Abstract
Metamaterials integrated with graphene exhibit tremendous freedom in tailoring their optical properties, particularly in the infrared region, and are desired for a wide range of applications, such as thermal imaging, cloaking, and biosensing. In this article, we numerically and experimentally demonstrate an ultrathin (total thickness < λ 0 / 15 ) and electrically tunable mid-infrared perfect absorber based on metal–insulator–metal (MIM) structured metamaterials. The Q-values of the absorber can be tuned through two rather independent parameters, with geometrical structures of metamaterials tuning radiation loss (Qr) of the system and the material loss (tanδ) to further change mainly the intrinsic loss (Qa). This concise mapping of the structural and material properties to resonant mode loss channels enables a two-stage optimization for real applications: geometrical design before fabrication and then electrical tuning as a post-fabrication and fine adjustment knob. As an example, our device demonstrates an electrical and on-site tuning of ~5 dB change in absorption near the perfect absorption region. Our work provides a general guideline for designing and realizing tunable infrared devices and may expand the applications of perfect absorbers for mid-infrared sensors, absorbers, and detectors in extreme spatial-limited circumstances.
Highlights
Metamaterial absorbers are two-dimensional electromagnetic structures absorbing light at the resonance, which have attracted huge attention over the years [1,2,3]
We demonstrate an ultrathin and electrically tunable graphene MIM metamaterial perfect absorber working at the mid-infrared region, with a total thickness of ~270 nm
We studied an ultrathin (< λ0 /15) and electrically tunable graphene metamaterial perfect absorber working at the mid-infrared region
Summary
Metamaterial absorbers are two-dimensional electromagnetic structures absorbing light at the resonance, which have attracted huge attention over the years [1,2,3]. A metamaterial perfect absorber (MPA) based on a metal–insulator–metal (MIM) structure has been a hotspot for researchers due to its near unity absorptivity. By optimizing the periodic subwavelength arrays topping the device, with the bottom layer as effective reflector, near unity absorption can be achieved at its resonance. Different types of perfect absorbers with various metamaterial structures have been widely investigated and analyzed [11,12,13,14,15], the realization of MPA structures typically requires heavy computation and repetitive trial and error experiments to achieve the critical damping condition (i.e., Qr = Qa , where Qr and Qa are quality factors related to radiative loss and intrinsic loss, respectively), because a large amount of geometrical and material parameters are involved and entangled. What’s more, absorbers in extreme forms, like ultrathin and compact absorbers, are desirable for scaling down the device size and/or minimizing parasitic effects, such as thermal leak conductance and large heat capacity for bolometric detector arrays [16,17,18,19,20]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
