Achromatic on-chip focusing of graphene plasmons for spatial inversions of broadband digital optical signals  

作　　者：Zhiyong Wu Zhengji Xu 

机构地区：[1]Sun Yat-sen University,School of Microelectronics Science and Technology,Zhuhai,China [2]Sun Yat-sen University,Guangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems,Zhuhai,China

出　　处：《Advanced Photonics Nexus》2023年第5期56-63,共8页先进光子学通讯（英文）

基　　金：supported in part by the National Natural Science Foundation of China(Grant No.62105376);the Guangdong Zhujiang Project(Grant Nos.2021ZT09X070 and 2021QN02X488).The authors declare no competing financial interests。

摘　　要：On-chip focusing of plasmons in graded-index lenses is important for imaging,lithography,signal processing,and optical interconnects at the deep subwavelength nanoscale.However,owing to the inherent strong wavelength dispersion of plasmonic materials,the on-chip focusing of plasmons suffers from severe chromatic aberrations.With the well-established planar dielectric grating,a graded-index waveguide array lens(GIWAL)is proposed to support the excitation and propagation of acoustic graphene plasmon polaritons(AGPPs)and to achieve the achromatic on-chip focusing of the AGPPs with a focus as small as about 2%of the operating wavelength in the frequency band from 10 to 20 THz,benefiting from the wavelength-independent index profile of the GIWAL.An analytical theory is provided to understand the on-chip focusing of the AGPPs and other beam evolution behaviors,such as self-focusing,self-collimation,and pendulum effects of Gaussian beams as well as spatial inversions of digital optical signals.Furthermore,the possibility of the GIWAL to invert spatially broadband digital optical signals is demonstrated,indicating the potential value of the GIWAL in broadband digital communication and signal processing.

关 键 词：achromatic lens self-focusing lens graded-index lens waveguide array broadband focusing graphene plasmon 

分 类 号：TN2[电子电信—物理电子学]