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研究含负折射介质的不对称反向定向耦合器中的时空调制不稳定性(MI),探讨了输入功率、前向波和后向波功率比和通道间的耦合系数等对时空MI的影响。结果表明:在这种新型耦合器中只有当横向波数超过一定阈值时才会产生MI,增加输入功率或减少前向波和后向波的功率比都会扩大MI增益谱的范围并最终使MI区域重合,而降低耦合器通道间的耦合系数可减少MI的增益峰值但拓宽增益谱的范围。负折射介质的电磁参数可调谐特性为实现MI的主动调控和孤子的形成提供了新的方法和手段。
The space-time modulation instability (MI) in asymmetric reverse directional couplers with negative refraction medium is studied. The effects of input power, power ratio of forward and backward waves and the coupling coefficient between channels on space-time MI are discussed . The results show that in this new type of coupler, MI is generated only when the transverse wave number exceeds a certain threshold. Increasing the input power or decreasing the power ratio of the forward wave and the backward wave enlarges the range of the MI gain spectrum and finally makes the MI region Coincidence, while reducing the coupling coefficient between the coupler channels can reduce the MI gain peak but broaden the range of the gain spectrum. The tunability of the electromagnetic parameters of negatively-refracted media provides a new method and means for the active control of MI and the formation of solitons.