Modulation instability in negative refractive metamaterials with exponential saturable nonlinearity and self-steepening effects |
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Authors: | Xianqiong Zhong Tingting Tang Anping Xiang Ke Cheng |
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Institution: | College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu, Sichuan 610225, China |
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Abstract: | Modulation instability (MI) in negative refractive metamaterials with exponential saturable nonlinearity and the self-steeping effect is investigated by using the standard linear stability analysis and the Drude electromagnetic model. The dispersion relation, instability condition, cut-off frequency, gain spectrum, and their corresponding dimensionless expressions are analytically deduced and then calculated. The results show that, the self-steepening effect will suppress MI by decreasing the cut-off frequency and the maximum gain. And the larger the power density ratio is, more slowly the cut-off frequency and the maximum gain decrease with increase of the self-steepening parameter. Although the sign of the self-steepening parameter does not influence MI but its absolute value must be smaller than a certain value. Depending on different self-steepening parameters, the cut-off frequency and maximum gain may decrease or increase before decrease with increase of the power density ratio. In particular, for large self-steepening parameters, the power density ratio may have a threshold value. When the power density ratio is under this threshold, MI will disappear. |
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Keywords: | Modulation instability Negative refractive metamaterials Exponential saturable nonlinearity Self-steepening effect |
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