基于石墨烯双曲色散腔中回音廊共振的纳米激光器  

Nanolasers based on whispering-gallery resonances in graphene cavities with hyperbolic dispersion

作　　者：李艳[1] 钟发成 褚博 邵立[1] 王俊俏[2] 万明杰 杨鹏 王妍妍 丁佩[1] 曾凡光[1] 于占军 许坤[1] 杜银霄[1] 霍海波[1] 陈卓[4] 王振林[4] LI Yan;ZHONG Fa-Cheng;CHU Bo;SHAO Li;WANG Jun-Qiao;WAN Ming-Jie;YANG Peng;WANG Yan-Yan;DING Pei;ZENG Fan-Guang;YU Zhan-Jun;XU Kun;DU Yin-Xiao;HUO Hai-Bo;CHEN Zhuo;WANG Zhen-Lin(School of Materials Science and Engineering,Zhengzhou University of Aeronautics,Zhengzhou 450046,China;School of Physics,Zhengzhou University,Zhengzhou 450052,China;College of Optical and Electronic Technology,China Jiliang University,Hangzhou 310018,China;School of Physics,Nanjing University,Nanjing 210093,China)

机构地区：[1]郑州航空工业管理学院材料学院,郑州450046 [2]郑州大学物理学院,郑州450052 [3]中国计量大学光学与电子科技学院,杭州310018 [4]南京大学物理学院,南京210093

出　　处：《中国科学：物理学、力学、天文学》2021年第10期118-129,共12页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:11704344,11904344,11847099,11947089,61704156);河南省科技攻关项目(编号:202102210052,182102210451,192102210002);航空科学基金(编号:2019ZF055002,2017ZC55006);河南省自然科学基金(编号:212300410414)资助项目。

摘　　要：本文设计并研究了基于石墨烯球形双曲色散超材料腔(由多层石墨烯和介质交替包裹介质核组成)中回音廊共振的纳米激光器.首先说明该石墨烯-介质核壳结构具有双曲型色散关系,支持共振波长远大于腔尺寸的回音廊模式,能够把电场局域在深度亚波长的区域.另外,由于该腔支持多个不同阶次的偶极回音廊共振,并能够在不同介质层中形成强约束电场,具有高Purcell因子.因此,通过在相应的介质层引入增益,可实现多波长激射,且阈值较低.对于直径404 nm的腔,在32.3μm的激射阈值仅为80.6 cm-1.进一步说明通过改变介质折射率、石墨烯费米能级或石墨烯/介质层对数,还能够实现激射波长的宽带调谐.最后说明对于仅由2对石墨烯/介质层组成的回音廊共振腔,最大共振波长和直径比也达到约50倍,相应的激射阈值仅90.74 cm-1.该纳米激光器兼备了深度亚波长、低阈值和宽带可调谐等特性,有望在太赫兹集成器件中发挥重要的应用.We theoretically propose a novel nanolaser based on whispering-gallery resonances(WGRs)in spherical cavities with hyperbolic dispersion,composed of a dielectric core alternately wrapped by graphene and dielectric layers.First,we showed that the multilayer graphene-dielectric core-shell cavities have a negative dielectric constant in at least one direction and exhibit an unusual hyperbolic dispersion.Such cavities can support the whispering-gallery modes with resonance wavelengths much larger than the cavity sizes and can strongly confine the electromagnetic fields in deep subwavelength regions.Moreover,multiple dipole WGR modes with different orders can be excited by such cavities,accompanied by high Purcell factors and strong confinement electric fields within different dielectric layers.Therefore,by introducing gain into these different dielectric layers,lasing at different resonance wavelengths can be realized with a low lasing threshold.For the cavity with a diameter of 404 nm,the lasing threshold at a wavelength of 32.3μm is only80.6 cm-1.Furthermore,we demonstrated that by manipulating the refractive index of the dielectric layers,graphene Fermi energy,or the number of pairs of graphene and dielectric layers,the lasing wavelengths in a wide spectral range could be easily adjusted.Finally,even for the relatively simple core-shell cavity with only two pairs of graphene and dielectric layers,the ratio of resonant wavelength and cavity diameter for the TM1,1 mode is approximately 50,and the lasing threshold is only 90.74 cm-1.This type of nanolasers has the characteristics of deep subwavelength,low threshold,and wide-band tunability.Hence,these lasers have great potential for applications in integrated terahertz devices.

关 键 词：MIE散射 石墨烯双曲色散腔 回音廊共振 纳米激光器 

分 类 号：TN248[电子电信—物理电子学]