Ultrafast Terahertz Self-Induced Absorption and Phase Modulation on a Graphene-Based Thin Film Absorber,ACS Photonics

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Ultrafast Terahertz Self-Induced Absorption and Phase Modulation on a Graphene-Based Thin Film Absorber
ACS Photonics ( IF 6.5 ) Pub Date : 2022-09-08 , DOI: 10.1021/acsphotonics.2c00828
Anastasios D. Koulouklidis ₁ , Anna C. Tasolamprou ₁ , Spyros Doukas ₂ , Eudokia Kyriakou _{1,

3} , M. Said Ergoktas _{4,

5} , Christina Daskalaki ₁ , Eleftherios N. Economou _{1,

6} , Coskun Kocabas _{4,

5,

7} , Elefterios Lidorikis _{2,

8} , Maria Kafesaki _{1,

3} , Stelios Tzortzakis _{1,

3,

9}

Affiliation

Interaction of intense terahertz (THz) waves with graphene based modulation devices holds great potential for the optoelectronic applications of the future. Here, we present a thin film graphene-based THz perfect absorbing device whose absorption and phase characteristics can be modulated through THz self-actions in the subps time scale. The device consists of a single-layer graphene placed on an ionic liquid substrate, back-plated by a metallic back-reflector, with the graphene doping level mediated through electrostatic gating. We experimentally record an absorption modulation of more than 3 orders of magnitude from the initial perfect absorption state, when the device is illuminated with THz field strengths in the range of 102 to 654 kV/cm. Furthermore, an absolute phase modulation of 130° is recorded. Detailed theoretical analysis indicates that the origin of the THz nonlinear response is the THz-induced heating of the graphene’s carriers that leads to a reduction of its conductivity and, consequently, to reduced absorption of the THz radiation. Our analysis also maps the temporal dynamics of the THz-induced temperature elevation of the graphene’s carriers, illustrating the ultrafast, subps nature of the overall process. These results can find applications in future dynamically controlled flat optics and spatiotemporal shaping of intense THz electric fields.

中文翻译：

石墨烯基薄膜吸收器上的超快太赫兹自感应吸收和相位调制

强太赫兹 (THz) 波与基于石墨烯的调制器件的相互作用对于未来的光电应用具有巨大的潜力。在这里，我们提出了一种基于薄膜石墨烯的太赫兹完美吸收器件，其吸收和相位特性可以通过亚皮秒时间尺度内的太赫兹自作用进行调制。该器件由放置在离子液体基板上的单层石墨烯组成，背面镀有金属背反射器，石墨烯掺杂水平通过静电门控调节。当设备以 102 至 654 kV/cm 范围内的太赫兹场强照射时，我们通过实验记录了从初始完美吸收状态超过 3 个数量级的吸收调制。此外，记录了 130° 的绝对相位调制。详细的理论分析表明，太赫兹非线性响应的起源是太赫兹引起的石墨烯载流子加热，导致其电导率降低，从而导致太赫兹辐射的吸收减少。我们的分析还绘制了太赫兹引起的石墨烯载流子温度升高的时间动态，说明了整个过程的超快、亚微秒性质。这些结果可以在未来的动态控制平面光学和强太赫兹电场的时空整形中找到应用。我们的分析还绘制了太赫兹引起的石墨烯载流子温度升高的时间动态，说明了整个过程的超快、亚微秒性质。这些结果可以在未来的动态控制平面光学和强太赫兹电场的时空整形中找到应用。我们的分析还绘制了太赫兹引起的石墨烯载流子温度升高的时间动态，说明了整个过程的超快、亚微秒性质。这些结果可以在未来的动态控制平面光学和强太赫兹电场的时空整形中找到应用。

更新日期：2022-09-08

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