Suppression of backscattered diffraction from sub-wavelength ‘moth-eye’ arrays

Abstract

Abstract:The eyes and wings of some species of moth are covered with arrays of nanoscale features that dramatically reduce reflection of light. There have been multiple examples where this approach has been adapted for use in antireflection and antiglare technologies with the fabrication of artificial moth-eye surfaces. In this work, the suppression of iridescence caused by the diffraction of light from such artificial regular moth-eye arrays at high angles of incidence is achieved with the use of a new tiled domain design, inspired by the arrangement of features on natural moth-eye surfaces. This bio-mimetic pillar architecture contains high optical rotational symmetry and can achieve high levels of diffraction order power reduction. For example, a tiled design fabricated in silicon and consisting of domains with 9 different orientations of the traditional hexagonal array exhibited a ~96% reduction in the intensity of the −1 diffraction order. It is suggested natural moth-eye surfaces have evolved a tiled domain structure as it confers efficient antireflection whilst avoiding problems with high angle diffraction. This combination of antireflection and stealth properties increases chances of survival by reducing the risk of the insect being spotted by a predator. Furthermore, the tiled domain design could lead to more effective artificial moth-eye arrays for antiglare and stealth applications. 1142-1146 (1987). 9. S. J. Wilson and M. C. Hutley, "The optical properties of "moth eye" antireflection surfaces," Opt. Acta (Lond.) 29(7), 993-1009 (1982). 10. R. C. Enger and S. K. Case, "Optical elements with ultrahigh spatial-frequency surface corrugations," Appl. Opt. 3220-3228 (1983). 11. K. M. Baker, "Highly corrected close-packed microlens arrays and moth-eye structuring on curved surfaces," Appl. Opt. 38(2), 352-356 (1999 53-56 (1997). 19. D. L. Brundrett, T. K. Gaylord, and E. N. Glytsis, "Polarizing mirror/absorber for visible wavelengths based on a silicon subwavelength grating: design and fabrication," Appl. Opt. 37(13), 2534-2541 (1998). 20. Y. Kanamori, K. Hane, H. Sai, and H. Yugami, "100 nm period silicon antireflection structures fabricated using a porous alumina membrane mask," Appl. Phys. Lett. 22(20),

Importance of diffuse scattering phenomena in moth-eye arrays for broadband infrared applications

“…An alternative approach to ARCs can be found in the eye of the moth [10][11][12][13][14], where sub-λ protuberances on the eye surface present a smooth refractive index gradient, i.e., from n 1 in air to n 1.4 in the eye tissue, that decreases Fresnel reflection and diffraction. Since protuberances are smaller than the wavelength, the outer layer of the eye behaves as an effective medium with spatially varying refractive index that suppress reflection, making the air-eye interface essentially disappear.…”

“…These benefits have been leveraged heavily at visible wavelengths to create ME-based antiglare coatings for displays and windows [12,17], increase light collection in solar cells [5,18], and increase light extraction in light-emitting diodes (LEDs) [19]. ME arrays are typically characterized with direct transmission and specular reflectance measurements [8], which give a good idea of optical performance.…”

Biomimetic ‘moth-eye’ anti-reflection boundary for graphene plasmons circuits

“…The investigations of such biological systems provide a great number of photonic design opportunities [5][6][7], e.g. the designs of some highly selective vapor sensors are inspired by the Morpho butterfly wing structures, and the eyes or wings of some species of moth are covered with arrays of nanoscale features that dramatically reduce reflection of light [8]. Multiple examples are proposed where this approach has been adapted for use in antireflection and antiglare technologies with the fabrication of artificial moth-eye surfaces [9,10].…”

Bio-inspired, sub-wavelength surface structures for ultra-broadband, omni-directional anti-reflection in the mid and far IR

“…1], this effect is achieved by tissue protuberances with a sinusoidal height profile that reduce reflection in the visible and NIR. In addition, the quasi-ordered nature of the protuberance array suppresses diffraction and camouflages the moth from predators [11]. The moth-eye (ME) principle, in theory, can be used with any material platform to achieve the same effect by scaling the pitch and size of protuberances for the wavelength range of interest.…”