Frequency-agile temporal terahertz metamaterials

• Main Authors: Pitchappa, Prakash, Kumar, Abhishek, Liang, Haidong, Prakash, Saurav, Wang, Nan, Bettiol, Andrew A., Venkatesan, Thirumalai, Lee, Chengkuo, Singh, Ranjan
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2020
• Subjects: Physics and Applied Physics; Microelectromechanical Systems; Multifunctional
• Online Access: https://hdl.handle.net/10356/143317
• Institution: Nanyang Technological University

Spatiotemporal manipulation of electromagnetic waves has recently enabled a plethora of exotic optical functionalities, such as non-reciprocity, dynamic wavefront control, unidirectional transmission, linear frequency conversion, and electromagnetic Doppler cloak. Here, an additional dimension is introduced for advanced manipulation of terahertz waves in the space-time, and frequency domains through integration of spatially reconfigurable microelectromechanical systems and photoresponsive material into metamaterials. A large and continuous frequency agility is achieved through movable microcantilevers. The ultrafast resonance modulation occurs upon photoexcitation of ion-irradiated silicon substrate that hosts the microcantilever metamaterial. The fabricated metamaterial switches in 400 ps and provides large spectral tunability of 250 GHz with 100% resonance modulation at each frequency. The integration of perfectly complementing technologies of microelectromechanical systems, femtosecond optical control and ion-irradiated silicon provides unprecedented concurrent control over space, time, and frequency response of metamaterial for designing frequency-agile spatiotemporal modulators, active beamforming, and low-power frequency converters for the next generation terahertz wireless communications.