频率对二维声子晶体平板负折射成像的影响  

Effect of frequency on negative refraction imaging in two-dimensional phononic crystal slab

作　　者：刘绍娥[1] 贺萌[1] 覃世冬[1] 李晓春[1,2] 周科朝[2] 黄伯云[2] 

机构地区：[1]中南大学物理科学与技术学院,湖南长沙410083 [2]中南大学粉末冶金研究院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2011年第9期2658-2662,共5页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(10674181);中南大学博士后科学基金资助项目(2008年)

摘　　要：以二维钢/空气三角排列声子晶体为模型,利用多重散射方法分析声子晶体平板负折射成像过程中声波频率与等效负折射率、入射角的变化关系。研究结果表明:平板负折射成像与声波频率及波的入射角度密切相关;对不同的入射波频率,平板的等效负折射率不同,且随着频率增加,等效负折射率绝对值变小;对于确定的晶格结构,只有在确定的频率范围、确定的入射角范围内,才能发生明显的负折射现象;对于某一确定的入射波频率,平板负折射存在一个最大入射角,且随着入射声源频率的增加,这个最大入射角变小,入射波耦合进入声子晶体平板的信号减弱,进而影响像的强度和清晰度。By multiple-scattering method,phononic crystals consisting of steel cylinders hexagonal arrayed in air were taken as examples to illuminate the relationship between the effective negative refractive index and frequency of sound waves,as well as incident angle,in two-dimensional phononic crystal slabs.The results show that the frequency and incident angle of sound waves have close effect on the negative refractive imaging in two-dimensional phononic crystals slabs.For different sound wave frequencies,there is different effective negative refractive index,and with the increase of sound wave frequency in which the negative refraction imaging exists,the absolute modulus of the effective negative refractive index decreases.For a certain phononic crystal structure,negative refraction images can only be obtained in a certain frequency range and a special incident angles range.For a given frequency of sound wave,there exists a maximum incident angle to negative refracting.With the increase of frequency of sound wave,the maximum incident angle decreases,and furthermore,the image intensity reduces,and the image becomes blurry.

关 键 词：声子晶体 负折射 等效负折射率 频率 入射角 

分 类 号：O422.3[理学—声学]