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Philip J D'Amico C Chériaux G Couairon A Prade B Mysyrowicz A 《Physical review letters》2005,95(16):163901
Femtosecond laser filamentation is studied in a broadband amplifying medium, sapphire doped with electronically excited Ti ions. Evidence for fluence amplification of self-guided pulses, increase of filamentation length, as well as a lowering of the input laser power necessary for filamentation is reported. 相似文献
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W. Shuicai Z. Changjun H. Junfang Y. Hongru X. Dong H. Xun 《Applied physics. B, Lasers and optics》1999,69(3):211-216
We report the theory and experiments of a two-wavelength bi-tuning femtosecond Ti:sapphire laser. The cross-mode-locked gain
competition is described with numerical solution and operation of the laser is accomplished in which two trains of femtosecond
pulses cross in the Ti:sapphire rod. For this reason, a cross-bearings technique is used. The laser resonator is a six-mirror
bi-cavity, and two beams of pump lights cross in Ti:sapphire crystal. Two trains of sub-30 fs cross-mode-locked pulses have
been generated with independent tunable wavelength when the pump power of the argon laser is approximately 5 W. As the design
of the bi-cavity is fine, not only strong gain competition is overcome, but also stable output characteristics are performed.
Received: 21 July 1998 / Revised version: 5 January 1999 / Published online: 30 July 1999 相似文献
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We report an enhancement cavity for femtosecond Ti:sapphire laser at the repetition rate of 170 MHz. An enhancement factor of 24 is obtained when the injecting pulses have an average power of 1 W and a pulse duration of 80 fs. By placing a BBO crystal at the focus of the cavity, we obtain a 392-m W intracavity doubled-frequency laser, corresponding to a conversion efficiency of 43%. The output power has a long-term stability with a root mean square(RMS) of 0.036%. 相似文献
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We report a mode-locked Ti:sapphire femtosecond laser emitting 42 fs pulses at a 10 GHz repetition rate. When operated with a spectrally integrated average power greater than 1 W, the associated femtosecond laser frequency comb contains approximately 500 modes, each with power exceeding 1 mW. Spectral broadening in nonlinear microstructured fiber yields comb elements with individual powers greater than 1 nW over approximately 250 nm of spectral bandwidth. The modes of the emitted comb are resolved and imaged with a simple grating spectrometer and digital camera. Combined with absorption spectroscopy of rubidium vapor, this approach permits identification of the mode index and measurement of the carrier envelope offset frequency of the comb. 相似文献
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飞秒激光脉冲的载波包络相移测量与控制是实现阿秒脉冲与光学原子钟的重要内容,在利用光子晶体光纤扩展飞秒钛宝石激光振荡器光谱的研究基础上,通过自参考技术测量并优化了该激光输出脉冲的载波包络相移所引起的拍频信号.实验上采用半导体抽运的倍频Nd:YVO4532nm激光器作为抽运源,对钛宝石激光器所产生的平均功率500mW、脉宽18fs的光脉冲进行拍频测量后观察到约23MHz的频移,对应于每周期053π的载波包络相移.飞秒激光脉冲载波包络相移测量的实现对于进一步利用电子反馈系统精确控制载波包络相移,从而得到高稳定的飞秒激光频率梳具有重要意义.
关键词:
载波包络相移
光子晶体光纤
飞秒
超连续 相似文献
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W. Zhang L. Li Z. B. Wang A. A. Pena D. J. Whitehead M. L. Zhong Z. Lin H. W. Zhu 《Applied Physics A: Materials Science & Processing》2012,108(2):291-297
Zinc oxide and titanium dioxide composite thin films were prepared on Corning 7059 glass substrates by co-sputtering. The reactive gas-surroundings used was ultrahigh purity oxygen. To analyze the structural, optical and photocatalytic properties of the ZnO?CTiO2 samples, X-ray diffraction (XRD), atomic force microscopy (AFM), optical absorption, Raman spectroscopy and methylene blue bleaching were carried out at room temperature. XRD patterns indicate the presence of TiO2 (anatase and rutile phases), ZnO, ZnTiO3, and Zn2TiO4 crystalline structures. AFM images allow the observation of non-homogeneous surface in the ZnO?CTiO2 system, suggesting the separation of different crystalline phases in the composite. Raman studies exhibit different spectra in the films depending on the area analyzed, which can be interpreted as a result of the existence of well separated crystalline regions as seen in AFM images. The photocatalytic activity (PA) of TiO2?CZnO?CZnTiO3?CZn2TiO4 composite, as expected for adequate coupling semiconductors, is larger than PA of ZnO and TiO2 oxides, used as references. A simple proposal about the probable alignment of the conduction band, the valence band, and the Fermi level is included. 相似文献
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An 800-MHz self-mode-locked femtosecond Ti:sapphire laser has been developed whose mode-lock frequency can be robustly scanned and modulated. The laser is based on the three-element design of Ramaswamy-Paye and Fujimoto [Opt. Lett. 19, 1756 (1994)]. By translation and modulation of the position of the prismatic output coupler, the mode-lock frequency can be reliably scanned more than 1% and modulated at 80 Hz with a deviation of 2.5 kHz without interrupting the mode lock, changing the pulse length, or inducing significant amplitude modulation. An application in tunable high-resolution terahertz spectroscopy is also demonstrated. 相似文献
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结合特殊的谐振腔设计和半导体可饱和吸收镜,建成了一台低阈值的自启动掺钛宝石激光器 . 分别用3%和12%的输出耦合镜,获得了阈值低至390mW和600mW的稳定锁模脉冲输出. 采 用12%输出耦合镜,在12W抽运时,输出平均功率为114mW,对应的典型脉宽为17fs,谱宽 为47nm. 相对于以往的低阈值克尔透镜锁模激光器,锁模工作的范围区域加宽,减小了操作 难度,提高了稳定性.
关键词:
低阈值
半导体可饱和吸收镜
克尔透镜锁模
掺钛蓝宝石激光器 相似文献
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We propose a way to deliver nanojoule-energy, 100-fs pulses at 800 nm through a few meters of standard optical fiber. Pulses from a mode-locked laser are compressed temporally, and then spectrally, to produce the desired pulses at the end of the fiber. Initial experiments agree well with calculations and demonstrate the benefits of this technique: For an energy of ~0.5 nJ , the delivered pulses are ~5 times shorter than those delivered by other techniques. The issues that must be addressed to scale the technique up to delivered pulse energies of 5 nJ are identified, and the apparatus employs only readily available components. Thus we expect it to find use in the many applications that would benefit from fiber delivery of femtosecond pulses. 相似文献
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Generation of synchronized femtosecond and picosecond pulses in a dual-wavelength femtosecond Ti:sapphire laser 总被引:1,自引:0,他引:1
We obtain synchronized 45-fs and 0.848-ps pulses by achieving cross-mode locking in a double-cavity dual-wavelength femtosecond Ti:sapphire laser. Autocorrelation and cross correlation show that the femtosecond and picosecond pulses are well synchronized, with a timing jitter of 41 fs. Cross-phase modulation dominates the processes of cross-mode locking and synchronization. 相似文献
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We observed emission fromp-quaterphenyl (p-QT) at 360 nm when exposed to the focused light from a femtosecond (fs) Ti:sapphire laser at 850 nm. This wavelength is too long to allow two-photon excitation of p-QT. The emission intensity of p-QT was found to depend on the cube of the laser power at 850 nm, suggesting that excitation occurs due to a three-photon process. The same emission spectrum and single exponential decay times were observed for three-photon excitation at 850 nm as for two-photon excitation at 586 nm and for one-photon excitation at 283 nm. The same rotational correlation times were observed for one-, two-, and three-photon excitation, but higher time-zero anisotropies were observed for two- and three-photon excitation. The steady-state anisotropies for one-, two-, and three-photon excitation are precisely consistent with cos2, cos4, and cos6 excitation photoselection, where is the angle between the electric field of the incident light and the absorption dipole. These experiments were performed with 3×10–5
M solutions of p-QT. Use of such low concentrations was possible because p-QT displays one of the highest apparent cross sections we have observed to date for three-photon excitation. The spatial distribution of the excited fluorescence was less for three-photon excitation than for two-photon excitation of Coumarin 102 at the same 850-nm excitation wavelength. The high cross section, photostability, and clear cos6 photoselection of p-QT make it an ideal three-photon standard for spectroscopy and microscopy. 相似文献
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Ito S. Ishikawa H. Miura T. Takasago K. Endo A. Torizuka K. 《Applied physics. B, Lasers and optics》2003,76(5):497-503
We present a 7-TW Ti:sapphire laser system operating at 50 Hz for laser Compton femtosecond X-ray generation. This laser system
delivers 8.4 W of average output power at a repetition rate of 50 Hz with a pulse width of 24 fs. It demonstrates successful
management using a dynamically stable resonator in the regenerative amplifier and compensation for thermal lensing by a convex
mirror in a ring-type four-pass power amplifier. We also present the results of closed-loop corrections for distorted wavefronts
of amplified and compressed laser pulses, using an adaptive optical system consisting of a Shack–Hartmann-type wavefront sensor
and a deformable mirror. This closed-loop correction results in dramatic improvements, reducing wavefront distortions below
0.05 λ rms.
Received: 31 October 2002 / Revised version: 3 March 2003 / Published online: 5 May 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/61-3349, E-mail: ito@festa.or.jp 相似文献
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A high-repetition-rate femtosecond laser system operating, for the first time to our knowledge, in the spectral region near 200 nm is described. Frequency quadrupling of a mode-locked Ti:sapphire laser results in maximum average powers of 6 mW (165-fs pulses) and 15 mW (340-fs pulses) at 82 MHz. The shortest wavelength achieved is 193.7 nm. 相似文献
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孤子是自然界中一种基本的非线性波动传递形式,孤子间的相互作用能够映射出复杂非线性系统的多体动力学过程,具有重要的基础研究价值.被动锁模激光器是研究孤子相互作用的理想平台.光孤子之间的吸引、排斥作用能够形成孤子分子,而时间拉伸色散傅里叶变换(TS-DFT)技术使得实时探测孤子分子动力学成为可能.基于TS-DFT技术,本文实验研究了钛宝石飞秒激光器产生的孤子分子的内部动态,通过改变抽运功率,分别观察到了间隔为180 fs的稳定的孤子分子和间隔为105 fs的具有微弱相位振荡的孤子分子,后者的振动幅度仅为0.05 rad.实验发现受到环境影响,稳定态的孤子分子还能够转变为相位滑动状态.这些间隔为百飞秒量级的光学孤子分子对于研究孤子的近程非线性相互作用具有突出的意义. 相似文献
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Mengdi Qian Ye Dai Xiaona Yan Guohong Ma 《Applied Physics A: Materials Science & Processing》2014,114(4):1031-1037
We investigate the morphology change of Au film on sapphire substrate by irradiating with a 1 kHz femtosecond pulse laser. Under observation of a scanning electron microscope, a textured nanostructure was formed in the exposed area on Au film due to laser ablation and subsequent stress relaxation. This process was strongly determined by the laser intensity profile and the dynamics of molten liquid. With the increasing of laser pulses number, the Au film was broken down and then a few polarization-dependent nanoripples arranged in the same direction appeared on the sapphire surface, which may result from a spatial modulation of energy due to the interference between the incident light and the excited surface plasmon polaritons. In addition, we used an energy dispersive spectrometer to analyze the chemical composition of nanoripples on the surface and in the ablated crater, respectively. The changes of O and Al elements implied that a complicated chemical transformation participated in the nanoripples formation process. We believe that present results are very useful for the analysis of the interaction between femtosecond laser and solids, especially the film material. 相似文献