基于光子晶体缺陷模频移的超快光控太赫兹波调制器  

Ultra-fast optical terahertz modulator based on defect mode frequency shift of photonic crystals

作　　者：高文杰 许艳霞 曾俊冬 黄仁杰 朱武 李高芳 GAO Wenjie;XU Yanxia;ZENG Jundong;HUANG Renjie;ZHU Wu;LI Gaofang(School of Electronic&Information Engin eering,Shanghai University of Electric Power,Shanghai 200082,China)

机构地区：[1]上海电力大学电子与信息工程学院,上海200082

出　　处：《光电子．激光》2023年第3期225-231,共7页Journal of Optoelectronics·Laser

基　　金：上海市自然科学基金(17ZR1411500);国网上海电力公司科技创新项目(H2020-073)资助项目。

摘　　要：本文设计了一种基于非线性光子晶体缺陷模频移实现太赫兹(terahertz,THz)波传输阻断的超快光控调制器,该调制器采用在硅基空气柱光子晶体中引入线缺陷和填充砷化镓材料的点缺陷结构,线缺陷形成波导区,传输频率位于光子带隙范围内的THz波,点缺陷作为谐振腔对THz波选频,与谐振频率(缺陷模频率)相同的THz波在谐振腔中发生谐振,耦合到波导中输出。无光激发时,位于线缺陷光子带隙内的1.65THz缺陷模频率在谐振腔中发生谐振,从波导的另一端输出,调制器处于“通”状态。当中心波长为810nm、光密度为0.4μJ/cm^(2)的抽运光激发时,砷化镓的折射率由3.55变为3.55-i2.55,使缺陷模频移,在亚纳秒超快时间内实现对1.65THz入射波的传输阻断。结果表明,该调制器的调制速率为2.3GHz,消光比为20.3dB,插入损耗为0.18dB,具有调制速率高、消光比大、插入损耗小等优点,为其在高速THz波通信系统中的应用提供重要的理论依据。A ultra-fast light-controlled modulator is designed for blocking terahertz(THz)wave propagation based on defect mode frequency shift of nonlinear photonic crystals.The modulator adopts the structure of introducing line defects and point defects filled with gallium arsenide materials in silicon-based air column photonic crystals.Due to the photonic band gap effect,waveguide region is formed at the line defect.THz waves with transmission frequencies within the photonic band gap can be transmitted in the waveguide.The point defect acts as a resonant cavity to select the frequency of THz waves,and the THz waves with the same resonant frequency(defect mode frequency)resonate in the resonant cavity and are coupled to the waveguide for output.When there is no light excitation,the 1.65THz defect mode frequency located in the photonic band gap of the line defect resonates in the resonant cavity and output from the other end of the waveguide,and the modulator is in the“on”state.On the other hand,the defect mode frequency shifts due to the refractive index of gallium arsenide filled point defect changes from 3.55to 3.55-i2.55with the excitation of the central wavelength 810nm and the optical density 0.4μJ/cm^(2).And the transmission of 1.65THz incident wave is blocked with the ultra-fast time of sub seconds.The results show that the modulator with modulation rate of 2.3GHz,extinction ratio of 20.3 dB,and insertion loss of 0.18dB has the advantages of high modulation rate,large extinction ratio and small insertion loss,which provides an important theoretical basis for its application in high-speed THz wave communication system.

关 键 词：光控调制器 THZ波 光子晶体 砷化镓 缺陷模频移 

分 类 号：O43[机械工程—光学工程]