提出一种石墨烯-金属超材料复合太赫兹传感器，充分利用石墨烯能带Dirac点附近费米能级对样品的灵敏响应结合超材料表面强局域电场实现了对谷氨酸溶液浓度的多维超灵敏传感。实验结果表明，传感器在频率f =0.58 THz处存在一个明显的透射峰，且该透射峰幅值随谷氨酸溶液浓度的增加先升高后降低。若以透射峰幅值作为传感指标，器件能够探测到的最低浓度在10⁻¹ fg/mL量级。另外，从传感器的透射波相位差-频率关系曲线中提取的斜率与浓度具有类线性关联，这意味着相位差信息也可以作为有效的传感指标。结合透射幅值和相位差两个传感指标，器件可以实现对谷氨酸溶液浓度的超灵敏精确检测。文中提出的器件为发展基于太赫兹超材料的超灵敏氨基酸传感器提供了帮助。

Integrating novel materials is critical for the ultrasensitive, multi-dimensional detection of biomolecules in the terahertz (THz) range. Few studies on THz biosensors have used semiconductive active layers with tunable energy band structures. In this study, we demonstrate three THz biosensors for detecting casein molecules based on the hybridization of the metasurface with graphitic carbon nitride, graphene, and heterojunction. We achieved low-concentration detection of casein molecules with a 3.54 ng/mL limit and multi-dimensional sensing by observing three degrees of variations (frequency shift, transmission difference, and phase difference). The favorable effect of casein on the conductivity of the semiconductive active layer can be used to explain the internal sensing mechanism. The incorporation of protein molecules changes the carrier concentration on the surface of the semiconductor active layer via the electrostatic doping effect as the concentration of positively charged casein grows, which alters the energy band structure and the conductivity of the active layer. The measured results indicate that any casein concentration can be distinguished directly by observing variations in resonance frequency, transmission value, and phase difference. With the heterojunction, the biosensor showed the highest response to the protein among the three biosensors. The Silvaco Atlas package was used to simulate the three samples’ energy band structure and carrier transport to demonstrate the benefits of the heterojunction for the sensor. The simulation results validated our proposed theoretical mechanism model. Our proposed biosensors could provide a novel approach for THz metasurface-based ultrasensitive biosensing technologies.

Active control of the electromagnetically induced transparency (EIT) analog is desirable in photonics development. Here, we theoretically and experimentally proposed a novel terahertz (THz) asymmetric metasurface structure that can possess high-sensitivity modulation under extremely low power density by integrating perovskite or graphene. Using the novel metasurface structure with the perovskite coating, the maximum amplitude modulation depth (AMD) of this perovskite-based device reached 490.53% at a low power density of 12.8037mW/cm2. In addition, after the novel THz metasurface structure was combined with graphene, this graphene-based device also achieved high AMD with the maximum AMD being 180.56% at 16.312mW/cm2, and its transmission amplitude could be electrically driven at a low bias voltage. The physical origin of this modulation was explained using a two-oscillator EIT model. This work provides a promising platform for developing high-sensitivity THz sensors, light modulators, and switches.

针对传统图形化工艺复杂且图形未经精细设计，导致电场分布不均匀的问题，通过ANSYS Maxwell 16.0仿真软件研究电子运动轨迹规律，提出图形化发射体阵列有效发射尺寸和最佳阵列间距阴极结构的新思路，改善场发射性能。仿真结果表明，当阵列间距为200 μm时，图形化阵列中心区域的电场分布平坦，阵列四周突变上升。这是由于阵列边缘部分相比于阵列中心区域部分更表现出针尖的特性，当阵列间距越小时，单元阵列之间的边缘区域场强叠加，出现场强叠加区。当阵列间距逐渐增大时，场强边缘叠加效应削弱，同时电场屏蔽效应也削弱。因此，阵列边长越大，为400 μm时，阴极表面场强趋于平坦，场强边缘叠加效应和电场屏蔽效应达到平衡。而阵列间距增大到600 μm时，会导致单元阵列平面中心位置相对较远，单元阵列场发射相对独立，电子发射出现空档区域。因此，阵列间距选取适中数值时，阵列边缘场强叠加效应削弱，四周电场也不会出现盲区，电场基本达到均匀分布。根据仿真结果，通过喷墨打印图形化种子层实现图案化发射体阵列精准定位，再水热生长ZnO纳米棒阴极阵列。场致发射实验结果表明，随着间距的增加，开启场强E_on从200 μm时的2.95 V/μm降低到400 μm时的0.57 V/μm，并进一步变为600 μm时的2.26 V/μm；而场增强因子β随阵列间距从200 μm增加到600 μm，先增大后减小。这与仿真结果吻合，即在ZnO阴极阵列有效发射尺寸为200 μm情况下，当阵列间距为400 μm时，场发射性能最优，其开启场强为0.57 V/μm，场发射增强因子为32 179。通过调控图形化阵列电子发射轨迹，从而减小场叠加和场屏蔽效应可以改善场发射性能。结合图形化设计和喷墨打印的高效性，有望实现高性能场致发射电子源。

利用高能量纳秒激光轰击Al靶材产生的X射线作为信号源，对光折变X射线半导体响应芯片的空间性能进行实验研究。结果表明，低温生长AlGaAs芯片具备在X射线入射能量120∶1的动态范围内进行高空间分辨的大画幅成像能力，最优空间分辨率≥35 lp/mm @MTF=0.1，成像画幅可达6.7 mm×6.7 mm。该研究对于光折变X射线超快成像系统的研制具有参考意义。