A Flexible and Ultra‐Wideband Terahertz Wave Absorber Based on Pyramid‐Shaped Carbon Nanotube Array via Femtosecond‐Laser Microprocessing and Two‐Step Transfer Technique

Abstract

With the advances in THz technologies, THz functional devices and integrated systems put forward higher requirements for the development of filters, attenuators and absorbers, whose performance is dependent on the absorption characteristics of the device to the incident THz waves. [12] Therefore, absorbers have gained much interests among THz devices, and become one of the most important components for the applications mentioned above. Wide bandwidth coverage and high power absorptance are critical considerations to evaluate the performances of THz absorbers. These capabilities, however, are not readily available via the use of natural bulk materials. To be more specific, the refractive index of traditional bulk materials is typically greater than unity. [13] For materials that are widely used in THz systems, the refractive index of highresistivity silicon is approximately 3.4, [14] and the values for organic materials such as Polydimethylsiloxane (PDMS), [15,16] Polyethylene terephthalate (PET) and Polymide are between 1.5 and1.8. [17] Therefore, these materials are not ideal for THz absorbers as the former faces considerable surface reflections, [18] while the latter generally have low

Boosting the Electron Beam Transmittance of Field Emission Cathode Using a Self-Charging Gate

“…The CNTs array on Si wafer was synthesized via a thermal chemical vapor deposition (TCVD) system, and the detailed descriptions can be found in the previous report. 94 Prior to the transfer process, the CNTs were heated in the atmosphere at 500℃ for 20 minutes and deposited with Au/Ni/Cr (500/20/50 nm) films on the top side. During the transfer process, the CNTs on Si wafer and another target substrate with patterned Au/Ni/ Cr (500/20/50 nm) on the surface were aligned and placed on the mechanical platform.…”

Flexible Terahertz Metamaterials Absorber based on VO2

“…Such compelling achievements provide superb boilerplates for flexible THz MMAs. Xiao et al propose a flexible and ultra-wideband THz wave absorber that keeps an average power absorptance over 98.9% from 0.1 to 2.5 THz and that can function well in bended states and after 300 times bending cycles [27]. This MMA is expected to be applied to wearable devices, wireless communications and biological sensing due to the flexibility, high-absorptance performance and ultra-wideband operation of the device.…”