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arXiv 1706.06641physics.optics
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声子与等离子体的相对优点:能量平衡方法

Relative merits of Phononics vs. Plasmonics: the energy balance approach

Jacob B Khurgin

摘要:

各种等离子体激元方案的共同特征是它们能够将表面等离子体激元(SPP)的光场限制到亚波长体积中,从而实现线性和非线性光学性质的大幅增强。然而,即使是最好的金属,这种能力也受到固有的大欧姆损耗的严重限制。然而,在光谱的中红外和远红外范围内,存在一种可行的金属、极性氮化物和半导体的替代品,其中介电常数(实部)在Reststrahlen区域变为负值。这一特征产生了所谓的表面声子极化激元(SPhPs),它能够以类似于等离子体激元类似物SPPs的方式限制场。由于极性声子的阻尼率基本上小于自由电子的阻尼率,因此期望声子器件可以胜过它们的等离子体对应物并非不合理。然而,对声子和等离子体的比较优点的更严格的分析揭示了一个更微妙的答案,即虽然声子方案确实表现出更窄的共振并且可以实现非常高程度的能量集中,但是大部分能量以晶格振动的形式包含,使得电场的增强以及因此的Purcell因子,与金属纳米天线相比是相当小的。尽管如此,声子共振的绝对狭窄性预计将使声子在频率选择性很重要的应用中可行。

英文摘要:

The common feature of various plasmonic schemes is their ability to confine optical fields of surface plasmon polaritons (SPPs) into sub-wavelength volumes and thus achieve a large enhancement of linear and nonlinear optical properties. This ability, however, is severely limited by the large ohmic loss inherent to even the best of metals. However, in the mid and far infrared ranges of the spectrum there exists a viable alternative to metals, polar dielectrics and semiconductors in which dielectric permittivity (the real part) turns negative in the Reststrahlen region. This feature engenders the so-called surface phonon polaritons (SPhPs) capable of confining the field in a way akin to their plasmonic analogues, the SPPs. Since the damping rate of polar phonons is substantially less than that of free electrons, it is not unreasonable to expect that phononic devices may outperform their plasmonic counterparts. Yet a more rigorous analysis of the comparative merits of phononics and plasmonics reveals a more nuanced answer, namely that while phononic schemes do exhibit narrower resonances and can achieve a very high degree of energy concentration, most of the energy is contained in the form of lattice vibrations so that enhancement of the electric field, and hence the Purcell factor, is rather small compared to what can be achieved with metal nanoantennas. Still, the sheer narrowness of phononic resonances is expected to make phononics viable in applications where frequency selectivity is important.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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