Wang Xi, Ma Qian, Wu Leiming, Guo Jun, Lu Shunbin, Dai Xiaoyu, Xiang Yuanjiang
Opt Express. 2018 Mar 5;26(5):5488-5496. doi: 10.1364/OE.26.005488.
Black phosphorus (BP), a promising new two-dimensional (2D) material, has drawn a lot of attentions in academia and industry due to its extraordinary physical and chemical properties. In this paper, we theoretically demonstrate a monolayer BP that achieves coherent perfect absorption (CPA) at the THz/infrared band. It is found that quasi-CPA point does exist at the THz/infrared band. The CPA, which has a relative bandwidth of 141.3% and a coherent absorptivity of more than 90%, can be implemented at the quasi-CPA wavelength through a proper phase modulation. Moreover, the coherent absorptivity can be modulated with a high modulation depth by means of the phase difference between the two coherent counter-propagating beams. The angular selectivity of the monolayer BP is also investigated. The CPA wavelength is divided into two wavelength branches for TE and TM polarization at oblique incidence. In addition, the CPA wavelength can be tuned from THz to infrared band by adjusting the electron doping of the BP while maintaining the modulation depth of 10. Hence, our results may be potentially used for coherent modulations in terahertz/infrared detections and signal processing with 2D materials.
黑磷（BP）作为一种很有前景的新型二维（2D）材料，因其非凡的物理和化学性质而在学术界和工业界备受关注。在本文中，我们从理论上证明了一种单层BP在太赫兹/红外波段实现了相干完美吸收（CPA）。研究发现，在太赫兹/红外波段确实存在准CPA点。通过适当的相位调制，可在准CPA波长处实现相对带宽为141.3%且相干吸收率超过90%的CPA。此外，借助两束相干反向传播光束之间的相位差，相干吸收率可被高调制深度调制。还研究了单层BP的角度选择性。在斜入射时，CPA波长对于TE和TM偏振被分为两个波长分支。另外，在保持调制深度为10的同时，通过调整BP的电子掺杂，CPA波长可从太赫兹波段调谐到红外波段。因此，我们的结果可能潜在地用于太赫兹/红外检测中的相干调制以及二维材料的信号处理。
