Plasmonics in graphene at infrared frequencies
Plasmonics in graphene at infrared frequencies
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DOI：
10.1103/physrevb.80.245435
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发表时间：
2009-12-01
影响因子：
3.7
通讯作者：
Soljacic, Marin
中科院分区：
文献类型：
--
作者：
Jablan, Marinko;Buljan, Hrvoje;Soljacic, Marin
我们指出，在掺杂石墨烯的等离子体激元同时使低损耗和显着的波定位的频率低于光学声子分支h Ω（OPH）近似为0.2 eV。大的等离子体激元损失发生在带间区域（通过电子-空穴对的激发），其可以被推向更高的频率以获得更高的掺杂值。对于足够大的掺杂，有一个带宽的频率从ω（Oph）到带间阈值，其中通过发射的光学声子与电子空穴对的等离子体激元衰减通道是nonegligable。损失的计算是在随机相位近似和守恒松弛时间近似的框架内进行的。测得的DC弛豫时间作为输入参数表征与杂质的碰撞，而从光学声子的贡献估计的电子-声子耦合的光学电导率的影响。石墨烯中等离子体激元的光学性质在许多相关方面类似于在电介质-金属界面上传播的表面等离子体激元的光学性质，由于其在纳米光子学中的重要性，最近引起了很多兴趣。因此，石墨烯中的等离子体激元对于某些频率可能具有低损耗的事实使得它们对于纳米光子应用具有潜在的兴趣。
We point out that plasmons in doped graphene simultaneously enable low losses and significant wave localization for frequencies below that of the optical phonon branch h omega(Oph)approximate to 0.2 eV. Large plasmon losses occur in the interband regime (via excitation of electron-hole pairs), which can be pushed toward higher frequencies for higher-doping values. For sufficiently large dopings, there is a bandwidth of frequencies from omega(Oph) up to the interband threshold, where a plasmon decay channel via emission of an optical phonon together with an electron-hole pair is nonegligible. The calculation of losses is performed within the framework of a random-phase approximation and number conserving relaxation-time approximation. The measured DC relaxation-time serves as an input parameter characterizing collisions with impurities, whereas the contribution from optical phonons is estimated from the influence of the electron-phonon coupling on the optical conductivity. Optical properties of plasmons in graphene are in many relevant aspects similar to optical properties of surface plasmons propagating on dielectric-metal interface, which have been drawing a lot of interest lately because of their importance for nanophotonics. Therefore, the fact that plasmons in graphene could have low losses for certain frequencies makes them potentially interesting for nanophotonic applications.