Nano-structured anti-reflective surfaces replicated by hot embossing

Dávid, Christian; Häberling, Peter; Schnieper, Marc; Sochtig, J.; Zschokke, Christian

doi:10.1016/s0167-9317(02)00425-2

Cited by 50 publications

(32 citation statements)

References 2 publications

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“…In our experiment, the filling ratio of α-Fe 2 O 3 is 0.3, and the refractive index of the air is 1. If the refractive index of α-Fe 2 O 3 is assumed to be 2.9, according to equation [25],…”

Section: Resultsmentioning

confidence: 99%

Observation of unconventional optical diffraction in α-Fe2O3/Si two-dimensional photonic crystal slab fabricated by sol-gel method

Zhang

Kang

et al. 2012

Appl. Phys. B

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The α-Fe 2 O 3 /Si two-dimensional (2D) photonic crystal (PC) with hexagonal honeycomb structure was fabricated by self-assembly and solution-dipping method based on colloidal monolayer template with 780 and 470 nm diameter polystyrene (PS) spheres. Optical diffraction measurement was carried out under wavelengths of 800, 532 and 400 nm. An interesting dispersion phenomenon with a hexagonal diffraction pattern composed of six elliptical spots is observed under specific wavelengths. Both theoretical and experimental calculations reveal that the diffraction can only occur when the incident wavelength is smaller than √ 3/2 of lattice constant, and both the shape and distribution of these spots can be modified by the PC lattice constant and the incident wavelength. All these results reveal that optical properties of these 2D PC slabs are different from conventional diffractive devices.

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Section: Resultsmentioning

confidence: 99%

Observation of unconventional optical diffraction in α-Fe2O3/Si two-dimensional photonic crystal slab fabricated by sol-gel method

Zhang

Kang

et al. 2012

Appl. Phys. B

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“…In the case of transparent PC and COP materials with refractive indices close to 1.5 [37,38], Fresnel reflection occurs at the air/polymer interface [39], due to the large difference in index values of air and polymer [40]. By patterning the surface of the polymer film with sub-wavelength relief structures with an optimized period, depth and filling factor, the refractive index of air is gradually increased to the value of the employed polymer material, leading to the reduced reflection from the film surface [25,41]. Therefore, in the case of the hot embossed and wrinkle structured PC and COP films, significantly lowered reflectance values over the observed wavelength area can be achieved, when the shape and dimensions of the replicated patterns meet the requirements for AR coating.…”

Section: Surface and Optical Propertiesmentioning

confidence: 99%

“…Hot embossing enables production of different kinds of elements for e.g. optoelectronics or biomedical application purposes [25,26]. Furthermore, the replication, car-95 Low-cost replication of self-organized sub-micron structures into polymer films…”

Section: Introductionmentioning

confidence: 99%

Low-cost replication of self-organized sub-micron structures into polymer films

Stenberg¹,

Stenberg²,

Takkunen³

et al. 2015

Express Polym. Lett.

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Abstract. In this paper, the results of exploiting self-organized sub-micron polystyrene (PS) wrinkle patterns possessing random orientation, in preparation of a nickel stamp for hot embossing purposes, are presented. Self-organized patterns were prepared employing a method in which a stiff cross-linked capping layer on the topmost part of the soft polystyrene layer was created by using reactive ion etching (RIE) device with mild conditions and argon as a process gas, and the wrinkle formation was initiated thermally. Different surface patternings were obtained using silicon and stainless steel (SST) wafers as substrates. Prepared Ni-stamps were employed in hot embossing of polycarbonate (PC) and cyclo-olefin polymer (COP) films, using a nano-imprinting process. The replication quality of the self-organized wrinkle structures in PC and COP films was monitored by comparing the shape and dimensions of the original and final surface structures. The hot embossed sub-micron scale features, originally formed on stainless steel substrate, were found to have influence on the optical properties of the PC and COP films by lowering their reflectances.

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“…Surface-relief gratings with periods smaller than the wavelength of light, named sub-wavelength gratings (SWGs), behave as antireflection surfaces [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The SWGs, particularly one with a tapered line of hole gratings, suppress reflection over wide spectral bandwidth and large field of view.…”

Section: Introductionmentioning

confidence: 99%

“…Gombert et al [10] fabricated a two-dimensional SWG with a 300 nm period grating on organically modified ceramic (ORMOCER) film. David et al [15] fabricated one and two-dimensional SWGs with 200 nm period gratings on polycarbonate. All these experimental demonstrations were based on hot embossing which uses a rigid mold and a heating and cooling process for high pressure imprinting.…”

Section: Introductionmentioning

confidence: 99%