Abstract

Optical camouflage is a magical capability of animals as first noticed in 1794 by Erasmus Darwin in <em>Zoonomia</em>, but current biomimetic camouflage strategies cannot be readily applied in complex environments involving multispectral and in particular multi-polarization detection. Here we develop a plasmonic approach toward broadband infrared polarimetric crypsis, where the polarized thermal emission near the pseudo-Brewster angle is the main signal source and no existing polarizing camouflage technique has been discovered in nature. Based on all-metallic subwavelength structures, an electrodynamic resistance-reduction mechanism is proposed to avoid the significant polarization-dependent infrared absorption/radiation. It is also found that the structured metal surface presents giant extrinsic anisotropy regarding the phase shift between orthogonal polarization states, which helps to realize ultrahigh-efficiency and tunable polarization conversion in an unprecedented manner. Finally, we note that the catenary optical theory may provide a useful means to explain and predict these unusual performances.

Highlights

  • As one of the most fundamental rules in classical optics, the Fresnel equations, accompanied with Snell’s law, determine the reflection and transmission of light incident on an interface of two media with different refractive indices

  • One important consequence of the Fresnel equations is the Brewster effect, which means the reflectivity for the wave polarized in the plane of incidence (p-polarization) vanishes at a particular incidence angle (Brewster angle)

  • By eliminating the energy loss of surface electromagnetic wave propagating along a structured metallic surface, we show that both the polarimetric thermal emission and laser’s reflection loss can be significantly reduced

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Summary

Introduction

As one of the most fundamental rules in classical optics, the Fresnel equations, accompanied with Snell’s law, determine the reflection and transmission of light incident on an interface of two media with different refractive indices. The reflectivity of p-polarized wave at the Brewster angle would be zero. By eliminating the energy loss of surface electromagnetic wave propagating along a structured metallic surface, we show that both the polarimetric thermal emission and laser’s reflection loss can be significantly reduced.

Results
Conclusion
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