd3+-doped fiber ring laser pumped by Ti:sapphire tunable laser

A Nd(3+)-doped fiber ring laser pumped by a CW Ti:sapphire tunable laser is reported. The characteristics of the system are studied for the first time at 77K and 300K. The results show a lower threshold and a higher slope efficiency at 77K than that at 300K. Applications of the Nd~(3+)-doped fiber ring laser in a multiplexing fiber sensor system and a fiber-ring-laser type temperature sensor are discussed.     

Temporal characteristics of Ti: sapphire laser pumped synchronously by bounded pulse train

A Ti: sapphire laser pumped synchronously by a bounded frequency-doubled pulse train of a pulsed mode-locked Nd : YAG laser was presented. The temporal characteristics of the laser and optimal conditions of generating stable ultrashort pulses are also given.     

Noncascading THz-wave parametric oscillator synchronously pumped by mode-locked picosecond Ti:sapphire laser in doubly-resonant external cavity

A noncascading terahertz (THz) wave parametric oscillator synchronously pumped by a mode-locked picosecond Ti:sapphire laser whose average power was less than 1 W was demonstrated with a noncollinear phase-matching MgO:LiNbO₃ crystal in an external enhancement cavity doubly resonant for both pump (780 nm) and signal (781-784 nm) waves. In the external cavity, in which the pump wave enhanced so as to reduce the pumping threshold of parametric processes, the signal wave could also resonate and thus be enhanced simultaneously, resulting in a THz wave output at approximately 0.9 THz as the idler wave. The novel dual enhancement of pump and signal waves reduced the threshold pumping intensity to approximately 50 MW/cm², which was much lower than that of a conventional externally pumped THz wave parametric oscillator with a crystal.     

An all-solid-state high power quasi-continuous-wave tunable dual-wavelength Ti：sapphire laser system using birefringence filter

This paper describes a tunable dual-wavelength Ti:sapphire laser system with quasi-continuous-wave and high-power outputs. In the design of the laser, it adopts a frequency-doubled Nd:YAG laser as the pumping source, and the birefringence filter as the tuning element. Tunable dual-wavelength outputs with one wavelength range from 700~nm to 756.5~nm, another from 830~nm to 900mn have been demonstrated. With a pump power of 23~W at 532~nm, a repetition rate of 7~kHz and a pulse width of 47.6~ns, an output power of 5.1~W at 744.8~nm and 860.9~nm with a pulse width of 13.2~ns and a line width of 3~nm has been obtained, it indicates an optical-to-optical conversion efficiency of 22.2{\%}.     

采用多通腔望远镜谐振腔结构的10MHz重复频率飞秒钛宝石激光器特性研究

通过在钛宝石激光腔内引入望远镜长腔系统增加腔长,实现了重复频率低到10?MHz的飞秒激光振荡,在5?W的抽运功率下获得了平均输出功率200?mW、单脉冲能量20?nJ的稳定输出. 在此基础上分析了腔内不同色散情况下的输出脉冲光谱和脉宽特性,结果表明在腔内存在一定负色散的情况下,锁模脉宽可接近转换极限,最短脉宽可达56?fs. 而在正色散的情况下,锁模输出的脉宽较宽,并且随着腔内正色散的增多,脉宽可到大于600?fs,锁模光谱也呈马鞍形. 关键词： 钛宝石激光器 飞秒脉冲 低重复频率 望远镜腔     

PW级掺钛蓝宝石激光放大器中横向寄生振荡控制

 介绍了目前世界上在建的第一台掺钛蓝宝石激光系统中大口径晶体内横向寄生振荡的抑制方法。采用一种掺炭的热塑料MeltMount 1.704作为折射率匹配材料，掺入炭粉作为吸收体。理论上它可以将晶体中的寄生振荡阈值从13增加到2100。     

灯泵钛宝石激光器调Q运转

论述了色散棱镜谐振腔调Q运转方法。其中棱镜既起到波长调谐色散元件的作用 ,又起到Q开关起偏器的作用 ,省掉了制作难度大的宽带起偏器。为了使晶体高压随波长调谐同步运转 ,采用了单片机控制全反射镜驱动电源 ,同时也控制调Q电压 ,使全反射镜的转动与施加在晶体上的高压同步运行 ,达到了宽带调谐与调Q电压同步运转的目的 ,获得了波长调谐巨脉冲激光。实验中应用精确数字退压延迟技术和晶压与波长调谐同步运转方法 ,获得了激光脉宽 31ns、能量 2 70mJ的结果