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Large Bandwidth Optical Limiting by Kerr Medium Doped One-Dimensional Coupled Cavity Optical Waveguides 总被引:2,自引:0,他引:2
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We present a new method to realize large bandwidth optical limiting using Kerr nonlinearity doped one-dimensional coupled cavity optical waveguides (CCOWs). When the incident intensity is weak, the structure is a perfect CCOW that supports a high transmission band. When the intensity is increased, the Kerr effects change the refractive index of the Kerr cavity which results in a large decrease of transmission coefficients in the whole band. We numerically analyse the limiter using the nonlinear transfer matrix method and nonlinear finite difference in time domain method. Optical limiting effects are observed in the whole transmission band, and optimization methods are also discussed. 相似文献
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Enhancement of Available Conversion Efficiency of Optical Parametric Amplifier in a Cascaded Photonic Crystal Structure
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Using the cascaded structure of a linear and a second-order nonlinear photonic crystals, we realize a high-efficiency optical parametric amplifier in the case of exact phase matching. This proposal is verified using the slow-envelope nonlinear finite difference time domain numerical method. Compared with the case of the individual nonlinear photonic crystal structure, the oscillation threshold is decreased obviously; and the peak power amplification factor of the transmitted signal is enhanced more than 20 times. 相似文献
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We numerically investigate the localization behaviour of light propagation in a one-dimensional nonlinear photonic crystal (1D-NPC). It is found that the localization of a high gap-edge mode is better than that of a low one, so that the switching threshold of the 1D-NPC with plus Kerr L-layers is much lower than that with minus Kerr H-layers. For a structure of 16 periods, the threshold of the structure with nonlinear L-layers is about 1/10 of that with nonlinear H-layers in the same level of nonlinear refractive coefficient. 相似文献
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A new mechanism of intersection formed by two line defect photonic crystal (PC) waveguides are numerically investigated using the finite-diFference time-domain method. The results show that the normalized crosstalk is smaller than 10^-4; the reflection is smaller than 10^-3, and the transmission is larger than 0.999. The authors analyse the physical origins and find that a modified self-imaging process in the intersected multi-mode region is the main reason of the excellent performance. This kind of multi-mode interference based intersection may find potential applications in PC optical circuits. 相似文献
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二维光子晶体耦合腔的多模双稳态光开关 总被引:2,自引:1,他引:1
利用时域有限差分数值模拟方法和耦合模理论分析方法,研究了Kerr型非线性二维光子晶体耦合腔结构中的光学双稳态开关。利用耦合模理论,分析了耦合腔结构的多模特性,以及对应本征态的局域强度分布特性,并讨论了在耦合腔结构中实现多模光学双稳态开关的原理。发现在二维耦合腔结构中,可以实现信号自泵浦和泵浦-信号两种类型的双稳态开关,且后者具有使泵浦和信号在频率和空间相分离的优点。利用非线性时域有限差分数值模拟方法,得到了高斯脉冲激励下的双稳态响应曲线。 相似文献
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Broadband Frequency Down-Conversion Using Coupled Cavity Structures in One-Dimensional Photonic Crystals
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The frequency down-conversion of one-dimensional photonic crystals with the coupled cavity structure is investigated by the nonlinear finite-difference time-domain method. The efficient frequency conversion is obtained by utilizing the advantages of the broad eigenfrequency band, the strong localization and the Bloch phase matching of the coupled cavity structure. More importantly, the signal frequency could be tuned continuously within the whole band of the coupled cavity structure (with a bandwidth to central frequency ratio of 5.4%), and the gains are homogeneous in the band. 相似文献
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An Optical Parametric Amplifier in Photonic Crystals of Nondispersive Medium with Perfect Bloch Phase Matching
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One-dimensional photonic crystal of second-order nonlinearity is studied. Among the three waves of the parametric interaction process of down-conversion with a nondispersive medium, two gap-edge localized modes and one travelling-mode are proposed, and an exact phase matching condition is realized using the periodic condition 相似文献
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Transmission properties of photonic crystal (PC) waveguides with discretely modulated exit surfaces are investigated numerically using the finite-difference time-domain (FDTD) method. Unlike the case of periodically modulated surfaces, where the transmission beam tends to be a single and directional beam, when the exit surfaces are modulated only at several discrete points, the emission power tends to split into multiple and directional beams. We explain this phenomenon using a multiple point source interference model. Based on these results, we propose a 1-to-N beam splitter, and numerically realized high efficiency coupling between a PC sub-wavelength waveguide and three traditional dielectric waveguides with a total efficiency larger than 92%. This simple, easy fabrication, and controllable mechanism may find more potential applications in integrated optical circuits. 相似文献
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The coupling of a stub obliquely intersected with a metal-dielectric-metal plasmonic waveguide is investigated by using the finite difference in time domain method. Results show that an odd mode, except for the usual even mode, is excited in the stub due to the symmetry breaking of the oblique intersection. Moreover, the results show that tile quality factor of the odd mode is very high in comparison with that of the usual even mode, which is then explained by the symmetry breaking of the oblique stub intersection. The superposition of the even and the odd mode generates a Fano shaped spectrum with a very narrow linewidth. The effect of metallic loss and compensation are also discussed. Both the stub and the waveguide are compact in size, and simple in structure, which are beneficial for the achievements of narrow band filtering, sensing, lasing, and nonlinearity enhancement. 相似文献
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