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In the past, the polarization-insensitive absorption is realized mainly employing the two-dimensional periodic structure of fourfold rotational symmetry, which greatly increases the manufacturing complexity and cost. Here, we present the numerical design of a polarization-independent near-perfect absorber incorporating one-dimensional embedded aluminum grating. The absorption peaks near 99% at 520-nm wavelength for different polarization angles are achieved. The underlying mechanism associated with the resonance is attributed to the magnetic polariton resonance and the cavity-mode resonance for TM and TE polarization, respectively, and further explained by the inductor-capacitor circuit model and the eigen equation of cavity mode. Furthermore, the effects of geometrical parameters of the nano-cavity on the absorption performance are discussed. The proposed structure may provide a new way to achieve polarization-independent absorption with one-dimensional meta-surface, which has broad applications in plasmonic sensors, photo-detectors, and so on.

We present a polarization-independent near-perfect absorber in the visible regime based on one-dimensional meta-surface. In this absorber, the dielectric grating layer with high refractive index is essential, which supports strongly localized electromagnetic modes concentrated in the double-metal regions. The simulation results show that absorption peaks are over 99% at the wavelength of 0.45 μm for both TM and TE polarizations. The near-perfect absorptions are attributed to the lateral plasmon cavity resonance and longitudinal Fabry-Perot-like cavity resonance for TM and TE polarization, respectively. Furthermore, theses absorption peaks can maintain almost unchanged within wide ranges of incident and azimuthal angles. Comparing with those meta-material absorbers with complex two-dimensional array and one-dimensional stacked array, this one-dimensional absorber has a very simple geometrical structure which can be integrated into complex photonic devices expediently.

We design and numerically investigate an optical absorber consisting of the sub-wavelength dielectric grating covered by continuous thin aluminum film. In this absorber, the aluminum film act as an efficient absorbing material because of the enhanced electric field in the air nano-grooves, and the absorption spect+rum can be manipulated by Fabry-Perot cavity mode resonance. According to the spectrum manipulation mechanism, the wavelength of absorption peak can be tuned by changing the heights and widths of the air nano-grooves. More importantly, the high absorption is very robust to the incident angle around the designed wavelength. From the nanofabrication point of view, the light absorber can be fabricated more easily without the need for ion or electrochemical etching of metal and it is easy to be integrated into complex photonic devices.