Narrow band perfect absorber for maximum localized magnetic and electric field enhancement and sensing applications

Abstract

Plasmonics offer an exciting way to mediate the interaction between light and matter, allowing strong field enhancement and confinement, large absorption and scattering at resonance. However, simultaneous realization of ultra-narrow band perfect absorption and electromagnetic field enhancement is challenging due to the intrinsic high optical losses and radiative damping in metals. Here, we propose an all-metal plasmonic absorber with an absorption bandwidth less than 8 nm and polarization insensitive absorptivity exceeding 99%. Unlike traditional Metal-Dielectric-Metal configurations, we demonstrate that the narrowband perfect absorption and field enhancement are ascribed to the vertical gap plasmonic mode in the deep subwavelength scale, which has a high quality factor of 120 and mode volume of about 10−4 × (λres/n)3. Based on the coupled mode theory, we verify that the diluted field enhancement is proportional to the absorption, and thus perfect absorption is critical to maximum field enhancement. In addition, the proposed perfect absorber can be operated as a refractive index sensor with a sensitivity of 885 nm/RIU and figure of merit as high as 110. It provides a new design strategy for narrow band perfect absorption and local field enhancement, and has potential applications in biosensors, filters and nonlinear optics.

Highly Flexible and Voltage Based Wavelength Tunable Biosensor

“…Recent interest in perfect absorbers comes from the advances that allow scientists to apply structured and characterized metals for absorption purposes in the nanometer scale. This, in turn, has enabled us to explore their potential applications in optics, solar cells selective thermal emitters filters and sensors for detecting bio‐molecules . For instance, perfect absorption has been reported in different materials including gold, silver, and aluminum .…”

Plasmonic metamaterial for electromagnetically induced transparency analogue and ultra-high figure of merit sensor

“…Furthermore, the designed structure can be worked as a refractive index sensor using the resonance dip resulting from surface plasmon polarizations (SPP) in near-infrared region. This plasmonic nanostructure shows an excellent sensing performance with an ultra-high FOM of 3200, which greatly improves the FOM value compared with previously reported refractive index sensor based on plasmonic metamaterials34353637383940414243444546474849. Although the improvement of FOM has already attracted considerable attention among many researchers, it is still a challenge to design a plasmonic refractive index sensor with an ultra-high FOM.…”

Heavily Doped Semiconductor Metamaterials for Mid‐Infrared Multispectral Perfect Absorption and Thermal Emission

“…An equivalent description of the perfect absorption process can be given in terms of destructive interference of incoming and outgoing waves to minimize reflection . Applications of MPAs range from bolometers or more generally thermal detectors and thermal emitters, antireflection coatings and stealth technology, spatial light modulators for imaging, to refractive index, gas, and biochemical sensors . For these applications, MPAs for diverse parts of the electromagnetic spectrum from the optical to the microwave regime are required.…”