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61.
A. Fratalocchi K. A. Rutkowska M. A. Karpierz G. Assanto 《Opto-Electronics Review》2007,15(4):210-214
We investigate all-optical Zener tunnelling in electro-optically tunable arrays of identical channel waveguides in undoped
nematic liquid crystals. By all-optically inducing a refractive acceleration, we demonstrate a novel technique for band-to-band
tunnelling, as well as a novel approach to light controlled steering and readdressing. 相似文献
62.
Nonlocal spatial soliton interactions in nematic liquid crystals 总被引:17,自引:0,他引:17
The interaction between spatial optical solitons in undoped nematic liquid crystals is governed by reorientational nonlinearity with a significant nonlocality. We demonstrate several cases of interactions, including crossing, interlacing, and merging of spatial solitons in voltage-biased liquid-crystal cells. A scalar model accounts for the main features that were experimentally observed. 相似文献
63.
We investigate multiband optical breathers in a voltage-adjustable array of coupled waveguides in nematic liquid crystals. Symmetric breathers resulting from vector composition of modes from two bands are observed over large propagation distances and are described in terms of the Floquet-Bloch theory. 相似文献
64.
We propose and analyze a novel geometry for all-optical processing of low-power signals that is based on a frequency-nondegenerate counterpropagating parametric amplifier. The stationary response in the cascading regime exhibits multivalued solutions with enhanced nonlinear phase shifts. Implementation in a quasi-phase-matched LiNbO(3) waveguide is discussed. 相似文献
65.
We review the theory of light localization due to the combined action of single or double Bragg coupling between dichromatic counterpropagating envelopes and parametric mixing nonlinearities. We discuss existence, stability, and excitation of such localized envelopes. We also investigate the link between stationary gap solitons and input-output response of nonlinear quadratic Bragg gratings. Frustrated transmission and multistable switching is expected to occur under suitable integrable (cascading) limits. Substantial deviations from these conditions lead to the onset of spatial chaos. (c) 2000 American Institute of Physics. 相似文献
66.
We demonstrate two-dimensional spatial solitons excited by near-infrared picosecond pulses in Kerr-like heavy metal oxide glasses with a nonlinearity one order of magnitude larger than in fused silica. Solitons were obtained at 820 nm owing to the presence of multiphoton absorption, which prevented catastrophic collapse. 相似文献
67.
We investigate total internal reflection of optical spatial solitons at the interface between two regions of nematic liquid crystals with different optical densities. Due to nonlinear molecular reorientation, the solitons experience a penetration depth, hence, a lateral shift that depends on the excitation, with lateral shifts from 0.7 to 1.2 mm as input powers increased from 1.6 to 9.3 mW. 相似文献
68.
We investigate Landau-Zener tunneling in one-dimensional liquid crystalline waveguide arrays by all-optical impression of acceleration with an additional beam. We derive the Zener model from the governing equations and demonstrate a novel approach to Floquet-Bloch band tunneling. 相似文献
69.
By numerically integrating the three-dimensional Maxwell equations in the time domain with reference to a dispersive quadratically nonlinear material, we study second-harmonic generation in planar photonic crystal microresonators. The proposed scheme allows efficient coupling of the pump radiation to the defect resonant mode. The outcoupled generated second harmonic is maximized by impedance matching the photonic crystal cavity to the output waveguide. 相似文献
70.
We investigate the emission of solitons at a nonlinear longitudinal defect. We discuss the basic physics and introduce a novel approach to achieve complete nonlinear control of the process. Theoretical results are confirmed by numerical simulations. 相似文献