非线性左手材料中的背向参量放大

Bidirectional parametric amplification in nonlinear left-handed metamaterials

基于电磁场理论,推导了非线性左手材料中的差频耦合波方程,以及相位匹配条件下介质内信号波与闲频波放大过程和场分布。发现有限厚度的非线性左手介质,可补偿损耗的影响,能够得到比右手介质更大的信号波和闲频波能量输出。提出非线性左手背向参量振荡器,在一定的泵浦条件下,不需要外加谐振腔也可以产生振荡。这为非线性左手材料在参量放大器中的应用奠定了理论基础。

Based on the electromagnetic theory, difference-frequency couple-mode equations of nonlinear left-handed metamaterials （LHM） are studied. Energy amplification process and spatial distribution of signal field and idler field under phasematching condition are investigated. It is shown that in a finite thickness metamate- rial slab, losses can be compensated by bidirectional parametric amplification, and more output power of signal wave and difference-frequency wave than a RHM slab with the same thickness can be obtained. Under some definite pump conditions, nonlinear LHM bidirectional parametric oscillator can generate oscillations without an outlaying cavity. This work provides a theoretical basis to the applications of nonlinear LHM in the parametric amplifiers.