Random antireflective nanostructuring on binary near-wavelength period gratings

Kunala, Karteek; Poutous, Menelaos K.

doi:10.1117/1.oe.57.8.087106

Cited by 6 publications

(2 citation statements)

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“…These phase boundary effects are due to reactive plasma action, partially etching the side walls during the fabrication of the nanostructures. 22 Any alterations of the DOE transverse feature size and longitudinal phase depth should result in measurable variations of the designed projection patterns and full-field scatter signatures in transmission and reflection. Measurements of these perturbations can give insight into possible undesirable effects of the rARSS on the original DOE profile.…”

Section: Randomly Textured Antireflection Surface Fabricationmentioning

confidence: 99%

Fresnel reflection suppression from deterministic illumination diffusers using antireflection random nanostructures

Gadamsetti

Poutous

2022

Opt. Eng.

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Deterministic illumination diffractive-diffusers have nonperiodic short and mediumscale topography. Because of the deterministic locations of vertical sidewalls at the phase transition boundaries, over-coating diffractive diffusers with thin-film antireflection layers perturbs their function, resulting in performance deviations and nonuniformities. To mitigate these effects, we added antireflection random nanostructures on the surface of three different classes of fused-silica multiphase diffractive diffusers, using reactive-ion plasma etching. The diffusers were measured before and after the random nanostructures addition, using a polarized-laser scatterometer with a dynamic range of nine orders of magnitude. The bidirectional scatter distribution function was measured over the entire equatorial plane of incidence, to analyze the directionality of scattered light and the impact of the antireflective nanostructure presence on the optical performance of the diffusers. The overall reflectivity suppression was measured across the illumination patterns directions, as well as, across the entire 180-deg angle-sweep. The designed deterministic illumination patterns and their contrast were unaffected by the presence of the random antireflective structures, whereas Fresnel reflectivity was reduced by an order of magnitude on average.

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Section: Randomly Textured Antireflection Surface Fabricationmentioning

confidence: 99%

Fresnel reflection suppression from deterministic illumination diffusers using antireflection random nanostructures

Gadamsetti

Poutous

2022

Opt. Eng.

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“…Layered thin-film coatings are commonly used for antireflectivity, but they come with specific challenges when applied to complicated optical surface profiles. As an alternative, random antireflective structured surfaces (rARSS) offer advantages, including broadband antireflectivity, performance insensitivity to polarization and angle of incidence, suppression of directional reflectance and controlled wide-angle scatter, and can be monolithically added to complicated profiles of various components [1][2][3][4][5] . These nanostructured surfaces can be nearly isotropic, dense, and without periodicity or repetitive spatial signatures.…”

Section: Introductionmentioning

confidence: 99%

Shannon’s entropy and structural complexity of random antireflective nanostructures on fused silica surfaces

Srenevas,

Poutous

2023

Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XX

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Over the last decade various researchers have demonstrated optical transmission enhancement for fused silica substrate surfaces using random antireflective structures (rARS). The nano-structured surfaces effectively redirect incident light in the axial transmission direction, thus nearly eliminating Fresnel reflectivity. To quantify relations between the random surface nano-structures and optical performance, statistical analysis of surface heights (roughness) is often used, which can predict scatter but not axial transmission enhancement. The alternate analysis method, using an effective-medium approximation for the surface layer, can predict transmission enhancement using an average refractive index but it fails to determine angular scatter. We characterized rARS surfaces by employing Shannon's entropy, to quantify their randomness through complexity. The objective is to construct a figure-of-merit by studying the distribution, organization, and population density of the nanostructures that result in various scales of reflectivity suppression across the 300 nm to 800 nm spectrum. We fabricated various rARS silica surface modifications, which resulted in different measured spectral transmissions, to examine possible relations between the entropy (order) of the transverse profile feature cross-sections and distributions, with the resulting antireflective functionality. We demonstrate that size-based grouping of spatial data correlates specific transverse-feature population orders to specific transmission enhancements based on a diffractive analysis model.

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Optical Scattering of Deterministic Diffractive Elements with Antireflective Structured Surfaces

Gadamsetti

Kunala

Poutous

2019

2019 IEEE 16th International Conference on Smart Cities: Improving Quality of Life Using ICT &Amp; IoT and AI (HONET-ICT)

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Random antireflective nanostructuring on binary near-wavelength period gratings

Cited by 6 publications

References 0 publications

Fresnel reflection suppression from deterministic illumination diffusers using antireflection random nanostructures

Fresnel reflection suppression from deterministic illumination diffusers using antireflection random nanostructures

Shannon’s entropy and structural complexity of random antireflective nanostructures on fused silica surfaces

Optical Scattering of Deterministic Diffractive Elements with Antireflective Structured Surfaces

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