共查询到20条相似文献,搜索用时 15 毫秒
1.
Xiaowei Chen Yuxin Leng Jun Liu Yi Zhu Ruxin Li Zhizhan Xu 《Optics Communications》2006,259(1):331-335
We experimentally demonstrate that high-power femtosecond pulses can be compressed during the nonlinear propagation in the normally dispersive solid bulk medium. The self-compression behavior was detailedly investigated under a variety of experimental conditions, and the temporal and spectral characteristics of resulted pulses were found to be significantly affected by the input pulse intensity, with higher intensity corresponding to shorter compressed pulses. By passing through a piece of BK7 glass, a self-compression from 50 to 20 fs was achieved, with a compression factor of about 2.5. However, the output pulse was observed to be split into two peaks when the input intensity is high enough to generate supercontinuum and conical emission. 相似文献
2.
M. Nisoli G. Sansone S. Stagira C. Vozzi S. De Silvestri O. Svelto 《Applied physics. B, Lasers and optics》2002,75(6-7):601-604
A novel spectral broadening technique, based on hollow-fiber cascading, is reported, which allows the generation of a supercontinuum
extending to a bandwidth exceeding 510 THz with excellent spatial beam quality. High-peak-power, sub-7-fs light pulses tunable
from the visible to the near infrared have been generated by compression of portions of the supercontinuum, employing different
sets of chirped mirrors.
Received: 11 July 2002 / Revised version: 3 September 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +39-02/2399-6126, E-mail: mauro.nisoli@fisi.polimi.it 相似文献
3.
Xianglong Zeng Satoshi Ashihara Xianfeng Chen Kazuo Kuroda 《Optics Communications》2008,281(17):4499-4503
We experimentally demonstrate engineerable compression of two-colored pulses in a linearly-chirped quasi-phase-matching grating. Quadratic solitons generated from fundamental input are reshaped through cascaded parametric processes of second-harmonic generation (SHG) and the back-conversion. We use type-I (e: o + o) SHG geometry in a 50-mm-long aperiodically-poled MgO:LiNbO3 device to satisfy the group-velocity matching condition. Simultaneously compressed fundamental and SH pulses of about 55-fs duration with small pedestal are generated from the fundamental input pulses of 95-fs duration. 相似文献
4.
Flat Supercontinuum Generation at 1550 nm in a Dispersion-Flattened Microstructure Fibre Using Picosecond Pulse
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The generation of a flat supercontinuum of over 80nm in the 1550nm region by injecting 1.6ps 10 GHz repetition rate optical pulses into an 80-m-long dispersion-flattened microstructure fibre is demonstrated. The fibre has small normal dispersion with a variation smaller than 1.5 (ps·nm^-1·km^-1) between 1500 and 1650nm. The generated supercontinuum ranging from 1513 to 1591 nm has the flatness of ±1.5 dB and it is not so flat in the range of several nanometres around the pump wavelength 1552nm. Numerical simulation is also used to study the effect of optical loss, fibre parameters and pumping conditions on supercontinuum generation in the dispersion-flattened microstructure fibre, and can be used for further optimization to generate flat broad spectra. 相似文献
5.
Ambika Nautiyal 《Optics Communications》2007,278(1):175-179
The white light continuum (WLC) generated in water/D2O mixture by pumping with the fundamental of ps Nd+3:YAG laser has been used as a variable frequency source for the sum frequency generation as well as for its amplification. 35 ps long pulses with 8 mJ energy at 1064 nm were mixed collinearly with the WLC generated by the same laser beam in a 20 mm thick BBO crystal. The obtained tunable output has been identified as the sum frequency between the fundamental and a portion of the WLC with the required phase matching. Theoretical simulations are also given along with a few initial experiments to use this combination for the difference frequency generation (optical parametric amplification) under non-collinear geometry. 相似文献
6.
Shian Zhang Xiangyun Zhang Jianhua Huang Li Deng Zhenrong Sun Weiping Zhang Zugeng Wang Zhizhan Xu 《Optics Communications》2007,271(2):559-563
An optimal feedback control of broadband frequency up-conversion in BBO crystal is experimentally demonstrated by shaping femtosecond laser pulses based on genetic algorithm, and the frequency up-conversion efficiency can be enhanced by ∼16%. SPIDER results show that the optimal laser pulses have shorter pulse-width with the little negative chirp than the original pulse with the little positive chirp. By modulating the fundamental spectral phase with periodic square distribution on SLM-256, the frequency up-conversion can be effectively controlled by the factor of about 17%. The experimental results indicate that the broadband frequency up-conversion efficiency is related to both of second harmonic generation (SHG) and sum frequency generation (SFG), where the former depends on the fundamental pulse intensity, and the latter depends on not only the fundamental pulse intensity but also the fundamental pulse spectral phase. 相似文献
7.
色散平坦渐减光纤中超连续谱的产生 总被引:2,自引:1,他引:1
对双正交偏振光脉冲在色散平坦渐减光纤中传输时超连续谱的产生进行了计算和分析。结果表明,由于交叉相位调制效应的作用,双光脉冲可以产生比单光脉冲明显展宽且更为平坦的超连续谱。对于双基孤子脉冲,可以得到-20dB谱宽达388nm的平坦宽带超连续谱,比单基孤子脉冲产生的超连续谱谱宽增加72nm,交叉相位调制效应对超连续谱的产生起到增强的效果。当输入脉冲的抽运功率较低时,交叉相位调制效应对超连续谱的产生的增强效果更为显著,它极大地提高了超连续谱的产生的效率。数值计算的结果还表明,与其他高阶非线性效应相比,拉曼自频率移效应对超连续谱产生的影响更为明显。 相似文献
8.
Supercontinuum generation by femtosecond filaments in air is investigated for different laser wavelengths ranging from ultraviolet to infrared. Particular attention is paid on the role of third-harmonic generation and temporal steepening effects, which enlarge the blue part of the spectrum. A unidirectional pulse propagation model and nonlinear evolution equations are numerically integrated and their results are compared. Apart from the choice of the central wavelength, we emphasize the importance of the clamped intensity reached by self-guided pulses, together with their temporal duration and propagation length as key players acting on both supercontinuum generation of the pump wave and emergence of the third harmonic. Maximal broadening is observed for large wavelengths and long filamentation ranges. 相似文献
9.
A.V. Mitrofanov A.A. Ivanov M.V. Alfimov A.A. Podshivalov A.M. Zheltikov 《Optics Communications》2007,280(2):453-456
Microjoule supercontinuum generation is demonstrated using a large-mode-area photonic-crystal fiber (PCF) pumped by an amplified stretched-pulse output of a mode-locked Cr:forsterite laser. A PCF with a mode area of 380 μm2 is employed to transform 300-fs Cr:forsterite laser pulses with a peak-power of a few megawatts into a supercontinuum radiation with a spectrum spanning from 700 to 1800 nm and a total energy of 1.15 μJ. 相似文献
10.
Supercontinuum Gneneration and Modes Analysis in Secondary Cores of a Hollow-Core Photonic Crystal Fiber
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We demonstrate the generation of supercontinuum spectra in three secondary cores of a hollow-core photonic crystal fiber pumped by femtosecond laser pulses, respectively. The supercontinuum spectra are mainly a result of the soliton self-frequency shift and an amplification of dispersive wave at visible wavelengths. Detailed mode simulations show that with the increasing core length, the modes transfer from "double-points" to "single-point" since the pump laser is more easily coupled into the two side cores of a secondary core when the core length is small. The simulation results also explain why the experimental observed far-field beam patterns of first two secondary cores are different. 相似文献
11.
Yang H Zhang J Zhang Q Hao Z Li Y Zheng Z Wang Z Dong Q Lu X Wei Z Sheng Z Yu J Yu W 《Optics letters》2005,30(5):534-536
We investigate polarization-dependent properties of the supercontinuum emission generated from filaments produced by intense femtosecond laser pulses propagating through air over a long distance. The conversion efficiency from the 800-nm fundamental to white light is observed to be higher for circular polarization than for linear polarization when the laser intensity exceeds the threshold of the breakdown of air. 相似文献
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14.
O. Steinkellner M. Wittmann G. Korn I.V. Hertel 《Applied physics. B, Lasers and optics》2001,73(3):279-281
We use sub-10-fs pulses at 400 nm and 15-fs pulses at 800 nm to ionize water molecules and their isotopomers HDO and D2O in a pump–probe scheme. Pulses are generated via spectral broadening of 25-fs pulses of a 1-kHz Ti:sapphire amplifier system
by self-phase modulation in a noble-gas-filled hollow waveguide and subsequent compression using chirped mirrors. At this
time scale vibronic excitation of the first bending mode of water in the electronic ground state by impulsive Raman scattering
is possible (e.g. the fundamental bending mode of H2O: tvib=20 fs). The effect of this pre-excitation on the ionization rate is shown.
Received: 14 May 2001 / Revised version: 24 August 2001 / Published online: 19 September 2001 相似文献
15.
An acoustic-optics programmable dispersive filter (AOPDF) was first employed to actively control the linearly polarized femtosecond pump pulse frequency chirp for supercontinuum (SC) generation in a high birefringence photonic crystal fiber (PCF). By accurately controlling the second order phase distortion and polarization direction of incident pulses, the output SC spectrum can be tuned to various spectral energy distributions and bandwidths. The pump pulse energy and bandwidth are preserved in our experiment. It is found that SC with broader bandwidth can be generated with positive chirped pump pulses except when the chirp value is larger than the optimal value, and the same optimal value exists for the pump pulses polarized along the two principal axes. With optimal positive chirp, more than 78% of the pump energy can be transferred to below 750 nm. Otherwise, negative chirp will weaken the blue-shift broadening and the SC bandwidth. 相似文献
16.
In this paper, the multi-stage compression of picosecond pulses by cascaded quadratic nonlinearity is studied theoretically, and the dependence of pulse compression on phase-mismatch, laser intensity, and crystal characteristics has been discussed in detail. We demonstrate that the multi-stage pulse compression is much more efficient than the single-stage with a same total crystal length. Pulses as short as ∼150 fs can be generated by compressing 30-ps initial pulses in a two-stage configuration under the realistic crystal and laser conditions, and shorter pulses of ∼30 fs may be obtained by three-stage compression. Pulse compression performances with BiBO and BBO crystals are compared and discussed finally. 相似文献
17.
Numerical simulations are used to study how fiber supercontinuum generation seeded by picosecond pulses can be actively controlled
through the use of input pulse modulation. By carrying out multiple simulations in the presence of noise, we show how tailored
supercontinuum spectra with increased bandwidth and improved stability can be generated using an input envelope modulation
of appropriate frequency and depth. The results are discussed in terms of the nonlinear propagation dynamics and pump depletion. 相似文献
18.
The signal and idler output of an optical parametric oscillator are mixed in LiIO3 and AgGaS2 crystals to generate infrared pulses with a repetition rate of 82 MHz and an average power of 500µW. The infrared pulses are tunable between 2.5 and 5.5 µm, have a duration of 200 fs and a peak-to-peak intensity fluctuation of less than 5 %. 相似文献
19.
The critical intensity inside plasma filaments generated in air by high-power, ultra-short laser pulses is estimated analytically
and compared to recent experimental data. The result, Icrit≈4×1013 W/cm2, is highly relevant for atmospheric applications.
Received 18 August 2000 / Published online: 8 November 2000 相似文献
20.
Shifeng Du Dongxiang Zhang Baohua Feng Jing-Yuan Zhang Jing-Cun Zang 《Optics Communications》2009,282(14):2960-12186
We report the generation of high-peak power multi-wavelength picosecond laser pulses using optical parametric amplification (OPA) in BBO seeded with pulses generated in a 5-mm length BaWO4 crystal by stimulated Raman scattering of 18-ps laser pulses at 532 nm. The maximum output energy of the amplified first-Stokes component at 559.7 nm was about 1.76 mJ. The corresponding maximum peak power, pulse duration and spectral line width were measured to be 117.3 MW, 15 ps and 18.0 cm−1, respectively. The multi-wavelength picosecond laser pulses were in the visible and near infrared ranges. Using this Raman-seeded OPA technique, the beam quality of the stimulated Raman scattering pulses can be improved. 相似文献