Tunable terahertz coherent perfect absorption in a monolayer graphene
Tunable terahertz coherent perfect absorption in a monolayer graphene
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单层石墨烯中的可调谐太赫兹相干完美吸收
DOI：
10.1364/ol.39.006269
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发表时间：
2014-11-01
期刊：
影响因子：
3.6
通讯作者：
Li, Hongqiang
中科院分区：
文献类型：
--
作者：
Fan, Yuancheng;Zhang, Fuli;Li, Hongqiang
相干完全吸收体（CPA）被认为是激光的时间反演对应体：一个含有损耗介质而不是增益介质的谐振腔可以完全吸收相干光场。在这里，我们利用单层石墨烯以非共振方式实现CPA。研究发现，在悬浮单层石墨烯的太赫兹波段存在准CPA点，在准CPA频率下，通过两束入射光之间的适当相位调制，可以实现CPA.发现石墨烯基CPA具有宽带角选择性：CPA点在斜入射时对于正交的s和p偏振分裂为两个频带，并且这两个频带覆盖从零频率开始的宽频率范围。此外，相干吸收可以通过改变栅极控制的费米能量来基本上调谐。非共振石墨烯片CPA的研究结果可以推广到太赫兹/红外探测和二维光电材料的信号处理的潜在应用。(C)2014年美国光学学会
Coherent perfect absorber (CPA) was proposed as the time-reversed counterpart to laser: a resonator containing lossy medium instead of gain medium can absorb the coherent optical fields completely. Here, we exploit a monolayer graphene to realize the CPA in a nonresonant manner. It is found that quasi-CPA point exists in the terahertz regime for suspending monolayer graphene, and the CPA can be implemented with the assistance of proper phase modulation among two incident beams at the quasi-CPA frequencies. The graphene-based CPA is found of broadband angular selectivity: CPA point splits into two frequency bands for the orthogonal s and p polarizations at oblique incidence, and the two bands cover a wide frequency range starting from zero frequency. Furthermore, the coherent absorption can be tuned substantially by varying the gate-controlled Fermi energy. The findings of CPA with nonresonant graphene sheet can be generalized for potential applications in terahertz/infrared detections and signal processing with two-dimensional optoelectronic materials. (C) 2014 Optical Society of America