摘要
太赫兹(THz)技术因其在高速无线通信、无损成像、光谱检测等领域的应用价值而备受关注,然而能高效调制太赫兹波的材料仍亟需开发。由周期性亚波长结构组成的超材料可精确地调控电磁波的振幅、相位和偏振,为设计超紧凑和高性能太赫兹器件提供了新的机遇。太赫兹超材料可通过改变谐振模态进而调控太赫兹波,但米氏共振等常用模态由于较低的谐振强度导致调控效率有限。Fano谐振具有更强的谐振强度,且对外界介电环境十分敏感,可极大提高太赫兹波的调控效率和灵敏度。基于泵浦光激发高阻硅中非平衡载流子的机制,设计并实验验证了一种高效光调控的全介质太赫兹Fano超材料。结果表明:通过近红外激光泵浦控制高阻硅的电导率,可以实现Fano谐振强度的有效调控,调制率可达到87%,比同一结构上Mie式电偶极谐振的调制效率提高了70%,实现了对太赫兹波的高效调控。制备方法简单、调制效果明显,可通过改变超材料样品尺寸灵活设计工作频段,为太赫兹波段的高性能调控器件提供了一种可行的设计思路和方法。
Terahertz(THz)technology has attracted much attention due to its application potentials in high speed wireless communication,non-destructive imaging,spectroscopy and others.However,the development of the materials for THz modulation is still a challenge.Metamaterials composed of periodic subwavelength structures can precisely modulate the amplitude,phase and polarization of electromagnetic waves,providing some opportunities for designing ultra-compact and high-performance THz devices.THz metamaterials modulate THz based on its resonant behavior.However,the modulation efficiency of Mie resonance and other common resonances is not evident due to the low resonant strength.Fano resonance possesses a more intense resonant strength and is sensitive to external dielectric environment,thus greatly improving the efficiency and sensitivity of THz wave modulation.The optically-modulated all-dielectric THz Fano metamaterial with a high efficiency was proposed based on the mechanism of photogenerated non-equilibrium carriers in a high purity silicon.The results show that the optical pump of near infrared laser effectively modulates the Fano resonant strength via controlling the conductivity of high resistance silicon,and the modulation depth reaches 87%,which is 70%greater than that of Mie electric dipole resonance in the same structure,realizing the efficient modulation of terahertz wave.The preparation method is simple and the modulation effect is obvious.The resonant frequency of Fano metamaterial can be conveniently designed by varying the geometric size of the metamaterial,which provides a possible approach for the high-performance modulation devices in the THz regime.
作者
于凯新
赵世强
王陈
孙竞博
文永正
周济
YU Kaixin;ZHAO Shiqiang;WANG Chen;SUN Jingbo;WEN Yongzheng;ZHOU Ji(State Key Laboratory of New Ceramics and Fine Processing,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2023年第4期833-841,共9页
Journal of The Chinese Ceramic Society
基金
国家重点研发计划(2022YFB3806000)
国家自然科学基金基础科学中心(51788104)
国家自然科学基金(92163129,52072203)。
关键词
太赫兹
光调控
全介质
Fano超材料
terahertz
optical modulation
all-dielectric
Fano metamaterials
