共查询到20条相似文献,搜索用时 26 毫秒
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The well-known problem of the modulation instability of femtosecond light pulses propagating in a cubic nonlinear medium is considered on the basis of computer simulation with allowance made for the time dispersion of the nonlinear response. The dependence of the maximum perturbation frequency at which the instability takes place on the parameter characterizing the time dispersion of the nonlinearity is studied. The numerical experiments carried out verified the previous conclusion of the authors, based on an original approach to the analysis of propagation of a femtosecond pulse, that the frequency interval of the modulation instability can increase with increasing influence of the dispersion of the nonlinear response. This conclusion is at variance with the conclusion drawn by other researchers on the basis of linear analysis. 相似文献
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Spatially resolved amplitude and phase characterization of femtosecond optical pulses 总被引:5,自引:0,他引:5
Gallmann L Steinmeyer G Sutter DH Rupp T Iaconis C Walmsley IA Keller U 《Optics letters》2001,26(2):96-98
Ultrabroadband pulses exhibit a frequency-dependent mode size owing to the wavelength dependence of free-space diffraction. Additionally, rather complex lateral dependence of the temporal pulse shape has been reported for Kerr-lens mode-locked lasers and broadband amplifier chains and in frequency-domain pulse shapers, for example. We demonstrate an ultrashort-pulse characterization technique that reveals lateral pulse-shape variations by spatially resolved amplitude and phase measurements by use of spectral phase interferometry for direct electric-field reconstruction (SPIDER). Unlike with autocorrelation techniques, with SPIDER we can obtain spatially resolved pulse characterization even after the nonlinear process. Thus, with this method the spectral phase of the pulse can be resolved very rapidly along one lateral beam axis in a single measurement. 相似文献
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Controlling the carrier-envelope phase of ultrashort light pulses with optical parametric amplifiers
The phase link between signal, idler, and pump waves in a parametric interaction allows generation of an idler pulse with a phase independent of that of the input pulse. We suggest the use of a white-light seeded optical parametric amplifier as a self-stabilized source of few-cycle pulses, in which the phase of the electric field is exactly reproduced in each laser shot. 相似文献
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Shun-Jin Wang 《Zeitschrift für Physik B Condensed Matter》1994,96(1):97-103
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Georges H. Wagnière 《Optics Communications》2012,285(21-22):4344-4346
The proposition is made to fine-tune the phase of an unpolarized guided mode in a chiral optical waveguide, or fiber, by a static magnetic field applied in the direction of the light propagation. The core of the fiber should consist of randomly oriented chiral molecules, and the magnetic field-induced change of the refractive index would be due to the magnetochiral effect [1]. Although the magnetochiral birefringence is very small for magnetic field strengths obtainable under routine laboratory conditions, the induced phase shift for a given magnetic field should be maximized by increasing the pathlength of light inside the field. This would be technically achievable by winding the optical fiber axially many times around the electric solenoid that generates the magnetic field, in such a way that the path of the light inside the fiber follows closely and over a distance as long as possible the magnetic induction lines. 相似文献
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Amplitude and phase characterization of 4.5-fs pulses by frequency-resolved optical gating 总被引:1,自引:0,他引:1
The technique of second-harmonic generation frequency-resolved optical gating is applied to measure the intensity and the phase of 4.5-fs pulses resulting from the fiber-compressed output of a cavity-dumped Ti:sapphire laser. Characterization of even shorter optical pulses by this method should also be feasible. 相似文献
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We compare the cladding patterns present in grating structures fabricated with an ultrafast laser and a phase mask with a cw beam interference model. We find that the observed patterns agree well with the model results for picosecond pulses; however, for femtosecond pulses, we show that the full bandwidth and the pulsed nature of the sources must be considered because the pattern can be affected by group-velocity walk-off. An interesting consequence of order walk-off is the possibility of pure two-beam interference generation with a phase mask in the femtosecond pulse regime. 相似文献
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The mark-tracking method was used in the uniaxial tensile test to determine the elastic properties of optical fibers. The mark-tracking method is based on the follow-up of two markers on the specimen with the help of an image processing technique. It allows us to determine the true strain with respect to the small strains assumption (≤1%) or the finite strains (>1%) without any impact of the rigid solid movement or pulley fiber sliding on the measured strain. Both coated optical fiber and stripped fiber were subjected to the uniaxial tensile test and the cantilever beam bending test. The Young’ modulus results of the stripped fiber were found to be very similar for both tests. Thus, the mark-tracking method is adaptable to the tensile test of optical fibers and the elastic behaviors of both coated optical fiber and stripped fiber are found to be non-linear. Their Young's moduli are 22 and 79 GPa, respectively. These results revealed that those coatings play a mechanical role in fiber elongation. 相似文献
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光孤子脉冲在光纤放大器中的传播 总被引:2,自引:1,他引:2
本文建立了包括增益色散,受激喇曼散射,双光子吸收效应的理论模型,讨论了光孤子脉冲在光纤放大器中的传播.数值计算结果表明:在反常色散范围内,光孤子的放大是不稳定的.增益色散导致光脉冲对称分裂,而受激喇曼散射则导致不对称的分裂.在增益色散和受激喇曼散射的共同作用下可获得新的时域和频域特征.有限带宽的放大能抑制受激喇曼散射引起的自频移.本文对有啁啾的光孤子脉冲的放大也进行了分析. 相似文献
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An interferometric method is presented to characterize the most important parameters of beams from large aperture femtosecond excimer laser systems. With the use of a special interferometer the shape of both the pulse and the phase fronts can simultaneously be studied. With minor changes, conventional autocorrelation measurements can also be performed. 相似文献
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Apolonski A Poppe A Tempea G Spielmann C Udem T Holzwarth R Hansch TW Krausz F 《Physical review letters》2000,85(4):740-743
Using a coherent nonlinear optical technique, slipping of the carrier through the envelope of 6-fs light wave packets emitted from a mode-locked-oscillator/pulse-compressor system has been measured, permitting the generation of intense, few-cycle light with precisely reproducible electric and magnetic fields. These pulses open the way to controlling the evolution of strong-field interactions on the time scale of the light oscillation cycle and are indispensable to reproducible attosecond x-ray pulse generation. 相似文献
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López-Martens R Varjú K Johnsson P Mauritsson J Mairesse Y Salières P Gaarde MB Schafer KJ Persson A Svanberg S Wahlström CG L'huillier A 《Physical review letters》2005,94(3):033001
We report the generation, compression, and delivery on target of ultrashort extreme-ultraviolet light pulses using external amplitude and phase control. Broadband harmonic radiation is first generated by focusing an infrared laser with a carefully chosen intensity into a gas cell containing argon atoms. The emitted light then goes through a hard aperture and a thin aluminum filter that selects a 30-eV bandwidth around a 30-eV photon energy and synchronizes all of the components, thereby enabling the formation of a train of almost Fourier-transform-limited single-cycle 170 attosecond pulses. Our experiment demonstrates a practical method for synthesizing and controlling attosecond waveforms. 相似文献
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Modified optical Bloch equations for two-level atoms in the radiation field with the complex polarization vector, the complex amplitude, and the complex wave vector are derived. A specific case is considered in which a field of this kind acts on a separate atom of a nonlocal atomic system. The solution of the modified equations for the interaction of atoms with ultrashort light pulses is obtained. 相似文献
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The conditions for forming pulses with parabolic envelope asymptotics in inhomogeneous fiber optical amplifiers are investigated. The profile of normal group-velocity dispersion, which ensures formation of parabolic pulses with a reduced rate of frequency modulation, is determined. It is shown by numerical simulation that the presence of chirp in the input pulse may cause narrowing of the spectrum at a certain energy. 相似文献
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光导纤维中光速的实验测定 总被引:7,自引:4,他引:3
介绍了光导纤维中光速测定的基本原理。采用调制信号,应用门电路测量了两路输入信号的相差,计算出调制信号在光导纤维中的传输时间,从而得到光速。 相似文献
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《Comptes Rendus de l''Academie des Sciences Series IV Physics》2001,2(10):1415-1426
The complete characterization of a short light pulse requires the measurement of the value of the electric field as a function of time, or conversely, as a function of the optical frequency. Many different techniques have been demonstrated for this purpose. They fall in two main categories, whether a known reference pulse whose spectrum encompasses that of the unknown pulse is available or not. In the first case, linear techniques such as time-domain or frequency-domain interferometry can be directly used, with the advantage of a high sensitivity. In the latter case, non-stationary filters can be implemented using optical non-linearities, in techniques such as Frequency Resolved Optical Gating (FROG) or Spectral Phase Interferometry for Direct Electric-field Reconstruction (SPIDER). 相似文献
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Self-similarity techniques are used to study pulse propagation in a normal-dispersion optical fiber amplifier with an arbitrary longitudinal gain profile. Analysis of the nonlinear Schr?dinger equation that describes such an amplifier leads to an exact solution in the high-power limit that corresponds to a linearly chirped parabolic pulse. The self-similar scaling of the propagating pulse in the amplifier is found to be determined by the functional form of the gain profile, and the solution is confirmed by numerical simulations. The implications for achieving chirp-free pulses after compression of the amplifier output are discussed. 相似文献
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Asymptotic characteristics of parabolic similariton pulses in optical fiber amplifiers 总被引:3,自引:0,他引:3
The fundamental asymptotic nature of parabolic similariton pulses in normal-dispersion fiber amplifiers is experimentally demonstrated. With frequency-resolved optical gating characterization measurements with a fixed input pulse energy, the output parabolic pulse characteristics are shown to be invariant with the input pulse profile and duration and to be completely determined only by the amplifier parameters. 相似文献