Rolic Ag

Csem Centre Suisse D'electronique Et De Microtechnique Sa&#x2014;recherche Et D&#xe9;veloppement

Csem Centre Suisse D'electronique Et De Microtechnique Sa - Recherche Et Developpment

Csem Centre Suisse D'electronique Et De Microtechnique Sa

Rolic Technologies Ag

Martin Stalder

Martin Schadt

Guillaume Basset

Peter Seitz

Mohammed Ibn-Elhaj

Franco Moia

David Pires

J&uuml;rg F&uuml;nfschilling

Fabian Lutolf

Omar Sqalli

The present invention relates to an element comprising a surface area with a specific, optically effective surface relief microstructure (). The surface relief microstructure has a surface modulation of top regions () and bottom regions (), wherein in a first lateral direction of the surface area there is in average at least one transition from a top to a bottom region or vice versa within every 20 micrometer, and in a second lateral direction of the mask, which is perpendicular to the first direction, there is in average at least one transition from a first to a second zone or vice versa within every 200 micrometer. In the microstructure, (i) in the first direction the lateral arrangement of the transitions is non-periodic, and (ii) the top regions substantially lie in the same top relief plateau () and the bottom regions substantially lie in the same bottom relief plateau ().

Optically effective surface relief microstructures and method of making them

The present invention concerns a method for constructing a light coupling system wherein a grating is manufactured on the surface of a multimode waveguide and defines the entrance of the waveguide for an incident light beam, said grating comprising a repetition of patterns. The grating is defined by a set of parameters comprising: &#x2022;grating period (P), separating two adjacent patterns, &#x2022;grating depth (d) between the highest and the lowest point of the pattern, &#x2022;incident angle mean value (&#x3b8;) of the incident light with respect to the waveguide. The method comprises a step of optimization of the set of parameters to obtain an optimized second set of parameters, in order to obtain a transmission efficiency (Ce) of the incident light into said waveguide for the first or the second diffractive order exceeding 35% for unpolarized light, or exceeding 50% for polarized light, at a given wavelength of the incident light.

Method to optimize a light coupling waveguide

The invention relates to a grating coupler comprising: &#x2014;an optical substrate arranged to transfer a light beam, and &#x2014;a diffraction grating arranged on, or imbedded in, the surface of said optical substrate, said diffraction grating comprising diffraction grating elements comprising each a coating arranged asymmetrically on said diffraction grating elements. The grating coupler is further arranged to satisfy the condition: (n1&#xd7;sin(I&#x3b1;I)+&#x3b7;2)/&#x3bb;&#xd7;P&#x3e;1, wherein n1 is the refractive index of the optical medium to the incident light side of the diffraction grating elements, n2 is the refractive index of the optical medium to the diffracted light side of the diffraction grating elements, lal the absolute value of the incident angle of the light beam incident on the grating coupler &#x3bb; is the vacuum wavelength of the diffracted light, and P is the period of the diffraction grating elements.

Optical grating coupling structure

The present invention relates to an element comprising a surface area with a specific, optically effective surface relief microstructure (). The surface relief microstructure has a surface modulation of top regions () and bottom regions (), wherein in a first lateral direction of the surface area there is in average at least one transition from a top to a bottom region or vice versa within every 20 micrometer, and in a second lateral direction of the mask, which is perpendicular to the first direction, there is in average at least one transition from a first to a second zone or vice versa within every 200 micrometer. In the microstructure, (i) in the first direction the lateral arrangement of the transitions is non-periodic, and (ii) the top regions substantially lie in the same top relief plateau () and the bottom regions substantially lie in the same bottom relief plateau (). Through scattering effects, the surface relief microstructures are suitable to display images with a positive-negative image flip, which advantageously have a distinct and saturated color appearance but at the same time do not show any rainbow colors. The invention also relates to methods for making such elements as well as to security devices comprising such elements.

The present invention relates to a new optical component comprising an anisotropic diffuser () with patterned anisotropy; and means () for providing a colorshift observable upon changing viewing angle () and/or changing angle of incident light (). It also relates to methods for making such an optical component and uses of such optical components as security elements with a very high level of security.

Anisotropic optical device with varying local imagewise and method for making same

A liquid crystal electrooptical element is disclosed that comprises a pair of substrates positioned between a pair of polarising plates, electrodes defining pixel areas and alignment layers disposed on the respective opposing inside surfaces of the substrates, and a chiral nematic liquid crystal sandwiched between the pair of surfaces. At least one of the alignment layers may be patterned in such a way that the azimuth or pretilt or both alignment directions are different at the substrate interfaces suppressing the growth of the ground state of the liquid crystal. When an initial electrical pulse is applied, one of the at least two bistable states can be reached, wherein the contrast ratio between the bistable states is two or greater. A device with such features is long-term bistable and does not require electronic refreshing as long as the displayed information is not changed. Therefore, the power consumption of this bistable device is minimal.

Nematic liquid crystal electrooptical element and device

A liquid crystal device comprising ferroelectric liquid crystal material aligned by a liquid crystal polymer (LCP) network layer ( ) under 20 nm thick, which itself was aligned by a photo-oriented linearly photopolymerized (LPP) layer ( ) under 20 nm thick, exhibits low voltage drop over the aligning layer and has a remarkable contrast ratio.

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Oberwil, Switzerland

Martin Stalder