All-dielectric perfect absorber based on quadrupole modes

Abstract

In principle, the absorbance of a free-standing ultra-thin film is limited to 50%. To overcome this limitation, an all-dielectric perfect absorber is proposed herein based on the concept of degenerate critical coupling (DCC) of quadrupole modes. We study the absorbance of a dielectric elliptic cylinder and find that perfect absorption can be achieved by spectrally overlapping peaks of electric and magnetic quadrupole modes. This suggests that the DCC method can be extended to the quadrupole modes beyond dipole modes. Such an all-dielectric perfect absorber can be used in photodetectors, optical filters, and optical modulators mediated by the photothermal effect.

Mixtures of Multipoles—Should They Be in Your EM Toolbox?

“…Recall that a narrow bandwidth corresponds to a high quality factor Q. High-Q structures are advantageous for filter and absorber designs. A very recent example that uses core-shell multipoles and their high-Q properties to achieve passband filters [84] and another that presents an all-dielectric perfect absorber [269] illustrate this point. A much older example is the use of cylindrical and spherical high-Q cavities as energy storage devices for microwave compression applications associated, for instance, with particle accelerators [270]- [272].…”

“…As noted, dielectric losses are significantly less than metallic ones at optical frequencies. On the other hand, multipolar metastructure examples where the losses are desirable include, for example, color displays [83], high-Q filters [84] and perfect absorbers [67], [85].…”

Plasmonic Perfect Absorber Utilizing Polyhexamethylene Biguanide Polymer for Carbon Dioxide Gas Sensing Application

“…Moreover, it is shown through research work performed in the areas of perfect absorbers that the material may or may not always comprise MIM sequence as well, as studied in [ 27 ], using a dielectric material and a vertical double-pillars sequence of meta-molecules covered by a layer of Au. Therefore, single materials with designing techniques can also harness useful properties, as proven in [ 28 ], using a mechanism of degenerate critical coupling (DCC) and quadrupole modes, which have thus led to the creation of diverse applications in the field of sensing, such as plasmonics-based sensors [ 29 ], refractive index-based sensors [ 30 ], and temperature sensors, all by employing the phenomena of enhanced-optical utilization [ 31 ], time-reversed lasers [ 32 ], and thin-layered structures [ 33 ].…”

Toroidal Dipole-Induced Photocurrent Enhancement in Si Nanodisk Hexagonal Array below the Band Gap

“…According to the coupled mode theory, the absorptance of a single mode resonator is limited to 50% (critical coupling). , Theoretically, near-unity absorption can be achieved if two modes such as electric dipole (ED) and magnetic dipole (MD) modes degenerate. ,, In arrays of amorphous Si nanoparticles, the absorptance as large as 0.83 is achieved by properly controlling the overlap of the ED and MD Mie resonances . Degenerate critical coupling is also studied in the case of electric and magnetic quadrupole modes in a Si nanodisk array . Another interesting approach for absorption enhancement is utilizing an anapole state, which is realized by destructive interference between Cartesian ED and toroidal dipole (TD) modes. , In the anapole state, suppression of far-field radiation results in field confinement in a nanostructure, which induces strong enhancement of light absorption, , nonlinear optical responses, − Raman scattering, photothermal effect, stimulated emission (lasing), photocatalytic effects, and photoelectrode performance …”

“…26 Degenerate critical coupling is also studied in the case of electric and magnetic quadrupole modes in a Si nanodisk array. 27 Another interesting approach for absorption enhancement is utilizing an anapole state, which is realized by destructive interference between Cartesian ED and toroidal dipole (TD) modes. 28,29 In the anapole state, suppression of far-field radiation results in field confinement in a nanostructure, which induces strong enhancement of light absorption, 30,31 nonlinear optical responses, 32−34 Raman scattering, 35 photothermal effect, 36 stimulated emission (lasing), 37 photocatalytic effects, 38 and photoelectrode performance.…”