Optimal design for antireflective tapered two-dimensional subwavelength grating structures

Grann, Eric B.; Moharam, M. G.; Pommet, Drew A.

doi:10.1364/josaa.12.000333

Cited by 241 publications

(132 citation statements)

References 19 publications

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“…Since the grating is obliquely cut at the boundary of the cloak, some diffraction will occur at the interface, which may also contribute to the reduced transmission. Consequently, adding an index matching layer [25,26] around the cloak, reducing the pitch and improving the uniformity of the grating would help eliminate the reflection, diffraction and scattering effect. In our experiment, the ratio of the size (area) of the bump to that of the cloak device is 0.23.…”

Section: Resultsmentioning

confidence: 99%

Homogeneous optical cloak constructed with uniform layered structures

Zhang¹,

Liu²,

Luo³

et al. 2011

Opt. Express

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Abstract:The prospect of rendering objects invisible has intrigued researchers for centuries. Transformation optics based invisibility cloak design is now bringing this goal from science fictions to reality and has already been demonstrated experimentally in microwave and optical frequencies. However, the majority of the invisibility cloaks reported so far have a spatially varying refractive index which requires complicated design processes. Besides, the size of the hidden object is usually small relative to that of the cloak device. Here we report the experimental realization of a homogenous invisibility cloak with a uniform silicon grating structure. The design strategy eliminates the need for spatial variation of the material index, and in terms of size it allows for a very large obstacle/cloak ratio. A broadband invisibility behavior has been verified at near-infrared frequencies, opening up new opportunities for using uniform layered medium to realize invisibility at any frequency ranges, where high-quality dielectrics are available.

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Section: Resultsmentioning

confidence: 99%

Homogeneous optical cloak constructed with uniform layered structures

Zhang¹,

Liu²,

Luo³

et al. 2011

Opt. Express

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“…This gradual approach with subwavelength features is useful as an effective antireflection coating with broadband transmission. 3,[27][28][29] For the metal back grating we also use a triangular geometry, as we previously demonstrated a flexible scattering capability and beneficial field distribution of SPP modes. 15 Basic design guidelines for the dimensions of the grating structures for placing waveguide and SPP mode resonances are obtained by folded dispersion diagrams.…”

Section: Design Strategymentioning

confidence: 99%

Dual-interface gratings for broadband absorption enhancement in thin-film solar cells

Abass

Alù

et al. 2012

Phys. Rev. B

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We numerically study complex dual-interface grating systems to enhance absorption efficiency in thin-film silicon solar cells. We combine a plasmonic grating at the back side of the solar cell with a dielectric grating at the front side of the cell. We show a proof of principle, with one-dimensional gratings, that the distinctly different nature of the gratings can provide complementary enhancement mechanisms, which we further exploit by tailoring the specific periodicities, and by introducing blazing. Having different periods at specific interfaces allows for more efficient diffraction into both plasmonic and dielectric guided modes. In addition, grating specific blazing exposes extra modes to normal incident light through symmetry breaking. Multiple optimization routes are possible depending on the choice of photonic phenomena.

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“…In the present work, we theoretically investigated how antireflective sub-wavelength structures affect the white light spectrum generated by Kamiyama LED in respects of the light extraction efficiency, color rendering index, and correlated color temperature. Both cylinder and moth-eye structures have been studied in the simulation based on the rigorous coupled wave analysis algorithm [20].…”

Section: Introductionmentioning

confidence: 99%