Multifunctional Hybrid Metasurfaces for Dynamic Tuning of Terahertz Waves

Abstract

Actively tuning optical transmission through hybrid metasurfaces incorporated with multifunctional active media holds great promise for the next generation optical devices. In the terahertz (THz) range, they remain rare due to the lack of dynamic and multifunctional designs and materials. Here, a vanadium dioxide (VO2)‐based hybrid metasurface is proposed to present multifunctional control of THz waves via electrically triggering and ultrafast optical excitation. By minimizing the thermal mass of VO2 and optimizing the VO2 patterns within two side gaps of the asymmetric split‐ring resonators, a hybrid metasurface which can tune the THz wave with an absolute modulation depth up to 54% and a figure of merit as high as 138% is hereby presented. The hybrid metasurface achieves a switching time of 2.2 s under the electrically triggering and offers an ultrafast modulation within 30 ps under the femtosecond pulse excitation. More interestingly, owing to the intrinsic hysteresis behavior of VO2, the hybrid metasurface exhibits distinguishing multistate transmission amplitudes with a single electrical input. In short, this study paves the way for robust multifunctionality in electric‐controlled terahertz switching, photonic memory, and ultrafast terahertz optics.

Chalcogenide Phase Change Material for Active Terahertz Photonics

“…Furthermore, these active materials are usually responsive to a single driving field, one of electrical, thermal, or optical stimulus, which hinders their applicability for multidimensional manipulation of terahertz waves. Phase change materials with contrasting material properties at different crystallographic phases would be an ideal material platform for the realization of multifunctional terahertz metadevices . The most popular choice among phase change materials for terahertz metadevices has been vanadium dioxide (VO 2 ), which has been exploited for varied functionalities enabled by its hysteretic insulator to metal phase transition .…”

“…The most popular choice among phase change materials for terahertz metadevices has been vanadium dioxide (VO 2 ), which has been exploited for varied functionalities enabled by its hysteretic insulator to metal phase transition . However, the practical applicability of VO 2 for terahertz metadevices is hindered by its limited multilevel response, nonvolatility at elevated temperature, predefined singular ultrafast optical response, and complexity of fabrication …”

Dynamic Terahertz Plasmonics Enabled by Phase‐Change Materials

“…[76,81,[86][87][88][89][90][91][92][93][94][95][96][97][98][99] The early demonstration of a THz metamaterial made of VO 2 involved an array of cut-wire-type resonators without any metal structures (Figure 7a). Instead of thin films, small pieces of VO 2 are integrated into metamaterial designs as a part of resonators so that the resonance properties can be directly tuned by controlling the IMT.…”

“…[96] When asymmetric SRRs whose two gaps are filled with VO 2 are connected in parallel (Figure 8a), the resonance peak can be redshifted by applying a current ( Figure 8b). [96] When asymmetric SRRs whose two gaps are filled with VO 2 are connected in parallel (Figure 8a), the resonance peak can be redshifted by applying a current ( Figure 8b).…”

Terahertz transmission properties of vanadium dioxide films deposited on gold grating structure with different periods

“…This phase change property can be triggered on a sub-picosecond timescale by different external conditions, including temperature, stress, electromagnetic field, light, etc [28][29][30]. Due to its unique property, it is potential for the design of logic storage devices [31,32], switching devices [33,34], modulators [35,36] and many other devices. Utilizing this material, the transmission of electromagnetic waves can be continuously and spontaneously tuned by means of temperature control over a wide spectral range, and thus VO 2 gives rise to great possibilities in the field of electromagnetic wave modulation and switching devices.…”