| Zhong Xian-qiong.Modulation instability in negative refractive materials with saturable nonlinearity[J].Optoelectronics Letters,2012,8(2):157-160 |
| Modulation instability in negative refractive materials with saturable nonlinearity |
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| Abstract: |
| Starting directly from the nonlinear propagation equation including saturable nonlinearity, the first- and the second-order
nonlinear dispersions, the dispersion relation, instable condition, gain spectra, and the dimensionless cut-off frequency
and gain spectra of modulation instability (MI) in the negative refractive material are deduced by adopting the linear stability
analysis and Drude electromagnetic model. And the variations of the dimensionless gain spectra with the normalized angular
frequency and normalized incident power are calculated and discussed for different sign relations between the linear dispersion
and the third-order nonlinear coefficients. The results show that in the negative refractive index region, MI can occur irrespective
of the sign relation between the linear dispersion and the third-order nonlinear coefficients. And depending on different
dimensionless angular frequencies and different sign relations, the variations of the dimensionless gain spectra with incident
power take on several different forms. Namely, the peak gain and the cut-off frequency of MI may increase then decrease with
the increase of the incident power, or decrease monotonously. Moreover, MI may even have a threshold incident power for some
cases. |
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| This work has been supported by the Key Project of Chinese Ministry of Education (No. 210186), and the Scientific Research Foundation of CUIT
(No.2010d1). |
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