共查询到20条相似文献,搜索用时 0 毫秒
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Cohen O Zhang X Lytle AL Popmintchev T Murnane MM Kapteyn HC 《Physical review letters》2007,99(5):053902
We propose a new technique for phase matching high harmonic generation that can be used for generating bright, tabletop, tunable, and coherent x-ray sources at keV photon energies. A weak quasi-cw counterpropagating field induces a sinusoidal modulation in the phase of the emitted harmonics that can be used for correcting the large plasma-induced phase mismatch. We develop an analytical model that describes this grating-assisted x-ray phase matching and predicts that very modest intensities (<10(10) W/cm2) of quasi-cw counterpropagating fields are required for implementation. 相似文献
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A 2D, square lattice, vectorial photonic crystal is formed by vectorial holography using an azo-dye-doped liquid-crystal material. Four coherent beams are interfered to generate a highly stable, switchable polarization holography structure. The formation of the vectorial lattice by the liquid-crystal molecular orientation is confirmed by diffraction pattern and polarization microscopy analysis. Simulations of the alignment and diffraction pattern are in good agreement with the experimental results. Polarization sensitive diffraction behavior is also consistent with the Kakichashvili model. 相似文献
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We analyze quasi-phase-matched (QPM) conversion efficiency of the five possible types of periodic two-dimensional nonlinear
structures: Hexagonal, square, rectangular, centered-rectangular, and oblique. The frequency conversion efficiency, as a function
of the two-dimensional quasi-phase-matching order, is determined for the general case. Furthermore, it is demonstrated for
two basic feasible motifs, a circular motif and a rectangular motif. This enables to determine the optimal motif dimensions
for achieving the highest conversion efficiency. We find that a rectangular motif is more efficient than a circular motif
for quasi-phase-matched processes that rely on a single reciprocal lattice vector (RLV), and that under optimal choice of
motif dimensions, it converges into a one-dimensional periodic structure. In addition, in a few specific cases we found that
higher order QPM can be significantly more efficient than lower order QPM. 相似文献
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H. Vogt 《Applied Physics A: Materials Science & Processing》1974,5(2):85-96
The paper is intended to illustrate that nonlinear optical phenomena yield useful information about structural phase transitions in crystals. Emphasis is placed on collinear second harmonic generation (SHG) and on second harmonic scattering (SHS). The temperature dependence of higher-rank tensors describing SHG is discussed in detail and is related to variations of long- and short-range order. Several kinds of SHS are considered and explained by modulations of the nonlinear optical susceptibility. Particular attention is paid to results obtainable by SHS, but not by ordinary scattering of light. 相似文献
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We present a general, analytical formula for the calculation of the unit vectors of the direction of vibration of the electric field strength in biaxial crystals. By means of this formula it is possible to calculate the effective nonlinearity for second-order nonlinear optical frequency conversion processes in biaxial crystals. For two highly efficient nonlinear optical crystals we have calculated the effective nonlinear susceptibility and walk-off angles. The results have been compared with numerical as well as experimental data of previous papers. 相似文献
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HMOinnonlinearopticsGUOHong;LINTao;WANGGang;DENGXiming(NationalLaboratoryonHighPowerAuserandPhysics,ShanghaiInstituteofOptics... 相似文献
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M. Sylla D. Rou de R. Chevalier X. Nguyen Phu G. Rivoire 《Optics Communications》1992,90(4-6):391-398
We have observed a very strong nonlinear absorption in BSO and BGO crystals when they are illuminated by picosecond laser pulses with optical intensity on the order of 108 W/cm2. In addition, a phase conjugate reflectivity of 2×10-3 is obtained in a degenerate four-wave mixing (DFWM) experiment using the same optical power. We derive the nonlinear coupled-wave equations to explain the experimental results. We show that the creation of the conjugate wave can be explained by the presence of a strong nonlinear absorption. 相似文献
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New efficient mechanisms of long-wavelength excitation of short-wavelength luminescence in a system of rare-earth impurity ions are proposed. The model studied involves a multilevel system of electronic states of a rare-earth ion interacting with the long-wavelength emission that is in resonance with one or several transitions between the excited levels. The concentration of impurity ions is assumed to be sufficiently high, so that the interionic cross-relaxation and the up-conversion play a significant role. Moreover, the model includes processes similar to photon avalanche, in which the photoinduced excitation of a single ion is converted into lower-level excitations of several ions, each of them reentering the process after photon absorption. Numerical solutions of the system of balance equations for a multilevel system are obtained with calculated and semiempirical parameters of self-quenching and up-conversion. It is shown that, in a system of Tm3+ impurity ions, short-wavelength luminescence at λ≥0.29 μm can be efficiently excited by radiation at λ?1.11 or 0.649 μm with a moderate intensity. 相似文献
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S. G. Rautian 《Optics and Spectroscopy》2008,104(1):112-120
A one-dimensional harmonic model of a photonic crystal is considered using the methods of physical optics. The theoretical formalism is based on the notion of the Fresnel volume reflection and the system of two first-order differential equations, which are equivalent to the wave equation. Using the Rayleigh layer as an example, it is shown that the volume reflection plays a role of the friction, similar to the friction in oscillations of a pendulum, and, in a strongly inhomogeneous medium, can suppress field oscillations and turn the group velocity to zero. In the approximation of small modulation factor, the models of two, four, and six waves are considered. In the two-wave model, the dispersion relation contains a zone of inhomogeneous waves, whose width is determined by the Fresnel reflection coefficient from one period. The refinement in terms of the four-wave or six-wave model yields only a small correction to the position of the zone, retaining its width unchanged. The wavenumber as a function of frequency is described by a circle inside the zone of inhomogeneous waves and by a hyperbola outside this zone. Mathematically, the method used is significantly simpler than those based on the application of the Floquet theorem to the wave equation. It is shown that the notion of forbidden zones is inconsistent with respect to photonic crystals, and the term zones of inhomogeneous waves is proposed instead. 相似文献
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A few models of nonlinear optical systems, known experimentally to possess both stable and unstable dynamical modes, are approximated by different dynamical models and integrated by different numerical methods. It is shown that the onset of instabilities and chaotic behavior in the same physical system may be dependent on the model used and on the numerical method applied. Finite order difference schemes should be applied with caution to infinite dimensional dynamical systems displaying irregular behavior. 相似文献
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Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable-coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota’s bilinear method. The bilinear forms and analytic soliton solutions are derived, and the relevant properties and features of oscillating solitons are illustrated. Oscillating solitons are controlled by the reciprocal of the group velocity and Kerr nonlinearity. Results of this paper will be valuable to the study of dispersion-managed optical communication system and mode-locked fibre lasers. 相似文献
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H. Haken 《Optical and Quantum Electronics》1970,2(3):161-167
We consider nonlinear optical devices which are excited by coherent light from a laser and in which several other waves are generated by nonlinear processes. We develop a general theory to treat the noise properties of the generated waves. In particular a probability distribution function is found which in principle can be measured experimentally. This formulation allows a thermodynamic study of phase transitions. 相似文献
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R. Stolle G. Marowsky E. Schwarzberg G. Berkovic 《Applied physics. B, Lasers and optics》1996,63(5):491-498
Measurement of the phase, and not only the intensity, of the nonlinear optical response of a system is important in many applications which are reviewed here. We demonstrate and compare several techniques for direct measurement of the phase of the nonlinear susceptibilities through nonlinear interferometry. Different ways of imparting a controllable phase shift are discussed. Unless the coherence length is impractically large, the preferred method is to use a variable-pressure gas cell to control the phase difference between the input laser pulse and the nonlinear optical signal.Prof. F. P. Schäfer on the occasion of his 65th birthday. 相似文献
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F. T. Arecchi G. Giusfredi E. Petriella P. Salieri E. Giacobino S. Cribier G. Grynberg F. Biraben H. M. Gibbs J. L. Jewell J. V. Moloney M. C. Rushford K. Tai S. S. Tarng D. A. Weinberger A. C. Gossard S. L. McCall A. Passner W. Wiegmann P. Martinot A. Koster S. Laval W. Carvalho A. Miller J. R. Hill G. Parry R. R. Puri R. K. Bullough S. S. Hassan A. M. Scott C. K. Wu P. Agostini G. Petite F. Fabre 《Applied physics. B, Lasers and optics》1982,29(3):169-175
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《Photonics and Nanostructures》2009,7(1):56-62
Quantum dots in photonic crystals are interesting both as a testbed for fundamental cavity quantum electrodynamics (QED) experiments and as a platform for quantum and classical information processing. We describe a technique to coherently access the QD-cavity system by resonant light scattering. Among other things, the coherent access enables a giant optical nonlinearity associated with the saturation of a single quantum dot strongly coupled to a photonic crystal cavity. We explore this nonlinearity to implement controlled phase and amplitude modulation between two modes of light at the single photon level—a nonlinearity observed so far only in atomic physics systems. We also measured the photon statistics of the reflected beam at various detunings with the QD/cavity system. These measurements reveal effects such as photon blockade and photon-induced tunneling, for the first time in solid state. These demonstrations lie at the core of a number of proposals for quantum information processing, and could also be employed to build novel devices, such as optical switches controlled at the single photon level. 相似文献