Abstract: The security document, such as a passport, comprises a lightguide having an incoupler structure and in outcoupler structure. The outcoupler structure is sparse in the sense that any part of the protective area is close to a part of the outcoupler structure. However, to secure a large protective area with a limited amount of incoupled light, outcoupler structure covers no more than 20% of the protective area. This allows to protect a large area of the security document, such as a photograph or other personalized information, by means of the lightguide.

Abstract: The security document, such as a passport, comprises a lightguide having an incoupler structure and in outcoupler structure. The outcoupler structure is sparse in the sense that any part of the protective area is close to a part of the outcoupler structure. However, to secure a large protective area with a limited amount of incoupled light, outcoupler structure covers no more than 20% of the protective area. This allows to protect a large area of the security document, such as a photograph or other personalized information, by means of the lightguide.

Abstract: The identification document comprises a personalized area carrying owner-specific information, such as an owner's name data or photograph, The personalized area is overlapped by a lightguide, The lightguide comprises a primary incoupler and a primary outcoupler on opposite sides of the personalized area. Any attempt to tamper with the personalized area may lead to a damage in the lightguide, which can easily be detected by coupling light into the primary incoupler and testing the light coupled out by the primary outcoupler.

Abstract: A nano-structured optical wavelength transmission filter is provided. The optical filter includes a patterned substrate on which a high refractive index dielectric waveguide is arranged. A low index dielectric layer is arranged on the high refractive index dielectric waveguide, on which an array of metallic nanostructures is arranged. The layers of the optical filter have conformal shapes defined by a patterned surface of the substrate. An optical filter system includes the optical transmission filter and a detector array fixed to the substrate. A spectrometer includes at least one optical transmission filter and/or at least one said optical transmission filter system, and has a spectral resolution of lower than 30 nm for incident light having a wavelength between 300 nm and 790 nm. A method of fabrication of an optical filter, an optical filter system and a spectrometer is also described.

Abstract: A resonant waveguide grating includes a waveguiding layer and a plurality of subwavelength structures. The waveguiding layer, being in optical proximity to the plurality of subwavelength structures, is configured to guide at most ten wave-guided light modes. The plurality of subwavelength structures includes at least two adjacent grooves having a subwavelength distance between their groove centers being different than the subwavelength distance between the centers of two adjacent ridges. The plurality of subwavelength structures is configured to couple out of the waveguiding layer resonantly by diffraction, an outcoupled fraction of an incoupled portion of incident light. The outcoupled fraction is a diffracted part of an incident light beam. A diffractive optical combiner and a diffractive optical coupler, both include the resonant waveguide grating of the invention. A near-eye display apparatus includes at least the resonant waveguide grating of the invention.

Abstract: An anti-forgery security device comprises an optical waveguide, an out-coupler having first macroscopically repetitive elements and being arranged to couple out light from the waveguide, and a light processing structure comprising second macroscopically repetitive elements and being arranged to process light coupled out by said out-coupler. The first and second elements are arranged on opposite sides of the waveguide. The device generates e.g. Moire and/or parallax effects from light propagating along the waveguide. Third, absorbing elements may be added to generate effects without light in the waveguide.

Abstract: A translucent construction element comprising a layer of translucent substrate, which contains a surface structured with nanoplanes of inclined angle relative to the substrate plane, and coated with an interrupted metallic layer covering at least a part of said nanoplanes, is characterized by a high density of interruptions in the metallic layer of low thickness; the periodicity of interruptions in the metallic layer generally is from the range 50 to 1000 nm and the thickness of the metallic layer typically is from the range 1 to 50 nm. The construction element may be integrated, for example, into windows, plastic films or sheets or glazings, especially for the purpose of light management.

Abstract: An optical combiner including an array of pairs of resonating waveguide gratings. The waveguiding layer of the array, which includes the resonating waveguide gratings, is configured to guide at most ten guided light modes in the visible wavelength range. At least a portion of the resonating waveguide grating array is configured to incouple a portion of incident light on the array and to outcouple a fraction of that incident light. The outcoupled fraction has a predetermined wavelength ? in the visible and near-infrared wavelength range and has a predetermined spectral width ??. The optical combiner is preferably configured to be used in a near-eye display apparatus. The invention is also achieved by a near-eye display apparatus that is adapted to combine projected images provided by a light emitter with light provided by a scene observed by an observer looking through the optical combiner.

Abstract: An ultra-thin spectrometer is disclosed for measuring spectra of a sample, including an optical layer including micro-optical elements having each an input acceptance cone of is less than 30°. At least one of the micro-optical elements is configured to provide a deflected light beam that is directed onto at least one of the photodetectors; The spectrometer includes least one continuous-shaped narrow spectral band filter element arranged between the array of micro-optical elements and the plurality of photodetectors, and defines a plurality of different filter portions that have different peak transmission wavelengths for each of the deflected light beams. The spectral resolution of the spectrometer, in its whole spectral width, is less than 50 nm. Also disclosed is a method to determine the spectrum of an incident light beam on the spectrometer.

Abstract: A resonant waveguide grating includes a waveguiding layer and a plurality of subwavelength structures. The waveguiding layer, being in optical proximity to the plurality of subwavelength structures, is configured to guide at most ten wave-guided light modes. The plurality of subwavelength structures includes at least two adjacent grooves having a subwavelength distance between their groove centers being different than the subwavelength distance between the centers of two adjacent ridges. The plurality of subwavelength structures is configured to couple out of the waveguiding layer resonantly by diffraction, an outcoupled fraction of an incoupled portion of incident light. The outcoupled fraction is a diffracted part of an incident light beam. A diffractive optical combiner and a diffractive optical coupler, both include the resonant waveguide grating of the invention. A near-eye display apparatus includes at least the resonant waveguide grating of the invention.

Abstract: An optical combiner including an array of pairs of resonating waveguide gratings. The waveguiding layer of the array, which includes the resonating waveguide gratings, is configured to guide at most ten guided light modes in the visible wavelength range. At least a portion of the resonating waveguide grating array is configured to incouple a portion of incident light on the array and to outcouple a fraction of that incident light. The outcoupled fraction has a predetermined wavelength ? in the visible and near-infrared wavelength range and has a predetermined spectral width ??. The optical combiner is preferably configured to be used in a near-eye display apparatus. The invention is also achieved by a near-eye display apparatus that is adapted to combine projected images provided by a light emitter with light provided by a scene observed by an observer looking through the optical combiner.

Abstract: A nano-structured optical wavelength transmission filter is provided. The optical filter includes a patterned substrate on which a high refractive index dielectric waveguide is arranged. A low index dielectric layer is arranged on the high refractive index dielectric waveguide, on which an array of metallic nanostructures is arranged. The layers of the optical filter have conformal shapes defined by a patterned surface of the substrate. An optical filter system includes the optical transmission filter and a detector array fixed to the substrate. A spectrometer includes at least one optical transmission filter and/or at least one said optical transmission filter system, and has a spectral resolution of lower than 30 nm for incident light having a wavelength between 300 nm and 790 nm. A method of fabrication of an optical filter, an optical filter system and a spectrometer is also described.

Abstract: A white light source includes an array of light emitting elements arranged to a light guide. A light in-coupling array is arranged so that each light emitting element faces a light in-coupling element to incouple in the light guide a portion of the divergent light beams so that the in-coupled angle of at least a part of the light rays of the in-coupled light beam is higher than 45°. An array of light homogenizing elements is arranged so that each light homogenizing element faces a light incoupling element and so that the deflection angle of at least a fraction of the incident part of the in-coupled light beam incident on each of said homogenizing elements is higher than 45°. The white light source provides a uniform outcoupled white light beam.

Abstract: In the present invention a new atomic clock is proposed comprising: at least one light source adapted to provide an optical beam, at least one photo detector and a vapor cell comprising a first optical window, said optical beam being directed through said vapor cell for providing an optical frequency reference signal, said photo detector being adapted to detect said optical frequency reference signal and to generate at least one reference signal, wherein—said atomic clock comprises a first optical waveguide arranged to said first optical window, said first optical waveguide being arranged to incouple at least a portion of said optical beam, said first optical waveguide being sized and shaped so that said first guided light beam is expanded, a first outcoupler is arranged to outcouple at least a portion of said guided light beam to said vapor cell, —the thickness t of the atomic clock is smaller than 15 nm.

Abstract: A tamper seal includes an optical waveguide arranged to guide a propagating light-beam along a propagation direction. First and second portions of the tamper seal are configured to be arranged on first and second parts, respectively, which are movable relative to each other. The first portion has an input coupler arranged to couple incident light into the optical waveguide, and the second portion has at least one output coupler arranged to couple out of the optical waveguide at least partially light guided in the optical waveguide. The input coupler, the optical waveguide, and the output coupler are configured to transmit light from the input coupler to the output coupler. The waveguide is configured to be disruptable and includes a layer having a distinctive appearance that is changed in response to an at least partial disruption of said optical waveguide.

Abstract: A tamper seal includes an optical waveguide arranged to guide a propagating light-beam along a propagation direction. First and second portions of the tamper seal are configured to be arranged on first and second parts, respectively, which are movable relative to each other. The first portion has an input coupler arranged to couple incident light into the optical waveguide, and the second portion has at least one output coupler arranged to couple out of the optical waveguide at least partially light guided in the optical waveguide. The input coupler, the optical waveguide, and the output coupler are configured to transmit light from the input coupler to the output coupler. The waveguide is configured to be disruptable and includes a layer having a distinctive appearance that is changed in response to an at least partial disruption of said optical waveguide.

Abstract: A guided mode resonance device, comprising—a substrate,—a waveguide,—a grating structure associated with said waveguide, said grating structure being arranged to an incident surface of said substrate, said incident surface being intended to receive an incident light beam provided by at least one light source, said incident light beam having an incident angle, defined relative to the normal of said waveguide, said grating structure comprising at least one elementary structure comprising at least a first-type grating structure and at least a second-type grating structure,—wherein:—said waveguide is arranged to transfer light from the first-type grating structures to the second-type grating structure and also to transfer light from the second-type grating structures to the first-type grating structure,—said first-type grating structure is arranged to couple out a first light beam,—said second-type grating structure is arranged to couple out a second light beam,—said first light beam having a different spectral d

Abstract: An imaging system suitable to provide an image of a surface portion of an object is disclosed. The system includes a light source arranged to provide a light beam, at least a first optical waveguide having a first face and having a second face opposite to the first face, the first face having an incoupling surface. The optical waveguide includes an outcoupling surface, a first diffraction grating arranged on the optical waveguide, and an imaging subsystem arranged to the outcoupling surface. The first diffraction grating is arranged to outcouple at least a fraction of the light beam.

Abstract: A white light source includes an array of light emitting elements arranged to a light guide. A light in-coupling array is arranged so that each light emitting element faces a light in-coupling element to incouple in the light guide a portion of the divergent light beams so that the in-coupled angle of at least a part of the light rays of the in-coupled light beam is higher than 45°. An array of light homogenizing elements is arranged so that each light homogenizing element faces a light incoupling element and so that the deflection angle of at least a fraction of the incident part of the in-coupled light beam incident on each of said homogenizing elements is higher than 45°. The white light source provides a uniform outcoupled white light beam.

Abstract: 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: •grating period (P), separating two adjacent patterns, •grating depth (d) between the highest and the lowest point of the pattern, •incident angle mean value (?) 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.