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1.
Stochastic numerical simulations are used to study the statistical properties of supercontinuum spectra generated in photonic
crystal fibre with two zero dispersion wavelengths. For picosecond pulse excitation, we examine how the statistical properties
of solitons generated on the long wavelength edge of the supercontinuum (``optical rogue waves") are modified by energy transfer
to dispersive waves across the second zero dispersion wavelength. The soliton statistics (characterized in terms of peak power,
wavelength and pulse duration) are shown to be strongly modified by the mechanism of dispersive wave generation, with the
detailed form of the probability distribution depending strongly on input pulse energy. 相似文献
2.
Simon Toft Sørensen Ole Bang Benjamin Wetzel John M. Dudley 《Optics Communications》2012,285(9):2451-2455
We show that the noise properties of fiber supercontinuum generation and the appearance of long-tailed “rogue wave” statistics can be accurately quantified using statistical higher-order central moments. Statistical measures of skew and kurtosis, as well as the coefficient of variation provide improved insight into the nature of spectral fluctuations across the supercontinuum and allow regions of long-tailed statistics to be clearly identified. These moments – that depend only on analyzing intensity fluctuations – provide a complementary tool to phase-dependent coherence measures to interpret supercontinuum noise. 相似文献
3.
This short editorial contains the introductory remarks for the special issue “discussions and debates” on the subject of “rogue
waves”. This issue is the first of its kind, in the sense that the authors have the chance to discuss the basic concepts of
an emerging topic in science. Based on these discussions, an attempt to give a “definition” of a rogue wave is made. 相似文献
4.
采用预测校正分步傅里叶方法数值模拟了飞秒光脉冲在光子晶体光纤中的非线性传输和超连续谱产生,分析了初始光脉冲的中心波长、峰值功率和光纤长度在光子晶体光纤正、反常色散区对超连续谱形状和带宽的影响。结果表明,当初始光脉冲的中心波长在光纤的反常色散区时,产生的超连续谱宽要远宽于正常色散区,但是光谱的平坦性较差;当光脉冲中心波长在靠近零色散波长的反常色散区且其他脉冲参数不变的情况下,存在一个产生宽且平坦的超连续谱的最佳峰值功率和最佳光纤长度。对于超连续谱系统的优化设计与实际应用具有参考意义。 相似文献
5.
A promising method for the generation of a supercontinuum with a high spectral power density based on the spectral broadening
of ultrashort pulses in a fiber amplifier is considered. The advantage of the method, as compared to the conventional way
of the supercontinuum generation in a microstructure fiber, is a lower pulse spectral broadening rate, which allows one to
achieve higher SC spectral power densities. The initial stage of the supercontinuum generation in an ytterbium fiber amplifier
(a fiber core diameter of 7 μm) with side pumping from an array of laser diodes with a total power of 8 W at a wavelength
of 976 nm is experimentally studied. Yb:KYW laser pulses with a duration of 250 fs, a central wavelength of 1046 nm, and an
average power of 150 mW have been supplied to the input of the amplifier. In this case spectrally broadened radiation with
an average spectral power density of higher than 65 mW/nm and a spectrum width of 50 nm has been obtained. 相似文献
6.
M. Rudolph A. Destexhe 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(1):125-132
Systems driven by Poisson-distributed quantal inputs can be described as
“shot noise” stochastic processes. This formalism can apply to neurons
which receive a large number of Poisson-distributed synaptic inputs of similar
quantal size. However, the presence of temporal correlations between these
inputs destroys their quantal nature, and such systems can no longer be
described by classical shot noise processes. Here, we show that explicit
expressions for various statistical properties, such as the amplitude
distribution and the power spectral density, can be deduced and investigated
as functions of the correlation between input channels. The monotonic behavior
of these expressions allows an one-to-one relation between temporal
correlations and the statistics of fluctuations. Multi-channel shot noise
processes, therefore, open a way to deduce correlations in input patterns by
analyzing fluctuations in experimental systems. We discuss applications such
as detecting correlations in networks of neurons from intracellular recordings
of single neurons. 相似文献
7.
实验研究了平顶激光光束经微透镜阵列在熔融石英中成丝的演化以及超连续辐射的产生,并进一步与高斯光束的成丝和超连续辐射进行了对比研究.分别对这两种光束的多丝传输进行了横向和纵向成像.结果表明,使用平顶光束可以获得更为均匀的多丝分布,成丝的起点也更为一致;尤其重要的是,相对于高斯光束,平顶光束可以使用更高的入射激光脉冲能量而不会造成介质的损伤,从而可以获得更高脉冲能量和更高转换效率的超连续辐射. 相似文献
8.
M. Kuperman D. Zanette 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):387-391
We analyze the phenomenon of stochastic resonance in an Ising-like system on a small-world network. The system, which is subject
to the combined action of noise and an external modulation, can be interpreted as a stylized model of opinion formation by
imitation under the effects of a “fashion wave”. Both the amplitude threshold for the detection of the external modulation
and the width of the stochastic-resonance peak show considerable variation as the randomness of the underlying small-world
network is changed.
Received 19 December 2001 相似文献
9.
We present a numerical study of the properties of picosecond supercontinuum (SC) generation when pumping in the normal dispersion region of photonic crystal fibers. Simulation results demonstrate that rogue wave generation can be reduced by adding a weak signal continuous-wave (CW) seed on the main pump pulse. Besides, the red-shifted part of SC exhibits higher degree of coherence and pulse-to-pulse intensity stability. 相似文献
10.
Generation of a compact high-power high-efficiency normal-dispersion pumping supercontinuum in silica photonic crystal fiber pumped with a 1064-nm picosecond pulse 下载免费PDF全文
Broadband normal dispersion pumping supercontinuum (SC) generation in silica photonic crystal fiber (PCF) is investigated in this paper. A 1064-nm picosecond fiber laser is used to pump silica PCF for the SC generation. The length of PCF is optimized for the most efficient stimulated Raman scattering process in the picosecond pump pulse region. The first stimulated Raman Stokes peak is located in the anomalous dispersion regime of the PCF and near the zero dispersion wavelength; thus the SC generation process can benefit from both a normal dispersion pumping scheme and an anomalous dispersion pumping scheme. The 51.7-W SC spanning from about 700 nm to beyond 1700 nm is generated with an all-fiber configuration, and the pump-to-SC conversion efficiency is up to 90%. In order to avoid the output fiber end face damage and increase the stability of the system, an improved output solution for the high power SC is proposed in our experiment. This high-efficiency near-infrared SC source is very suitable for applications in which average output power and spectral power density are firstly desirable. 相似文献
11.
Y.-Q. Liu J. Zhang Z. Jin Z.-Q. Hao Z. Zhang Z.-H. Wang 《Applied physics. B, Lasers and optics》2008,92(2):153-157
We present the spectral dynamics investigations of supercontinuum generation from 2.6 TW femtosecond laser pulses propagation
in air. The measured spectra in the supercontinuum channel show a large amount of oscillating structure, which is mostly contributed
from four-wave mixing, stimulated Raman scattering and the electronic mechanism self-phase modulation. The temporal coherence
length is almost the same as 0.45 ps for each spectral component with the same spectral width of supercontinuum that is confirmed
with a Michelson interferometer. The spatial coherence property of supercontinuum is measured by a Young’s double slit diffractometer,
which demonstrates that supercontinuum preserves a transverse coherence of about 144 μm because of the divergence of the supercontinuum
channel.
PACS 42.62.Fi; 42.68.Ay; 43.25.Jh 相似文献
12.
亚纳秒光脉冲抽运光子晶体光纤产生的瓦级超连续谱 总被引:1,自引:1,他引:0
研究了亚纳秒脉冲抽运光子晶体光纤产生高功率超连续谱的机理.采用掺镱锁模光纤激光器产生的脉宽570ps光脉冲,抽运1.8m光子晶体光纤,得到了平均功率为1.15W、光谱覆盖范围为750nm的超连续谱.通过实验和模拟结果的对比和分析,证实了亚纳秒脉冲抽运1.8m PCF产生超连续谱时,调制不稳定性效应起了重要作用.在研究了不同抽运功率下输出的超连续谱变化后,发现随着抽运功率的提高,输出功率也更高且超连续谱覆盖波段也更宽,在瓦级输出功率下依然未达到饱和展宽状态,还有进一步提高功率和展宽光谱的空间. 相似文献
13.
Z. Bak R. Jaroszewicz 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(2):231-235
A localized spin system of fractal symmetry with indirect exchange between them is considered. We define a specific class
of fractals as the “net fractals” which display multidimensional logarithmic periodicity. Basing on this property we model
the effective indirect exchange interaction by the conventional RKKY exchange with the logarithmic coordinates playing role
of the real space ones. Finally, we discuss the case of non-ideal “net fractals” in which fractional dynamics of the electrons
is expected. In this case we show that RKKY exchange integrals are given by the formulas derived under assumption that a system
has a fractional spectral dimension. 相似文献
14.
15.
The build-up of supercontinuum in a photonic crystal fiber (PCF) has been investigated experimentally as a function of pump power using chirped 100-fs pulses from a Ti:sapphire laser. As compared with the PCF at room temperature, a new blue-shifted spectral component is observed in the initial steps of supercontinuum (SC) generation when the central part of PCF is heated to 120 °C by a hot plate. In addition, the slope efficiency of SG is slightly improved with the slightly extension of supercontinuum spectrum in blue edge at high pump powers. The change in dispersion property as well as the effective cascading of nonlinear photonic crystal fibers for heated PCF would be the main attributions. 相似文献
16.
Darren D. Hudson Eric C. Mägi Alexander C. JudgeStephen A. Dekker Benjamin J. Eggleton 《Optics Communications》2012,285(23):4660-4669
In this review we consider the basic elements of tapering chalcogenide optical fibers for the generation of extreme spectral broadening through supercontinuum generation. Creating tapered nanofiber devices in chalcogenide fiber, which has an intrinsic nonlinearity that is two orders of magnitude higher than silica, has resulted in the demonstration of octave-spanning spectra using record low power. We first present a brief theoretical understanding of the tapering process that follows from the basic principle of mass conservation, and a geometric construction tool for the visualization of the shape of tapered fibers. This is followed by a theoretical treatment of dispersion engineering and supercontinuum generation in a chalcogenide nanofiber. In the final section, we cover the experimental implementation of the chalcogenide nanofiber and demonstrate an octave-spanning spectrum created with 150 W of peak power. 相似文献
17.
飞秒脉冲在熔石英玻璃中超连续谱产生的研究 总被引:1,自引:0,他引:1
从非线性薛定谔方程出发,利用分步傅里叶方法,研究了时空耦合飞秒脉冲在熔石英玻璃中传输时,传输距离、入射激光脉冲峰值功率、衍射、色散和非线性等因素对超连续谱产生的影响。结果表明,飞秒脉冲在熔石英玻璃中传输时,超连续谱的产生主要分为两阶段:由材料的自聚焦等三阶非线性效应引起的脉冲压缩阶段及由自相位调制和材料群速度色散引起脉冲分裂阶段。当高峰值功率的飞秒脉冲在熔石英玻璃中传输时,材料的三阶非线性效应抑制衍射效应,引起脉冲压缩,从而产生子脉冲,由此引入新的频率成分。同时,还研究了同一脉冲不同横向空间位置处的超连续谱的变化规律,在中心频率两侧均有新频率产生。最后,通过实验证实了超连续谱的产生。 相似文献
18.
N. M. Kachalova V. S. Voitsekhovich A. M. Borodin V. V. Khomenko S. Yu. Pentegov 《Optics and Spectroscopy》2011,111(4):593-598
Supercontinuum generation in the spectral range 530–1100 nm in series of photonic-crystal fibers pumped by femtosecond Ti:S laser Mira Oprima 900-F is achieved. The evolution of spectral characteristics of femtosecond supercontinuum is proofed to be dependent on pump pulse wavelength and power radiation. Polarization characteristics of supercontinuum spectral components are analyzed. We demonstrated experimentally the possibility of control of femtosecond supercontinuum generation. 相似文献
19.
An all-fiber supercontinuum generator with a record-high pulse energy of 40 μJ is presented. The generator is based on a nanosecond
ultralong high-energy mode-locked Yb-doped fiber laser with an additional amplification stage. The supercontinuum spectrum
belongs to the wavelength range 500–1750 nm, and a relatively uniform spectral distribution of the intensity is observed in
the interval 1125–1550 nm. The mean power of the supercontinuum is greater than 1.5 W. The simulation of such a generator
yields the integrity of the supercontinuum pulse on the nanosecond time scale and shows that the pulse can be characterized
by a certain energy in contrast to the multipulse complicated trains of supercontinuum corresponding to the femtosecond and
picosecond pumping. 相似文献
20.