共查询到20条相似文献,搜索用时 0 毫秒
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Dongqing Pang Yunxuan Li Qingyue Wang 《Applied Physics A: Materials Science & Processing》2014,115(4):1181-1185
Resonant ablation is beneficial to avoiding uncontrollable subsurface damages in the laser ablation of polymers. In this paper the dynamics of mid-infrared laser resonant ablation of polylactic acid and toluene was calculated by using fluid dynamic equations. The merits and drawbacks of mid-infrared femtosecond laser resonant ablation of high molecular weight polymers have been discussed. 相似文献
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We discuss a dual-stage optical parametric chirped-pulse amplifier generating sub-100-fs pulses in the mid-infrared at a repetition rate of 100 kHz. The system is based on a 1064 nm pump laser and a 3–4 μm difference frequency generation seed source derived from the output of a femtosecond fiber laser amplifier. Both lasers are commercially available, are diode-pumped, compact, and allow for turn-key operation. Here, we focus our discussion on the design and dimensioning of the optical parametric chirped-pulse amplifier. In particular, we review the available gain materials for mid-infrared generation and analyze the impact of different stretching scenarios. Timing jitter plays an important role in short-pulse parametric amplifier systems and is therefore studied in detail. The geometry of the amplifier stages is optimized through a full 3-dimensional simulation with the aim of maximizing gain bandwidth and output power. The optimized system yields output pulse energies exceeding 1 μJ and an overall gain larger than 50 dB. The high repetition rate of the pump laser results in an unprecedented average power from a femtosecond parametric system at mid-infrared wavelengths. First experimental results confirm the design and the predictions of our theoretical model. 相似文献
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We present a scheme to produce programmable phase- and amplitude-modulated femtosecond laser pulses in the mid-infrared regime of 3-10mum by difference frequency mixing. The 80-fs signal output of an optical parametric amplifier is shaped with a liquid-crystal mask and mixed in an AgGaS(2) crystal with a temporally stretched idler pulse. Without changing the mechanical alignment, we produce programmable amplitude modulations and chirped pulses at lambda=3mum with energy as high has thas 1muJ . This scheme, further, allows the generation of controllable pulse sequences. The results are in good agreement with theoretical simulations. 相似文献
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A recent experiment [Appl. Phys. Lett. 83, 213 (2003)] indicated that filaments created in femtosecond high-power pulses propagating in air are surprisingly robust when interacting with microscopic water droplets. We present numerical modeling of the dynamics of the filament-droplet interaction. Our simulation results provide further insight into the interplay between the filament's core and the wide transverse pedestal of the pulse. It is shown that the robustness of the filament comes from the transverse low-intensity pedestal that controls the formation of the central hot spot. Implications for penetration of wide, high-power beams through obscurants are discussed. 相似文献
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Inscription of optical waveguides in crystalline silicon by mid-infrared femtosecond laser pulses 总被引:1,自引:0,他引:1
Nejadmalayeri AH Herman PR Burghoff J Will M Nolte S Tünnermann A 《Optics letters》2005,30(9):964-966
For the first time to the authors' knowledge, optical waveguides have been inscribed in bulk crystalline silicon by ultrafast laser radiation. Femtosecond laser pulses of 40-nm spectral bandwidth, 1-kHz repetition rate, and 1.7-microJ on-target energy were applied at a mid-infrared wavelength of 2.4 microm to induce nonlinear absorption in the focal volume of the beam. By scanning the laser beam with respect to the sample, buried optical waveguides have been created that were single mode at 1550 and 1320 nm and guided light only with its polarization perpendicular to the sample's surface. Propagation losses with an upper limit of 1.2 dB/cm or less were observed throughout the optical telecommunications band. 相似文献
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Tunable mid-infrared pulses are generated with a MgO:LiNbO3-based traveling-wave optical parametric amplifier in single and double stage operation regime pumped by a 1-kHz Ti:sapphire regenerative amplifier system. For the first time to our knowledge a pulsed laser diode is successfully used in the femtosecond regime as a compact seed source at the signal wavelength where the tunability of the generated idler pulses can be realized by tuning the seed wavelength. Almost transform limited mid-infrared pulses as short as 130 and 160 fs with pulse energies as high as 5 and 15 J are produced near 3.5 m by the single and double stage scheme, respectively. The pulse to pulse fluctuations in both cases do not exceed 2% which corresponds to the stability of the pump source. 相似文献
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The techniques of coupled-cavity modelocking and self-modelocking in which intensity-induced nonlinear effects are exploited have been reviewed for broad-band gain media. Particular emphases have been placed upon the archetypical colour-centre and titanium-sapphire laser configurations in which these techniques were first demonstrated and subsequent refinements are set in context. A femtosecond optical parametric oscillator pumped by a self-mode-locked titanium-sapphire laser has also been described as an exemplar of a practical means of extending the source tunability into the mid-infrared spectral region. 相似文献
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Sources of noise present in swirl burners in the non-combustive and combustive cases are experimentally investigated. It is shown that under the non-combustive conditions, the main source of noise is the precessing vortex core, a three-dimensional time-dependent instability present in such burners at high degrees of swirl. With combustion, the amplitude of this instability is damped and the combustion roar is predominant. Regimes of noise (combustion roar) generation in a flame can be located by measurements of temperature fluctuations, as it is demonstrated that there is a good correlation with pressure fluctuations. 相似文献
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T. Imahoko K. Takasago T. Sumiyoshi H. Sekita K. Takahashi M. Obara 《Applied physics. B, Lasers and optics》2007,87(4):629-634
We have developed a 6–12 μm mid-infrared (MIR) femtosecond laser source for glyco-protein structure analysis. The MIR femtosecond
laser pulses are generated by a differential frequency generation (DFG) configuration with a combination of Ti:sapphire based
regeneratively amplified femtosecond laser pulses (780 nm, 160 fs, 1 mJ) and a β-BaB2O4 (BBO) based optical parametric amplifier (OPA). The MIR pulse energy exceeds 4.5 μJ, where a glyco-protein molecule has resonant
absorption lines due to the vibrational–rotational transitions. The pulse width is estimated to be less than 1 ps according
to the cross correlation measurement between the two OPA output pulses. Using the MIR femtosecond laser pulses, we demonstrated
photo-dissociation of the sialyl Lewis X (sLeX) proton added ion, which is the first time to the best of our knowledge.
PACS 42.65.Re; 42.62.-b; 42.60.-b; 42.65.-k; 87.50 相似文献
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Mid-infrared ultrashort pulses of 9.2-microm center wavelength are characterized in both amplitude and phase. This is achieved by use of a variant of spectral phase interferometry for direct electric field reconstruction in which spectral interferometry has been replaced with time-domain interferometry, a technique that is well suited for infrared pulses. The setup permits simultaneous recording of the second-order interferometric autocorrelation, thus providing an independent check on the retrieved spectral phase. 相似文献
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We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail. 相似文献
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I.P. Christov 《Optics Communications》1985,53(6):364-366
Femtosecond transform limited light pulse propagation in vacuum is described in scalar approximation of diffraction theory. Evolution of the spatial and temporal characteristics of the pulse are presented. 相似文献
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Weidong Chen Julien Cousin Emmanuelle Poullet Jean Burie Daniel Boucher Xiaoming Gao Markus W. Sigrist Frank K. Tittel 《Comptes Rendus Physique》2007,8(10):1129-1150
We report on recent developments of widely tunable, continuous-wave (CW) laser sources based on difference-frequency generation (DFG) in nonlinear optical materials. The state-of-the-art of CW DFG technology will be reviewed. Applications of the DFG-based laser source to high-resolution molecular spectroscopy and trace gas detection will be presented. New development trends of DFG will be discussed. To cite this article: W. Chen et al., C. R. Physique 8 (2007). 相似文献
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Maksimenka R Nuernberger P Lee KF Bonvalet A Milkiewicz J Barta C Klima M Oksenhendler T Tournois P Kaplan D Joffre M 《Optics letters》2010,35(21):3565-3567
Direct amplitude and phase shaping of mid-infrared femtosecond pulses is realized with a calomel-based acousto-optic programmable dispersive filter transparent between 0.4 and 20 μm. The shaped pulse electric field is fully characterized with high accuracy, using chirped-pulse upconversion and time-encoded arrangement spectral phase interferometry for direct electric field reconstruction techniques. Complex mid-infrared pulse shapes at a center wavelength of 4.9 μm are generated with a spectral resolution of 14 cm(-1), which exceeds by a factor of 5 the reported experimental resolutions of calomel-based filters. 相似文献
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