Chanana Ashish, Liu Xiaojie, Zhang Chuang, Vardeny Zeev Valy, Nahata Ajay
Department of Electrical and Computer Engineering, 50 S. Central Campus Drive, University of Utah, Salt Lake City, UT 84112, USA.
Department of Physics and Astronomy, 115 S. 1400 East, University of Utah, Salt Lake City, UT 84112, USA.
Sci Adv. 2018 May 4;4(5):eaar7353. doi: 10.1126/sciadv.aar7353. eCollection 2018 May.
The ability to control the response of metamaterial structures can facilitate the development of new terahertz devices, with applications in spectroscopy and communications. We demonstrate ultrafast frequency-agile terahertz metamaterial devices that enable such a capability, in which multiple perovskites can be patterned in each unit cell with micrometer-scale precision. To accomplish this, we developed a fabrication technique that shields already deposited perovskites from organic solvents, allowing for multiple perovskites to be patterned in close proximity. By doing so, we demonstrate tuning of the terahertz resonant response that is based not only on the optical pump fluence but also on the optical wavelength. Because polycrystalline perovskites have subnanosecond photocarrier recombination lifetimes, switching between resonances can occur on an ultrafast time scale. The use of multiple perovskites allows for new functionalities that are not possible using a single semiconducting material. For example, by patterning one perovskite in the gaps of split-ring resonators and bringing a uniform thin film of a second perovskite in close proximity, we demonstrate tuning of the resonant response using one optical wavelength and suppression of the resonance using a different optical wavelength. This general approach offers new capabilities for creating tunable terahertz devices.
控制超材料结构响应的能力有助于新型太赫兹器件的开发，这些器件可应用于光谱学和通信领域。我们展示了具有这种能力的超快频率捷变太赫兹超材料器件，其中每个单元胞中的多个钙钛矿可以以微米级精度进行图案化。为实现这一点，我们开发了一种制造技术，该技术可保护已沉积的钙钛矿免受有机溶剂影响，从而允许在紧邻位置对多个钙钛矿进行图案化。通过这样做，我们展示了太赫兹共振响应的调谐，其不仅基于光泵浦通量，还基于光波长。由于多晶钙钛矿具有亚纳秒级的光载流子复合寿命，因此共振之间的切换可以在超快时间尺度上发生。使用多个钙钛矿可实现使用单一半导体材料无法实现的新功能。例如，通过在裂环谐振器的间隙中图案化一种钙钛矿，并使第二种钙钛矿的均匀薄膜紧邻放置，我们展示了使用一种光波长调谐共振响应以及使用不同光波长抑制共振的方法。这种通用方法为创建可调谐太赫兹器件提供了新能力。
