Metamaterials – from fundamentals and MEMS tuning mechanisms to applications

Abstract

Metamaterials, consisting of subwavelength resonant structures, can be artificially engineered to yield desired response to electromagnetic waves. In contrast to the naturally existing materials whose properties are limited by their chemical compositions and structures, the optical response of metamaterials is controlled by the geometrics of resonant unit cells, called “meta-atoms”. Many exotic functionalities such as negative refractive index, cloaking, perfect absorber, have been realized in metamaterials. One recent technical advance in this field is the active metamaterial, in which the structure of metamaterials can be tuned to realize multiple states in a single device. Microelectromechanical systems (MEMS) technology, well-known for its ability of reconfiguring mechanical structures, complementary metal-oxide-semiconductor (CMOS) compatibility and low power consumption, is perfectly suitable for such purpose. In the past one decade, we have seen numerous exciting works endeavoring to incorporate the novel MEMS functionalities with metamaterials for widespread applications. In this review, we will first visit the fundamental theories of MEMS-based active metamaterials, such as the lumped circuit model, coupled-mode theory, and interference theory. Then, we summarize the recent applications of MEMS-based metamaterials in various research fields. Finally, we provide an outlook on the future research directions of MEMS-based metamaterials and their possible applications.

Zero-bias mid-infrared graphene photodetectors with bulk photoresponse and calibration-free polarization detection

“…Metamaterials, the artificial materials with sub-wavelength structures and highly engineered optical properties, offer unique opportunities for optoelectronic devices [21][22][23][24][25][26][27][28][29][30] . Due to the plasmon resonance, the near-field intensity and hence the light absorption can be enhanced by several orders [31][32][33] . Besides, the generated photocarriers may be efficiently collected by the metallic subwavelength structures, which can act as electrodes 34 .…”

Recent Progress in the Energy Harvesting Technology—From Self-Powered Sensors to Self-Sustained IoT, and New Applications

“…As passive platforms, optical gas sensors can be externally probed by laser diodes and, as a result, work as a zero-power sensor node. Absorptive optical sensors have the advantage of label-free analysis capability, arising from the unique characteristic spectrum of a given molecular species [212,213]. This property makes the identification and detection of a complex mixture of different molecules feasible with a straightforward approach.…”

Heterogeneous Wafer Bonding Technology and Thin-Film Transfer Technology-Enabling Platform for the Next Generation Applications beyond 5G

“…Correspondingly, the working wavelengths of many sensors are designed in the range of MIR [ 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 ]. In addition to microelectronics, Si is also one of the most popular materials in photonics [ 171 , 172 ]. Due to its high refractive index, excellent transparent properties in the spectral range from 1.2 μm to 8.0 μm, and high-quality commercial product of SOI platform, all kinds of Si-based sensors have been well developed.…”