共查询到20条相似文献,搜索用时 0 毫秒
1.
利用非线性薛定谔方程对飞秒脉冲在硅波导中的传输以及超连续谱的产生进行了研究,计算和分析了色散参量及非线性损耗在超连续谱的产生过程中的影响.结果表明,孤子分裂是飞秒脉冲在硅波导中产生超连续谱的主要机理.飞秒脉冲中心波长与波导零色散点的相对位置对超连续谱的产生有极大影响.当中心波长位于近零色散点的反常色散区时,孤子分裂现象最明显,谱宽远大于在零色散波长及正常色散处入射时的情况,并且达到稳定展宽所需波导长度最短.其次,高阶色散的大小也会影响光谱展宽,三阶色散绝对值较小时,能够获得较大的展宽.另外,由于双光子吸收效应带来大量损耗,限制了谱宽,并且随着初始脉冲功率的逐渐增大,展宽出现饱和现象.
关键词:
超连续谱
孤子分裂
色散
硅波导 相似文献
2.
The interactions between coherent beams launched near the interface of one-dimensional semi-infinite Kerr-type nonlinear waveguide arrays have been theoretically investigated. We have explored the effect of the input intensities, the relative phase of the optical beams, and the modulation of the refractive index of the optical lattices on nonlinear beam interaction dynamics. For in-phase beams with different incident intensities, the highly-localized spatial soliton was dragged in a discrete fashion by a low-intensity diffracting beam. Anomalous fusion of two out-of-phase beams, and energy exchange between the excited channels were observed at high intensities. The possibility of employing nonlinear interactions for optical signal re-addressing, all-optical switching is also discussed. 相似文献
3.
Meier J Stegeman GI Silberberg Y Morandotti R Aitchison JS 《Physical review letters》2004,93(9):093903
We report our investigation of Kerr nonlinear beam interactions in discrete systems. The influence of power and the relative phase between two Gaussian shaped beams was investigated in detail by performing numerical simulations of the discrete nonlinear Schr?dinger equation and comparing the results with experiments done in AlGaAs waveguide arrays. Good agreement between theory and experiment was obtained. 相似文献
4.
Khomeriki R 《Physical review letters》2004,92(6):063905
The effect of nonlinear transmission in coupled optical waveguide arrays is theoretically investigated and a realistic experimental setup is suggested. The beam is injected in a single boundary waveguide, linear refractive index of which (n(0)) is larger than refractive indexes (n) of other identical waveguides in the array. Particularly, the effect holds if omega(n(0)-n)/c>2Q, where Q is a linear coupling constant between array waveguides, omega is a carrier wave frequency, and c is a light velocity. Numerical experiments show that the energy transfers from the boundary waveguide to the waveguide array above a certain threshold intensity of the injected beam. This effect is due to the creation and the propagation of gap solitons in full analogy with a similar phenomenon in sine-Gordon lattice [Phys. Rev. Lett. 89, 134102 (2002)]]. 相似文献
5.
We study light localization at a phase-slip defect created by two semi-infinite mismatched identical arrays of coupled optical waveguides. We demonstrate that the nonlinear defect modes possess the specific properties of both nonlinear surface modes and discrete solitons. We analyze the stability of the localized modes and their generation in both linear and nonlinear regimes. 相似文献
6.
F. Setzpfandt D. N. Neshev A. A. Sukhorukov R. Schiek R. Ricken Y. Min Y. S. Kivshar W. Sohler F. Lederer A. T��nnermann T. Pertsch 《Applied physics. B, Lasers and optics》2011,104(3):487-493
We present theoretical and experimental studies on nonlinear beam propagation in lithium niobate waveguide arrays utilizing higher-order second harmonic bands. We find that the implementation of the higher-order second harmonic bands leads to a number of new effects. The combined interaction of two second harmonic bands with a propagating fundamental beam can lead to a complete inhibition of nonlinear effects or to the formation of discrete spatial solitons, depending only on the wavelength of the fundamental wave. Furthermore we analyze the properties of discrete solitons, allowing for linear coupling of the second harmonic. Here we predict and demonstrate experimentally a power dependent phase transition of the soliton topology. 相似文献
7.
Nonlinear optical studies in semiconductor-doped glasses (SDGs) are performed under femtosecond laser pulse excitation. Z-scan
experiments with 800 nm wavelength pulses are used to excite SDG samples in the resonance and non-resonance regimes. Schott
colour glass filter OG 515 shows stronger two-photon absorption than GG 420 and both the samples exhibit positive nonlinearity.
However, in resonantly excited RG 850 the intensity-dependent Z-scan shows transition from saturable to reverse saturable
absorption behaviour with the increase in intensity. 相似文献
8.
Optical waveguide arrays induced in fused silica by void-like defects using femtosecond laser pulses
C. Méndez J.R. Vázquez de Aldana G.A. Torchia L. Roso 《Applied physics. B, Lasers and optics》2007,86(2):343-346
We report a new approach to the microfabrication of permanent optical waveguide arrays inside fused silica induced by focusing
infrared femtosecond laser pulses with microjoule energy. These arrays consist of waveguides limited by void-like damage zones
with very loose coupling among adjacent guides, thus allowing the excitation of a single one. The proposed method shows the
possibility of using created void-like structures for both the fabrication of integrated optical devices as well as for the
control of previously induced refractive index change regions.
PACS 42.65.Re; 42.82.Et; 42.79.-e 相似文献
9.
D.E. Leaird A.M. Weiner S. Shen A. Sugita S. Kamei M. Ishii K. Okamoto 《Optical and Quantum Electronics》2001,33(7-10):811-826
For the application of high repetition rate wavelength division multiplexed (WDM) pulse train generation from a femtosecond modelocked fiber laser, the direct space-to-time pulse shaper and a properly designed arrayed waveguide grating (AWG) are equivalent. The analogy between the bulk optics and integrated configuration is explored for this application. The critical design parameters of the AWG are the free spectral range and the pathlength difference between adjacent guides in the array. 相似文献
10.
We present a theoretical investigation of the self-focusing dynamics of femtosecond pulses in a hollow waveguide. We show that transverse effects play an important role in these dynamics, even for pulses that are significantly below the critical power for self-focusing in free space, and that excitation of higher-order modes of the waveguide results in the spreading of the pulse in time. Inclusion of self-steepening and space-time focusing in our model is necessary for properly capturing the pulse dynamics. 相似文献
11.
The paper deals with the theoretical investigation of ultrafast-pulse evolution in a semiconductor quantum well (QW). Semiconductor Bloch equations are used to obtain the polarization induced in the medium due to incident Gaussian electromagnetic beam. The partial differential equation with finite group velocity dispersion (GVD) is then used to analyze the effect of induced polarization on the pulse. The role of GVD on femtosecond pulse evolution in GaAs/AlGaAs waveguide is studied, giving due consideration to the intensity dependent group velocity of the medium. 相似文献
12.
13.
E. M. Dianov A. B. Grudinin D. V. Khaidarov D. V. Korobkin A. M. Prokhorov V. N. Serkin 《Fiber and Integrated Optics》2013,32(1):61-69
At the cascade SRS in the region of negative chromatic dispersion of a single mode fiber, 70-to 100-fs light pulses have been obtained. It is shown that a 70-fs multisoliton pulse in a single mode fiber breaks up into “color” solitons. Pulses of 18 fs have been formed by multisoliton compression. The pulse duration corresponds to about three optical cycles at the wavelength of 1.6 μm. From the results of the experiment, the relaxation time of the silica-glass electron nonlinearity is estimated to be 2 to 4 fs. 相似文献
14.
We demonstrated the spectrally narrowed laser emission from all-plastic organic waveguide with the distributed feedback (DFB) resonator pumped by Ti-sapphire femtosecond laser. We fabricated the DFB resonator on a surface of a photoresist polymer using an interference of laser beams. All-plastic waveguide with organic dyes dispersed in poly(N-vinylcarbazole) and polystyrene matrix was spin-coated on a DFB resonator. Very narrow full width at half maximum (FWHM) of 0.15 nm in emission wavelength was observed, whereas an excitation laser of Ti-sapphire femtosecond laser has broad FWHM of 14 nm. 相似文献
15.
16.
Bright and dark spatial gap solitons are demonstrated in waveguide arrays. These gap solitons travel across the array at zero transverse velocity, in complete analogy with stationary (immobile) temporal gap solitons. Furthermore, the launching configuration for observing these stationary gap solitons is shown to be the analog of an "ideal experiment" for observing stationary temporal gap solitons, never observed so far. A clear distinction is established between the family of Floquet-Bloch solitons in general and discrete solitons in particular, and the limiting case of gap solitons. 相似文献
17.
A device consisting of a cascaded semiconductor optical amplifier (SOA) and silicon on insulator (SOI) optical waveguide is presented to amplify and reshape the frequency spectrum of optical pulses in the picoseconds time duration. Numerical simulations show that the output spectrum of the amplified pulse by SOA can be effectively reshaped by utilizing the SOI waveguide. The length of the SOI waveguide may be judiciously adjusted to significantly reduce the frequency chirp of the output pulse from the SOA resulting in reshaping of the output spectrum. We find that the property of pulse spectrum is sensitive to the input pulse power and its temporal width. 相似文献
18.
T. Brixner A. Oehrlein M. Strehle G. Gerber 《Applied physics. B, Lasers and optics》2000,70(7):S119-S124
We describe the experimental implementation of feedback-optimized femtosecond laser pulse shaping. A frequency-domain phase shaper is combined with different pulse characterization methods and appropriate optimization algorithms to compensate for any phase deviation. In particular, bandwidth-limited, amplified laser pulses are achieved by maximizing the second-harmonic generation (SHG) of the shaped laser pulses with the aid of an evolutionary algorithm. Real-time measurement of the absolute phases is achieved with spectral interferometry where the reference pulse is characterized by FROG, the so-called TADPOLE method. Using the complete electric field as feedback, arbitrary laser pulse shapes can be optimally generated in two different ways. First, a local convergence algorithm can be used to apply reliable and accurate spectral chirps. Second, an evolutionary algorithm can be employed to reach specific temporal profiles. 相似文献
19.
An argon filled hollow fiber with metal coating on the inner glass surface has been used for nonlinear ellipse rotation of femtosecond optical pulses at 800 nm. Pulse contrast can be achieved using this waveguide with higher transmission compared with a fused silica waveguide. 相似文献
20.
Adaptive femtosecond pulse compression 总被引:2,自引:0,他引:2
A practical adaptive method for femtosecond optical pulse compression is demonstrated experimentally for the first time to our knowledge. The method is robust and capable of handling the general case of pulse compression, in which the input pulses are completely uncharacterized or partially characterized. 相似文献