分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yifei Zhang
Baoqing Zhang
Mingming Feng
Haotian Ling
Xijian Zhang
Yiming Wang
Xiaomu Wang
Qingpu Wang
Aimin Song
摘要： Extraordinary optical transmission (EOT) is a phenomenon of exceptional light transmission through a metallic film with hole arrays enhanced by surface plasmon (SP) resonance, which stimulates renewed research hotspots in metamaterials, subwavelength optics, and plasmonics. Below the frequency of the first order SP mode, f_pl0, the metallic film typically shows strong reflection and no EOT. Here, we report an unusual EOT phenomenon below fpl0, i.e., beyond the long-held spectral boundary of classic EOTs. It is induced by a novel bound surface state in a Fabry-Perot(F-P) cavity comprising a holey gold film and a silicon-air interface. By tailoring the cavity length, EOT phenomenon has been pushed deep into the sub-wavelength region by a factor of as large as 20%, and EOT frequency comb with cavity function has been achieved. Due to the enhanced slow-wave effect as the frequency approaches fpl0, the cavity induced EOT gradually merges with the first order SP EOT. Distinguishing from the classic EOT phenomenon, no transmission zero is found between these two EOTs, which dramatically broadens the EOT bandwidth by a factor of 10 at terahertz (THz) frequencies. Furthermore, the EOT transmittance is actively modulated with graphene, achieving a large modulation range from 0.5 to 0.25 under a sub-volt bias from -0.3 to 0.5 V at 500 GHz. To the best of the authors' knowledge, both the modulation range and the low bias are among the best for active EOT devices with graphene to date. Such a structure provides a new strategy for miniaturizing sensing devices, high-power sources, and broadband photonics as well as their active control in the THz regime.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Mingming Feng
Baoqing Zhang
Haotian Ling
Zihao Zhang
Yiming Wang
Yilin Wang
Xijian Zhang
Pingrang Hua
Qingpu Wang
Aimin Song
Yifei Zhang
摘要： Plasma frequency is the spectral boundary for low-loss propagation and evanescent decay of surface plasmon polariton (SPP) waves, which corresponds to a high cut-off phenomenon and is typically utilized for identifying SPPs. At terahertz (THz) frequencies, a metal line with periodic metallic grooves can mimic the conventional optical SPPs, which is referred to as designer SPPs. Theoretically, the plasma frequency of THz SPPs decreases as the groove depth increases. Here, by replacing the metallic grooves with graphene sheets, dynamically sweeping SPP plasma frequency is demonstrated for the first time. The metal-graphene hybrid structure comprises a metal line with periodic graphene grooves, a thin-layer ion gel for gating graphene, and metallic tips for uniforming gate field. As the chemical potential changes, the average conductivity of graphene is modulated so that the effective depth of the graphene grooves changes, which sweeps the plasma frequency of THz SPPs consequently. Both simulated and experimental data demonstrate a red shift of plasma frequency from 195 to 180 GHz at a low bias from -0.5 to 0.5 V. The proposed structure reveals a novel approach to control the on/off status of SPP propagation in the THz range.
点击量
待评议
点击量
下载量
评论
