硅基级联光栅石墨烯吸波器设计与分析  

Design and Analysis of a Graphene Absorber Using Silicon-Based Cascaded Gratings

作　　者：王睿 桑田 周健宇 李俊浪 

机构地区：[1]江南大学理学院光电信息科学与工程系,江苏无锡214122 [2]江南大学江苏省轻工光电工程技术研究中心,江苏无锡214122

出　　处：《微纳电子技术》2018年第3期154-160,共7页Micronanoelectronic Technology

基　　金：国家自然科学基金资助项目(61178032);中央高校自主科研基金资助项目(JUSRP115A15);江苏省轻工光电工程技术研究中心基金资助项目(BM2014402)

摘　　要：提出硅基级联光栅石墨烯吸波器设计,该吸波器由波导层光栅和缓冲层光栅上下级联而成,采用小角度入射,利用波导模式耦合形成的非简并波导模共振实现石墨烯条光吸收效率的显著增强。计算表明,2°入射硅波导光栅中非简并波导模为分裂的波导模式,其归一化光强的最大值较正入射情形增大了428倍;石墨烯条的峰值光吸收效率最高达83.3%,相对单层石墨烯的本征光吸收效率增大了36倍。研究发现吸收峰位置几乎不受缓冲层光栅深度变化影响,而吸收效率和透射率将随缓冲层光栅深度变化分别作趋势相反的类法布里-珀罗（Fabry-Pérot,FP）周期波动。此外,吸波器具有稳定的高吸收效率和较高的Q因子,改变波导光栅的深度和宽度,均可在光通信C波段实现吸收波长和Q因子的准线性调谐。A design of a graphene absorber using the silicon-based cascaded grating was presented.The graphene absorber is consisted of a waveguide grating at the top and a buffer grating at the bottom.With a small incident angle,the absorption of the graphene strips was significantly enhanced by using the resonance of the nondegenerate waveguide mode resulting from the coupling of the waveguide modes. The theoretical simulation shows that the nondegenerate waveguide mode in the silicon waveguide grating is the split waveguide mode at the incident angle of 2°,and the maximum normalized light intensity is enhanced 428 times comparing with that of the normal incidence.The maximum of the peak light absorption efficiency of the graphene strips is 83.3%,which is 36 times higher than the intrinsic light absorption efficiency of the monolayer graphene.The study shows that the location of the absorption peak is almost unaffected by the grating depth variation of the buffer layer,while the absorptivity and transmissivity fluctuate periodically in the opposite tendency like the Fabry-Pérot（FP）resonance with the variation of the buffer layer grating depth.In addition,the high absorption efficiency and high Qfactor of the absorber can be maintained,the quasi-linear tunings of the absorption wavelength and Qfactor is realized in the optical communication C-band by changing the depth and width of the waveguide grating.

关 键 词：石墨烯 硅基级联光栅 吸波器 非简并波导模 增强吸收 

分 类 号：TN304.18[电子电信—物理电子学] O59[理学—应用物理]