Abstract: A glazing element, in particular, for facing building facades, having two nes enclosing a gaseous atmospheric intermediate space and having a predetermined layer on at least one pane surface facing the intermediate space. The glazing element is distinguished by the fact that the predetermined layer has a reactive layer applied on one pane and a catalytic layer applied on the reactive layer. The catalytic layer, depending on the composition of the gas atmosphere contained between the panes, activates in the reactive layer. The reaction changes the optical and/or electrical properties of the reactive layer, and varies the composition of the gas atmosphere in the intermediate space, thereby making the electrical and/or optical properties of the reactive layer variable.

Abstract: Gold is useful for infrared polarization-insensitive mirrors on silica. However, gold does not adhere to bare silica. The adherence is enhanced by depositing an optically thin glue layer of Ni-P on a silica surface after sensitization of the surface with SnF.sub.2 and activation with PdCl.sub.2 /HCl. The Ni-P layer is deposited in a thickness sufficient to enhance adherence of gold to the surface of silica but insufficient to act as a barrier to the passage of infrared radiation to or from the gold layer. One measure of the Ni-P thickness is the absorbance of the glue layer of >0.008 at 550 nm (>0.003 at 850 nm) as measured by a spectrophotometer. A 100-150 nm thick gold layer, deposited by e-beam deposition on this adhesion layer, adheres well enough to pass the commonly used "Scotch tape adhesion test". The ability to make gold adhere to silica with very low optical loss is useful in fabrication of lightwave devices which require the use of reflecting surfaces, such as on optical fibers or waveguides.

Abstract: An absorbing anti-reflection coating which can be applied directly to the faceplate of a video display such as a cathode ray tube or a plasma display by physical or chemical vapor deposition comprises at least 3 materials: L, a low retractive index material such as the metal oxide SiO.sub.2 ; H, a high refractive index material such as the metal oxide Nb.sub.2 O.sub.5 ; and M, a metal or metallic alloy or metallic compound layer with a refractive index greater than 0.5 and extinction coefficient less than 5. Preferably the materials are used in the design MHLHL or HMHL. The design and materials provide broadband performance with a low layer count. The single metal layer design permits relatively low values of sheet resistance (high conductivity). Transmittance values are high, typically 70%.+-.5%. Reflectance typically is .ltoreq.0.6%.

Abstract: A mirror for, e.g, an excimer laser is disclosed having high reflectance for a broad band of wavelengths in the ultraviolet range exhibiting excellent adhesion and "laser durability." The mirror comprises a substrate formed from glass or a glass-like material, a dielectric film, and a metallic film, such as aluminum foil, positioned between the dielectric film and the substrate. The dielectric film includes alternating layers of high- and low-refractive index material. These alternating layers reduce the amount of incident light reaching the metallic film so that any damage to the metallic film caused by light is reduced, thereby increasing the laser durability of the mirror. The laser durability is also increased because the durability of the laminated dielectric film is generally superior to that of the metallic film used in prior-art metallic reflector mirrors.

Abstract: Two-layer, thin film coating designs on glass substrates are described which reduce coated surface reflectance while inhibiting the visibility of fingerprints.

Abstract: An optical material having an index of refraction dependent on wavelength of incident radiation is used between the reflectors of an off-normal Fabry-Perot cavity used as an interference filter. External to the cavity, and in the direction of incident radiation, another optical material having an index of refraction dependent on wavelength of radiation is placed. The incident radiation is thus refracted into and within the cavity dependent on its wavelength. By proper choice of the indices of refraction, and other variables, the filter may be designed to exactly match the output spectrum of a line spectrum laser, and to transmit all spectral lines of the laser, but to reflect all other radiation of interest.

Abstract: An optical material having an index of refraction related to wavelength is placed between the reflectors of a Fabry-Perot cavity employed as an interference filter. The cavity is skewed with respect to the optical path of incident radiation such that the material diverts the optical paths of different spectral lines and the filter response more nearly matches the line spectrum.

Abstract: A mirror including a glass substrate, a reflective layer of chromium on the substrate, and a reactively sputtered overcoat of titanium nitride.

Abstract: A coated substrate comprises a transparent substrate, a lower coating on the transparent substrate, a functional layer on the lower coating, and an upper coating on the functional layer. The lower coating has a first layer comprising silicon or a metal, and nitrogen or oxygen, and a second layer comprising zinc oxide and having a thickness of at least 16 nm. The second layer is in contact with the functional layer.

Abstract: Disclosed in this invention is an optical filter to enhance the contrast and brightness of images from a color display. The filter comprises suitable dyes and a polymer matrix, applied in a suitable form on the display unit. Such filters have utility in devices based on CRTs, plasmas and the like.

Abstract: A semiconductor window which is transparent to light in the infrared range and which has good electrical conductivity is formed of a prefabricated semiconductor sheet bonded to a substrate material by optical contact. The sheet is a substantially uniformly doped wafer sufficiently thin that inherent absorption bands do not affect transmission. The sheet is contact bonded to the surface of an undoped transparent substrate without diffusion, growth or deposition on the surface. Windows having particular optical band pass characteristics are formed utilizing a zinc selenide substrate and a gallium arsenide sheet.

Abstract: A color filter plate includes a continuously-variable dichroic filter coating constituting a variable band-pass or variable band-reject filter having a spatially-modulated variable-density pattern formed in the coating, and provides continuously-variable hue and saturation characteristics along separate gradient axes. A color filter assembly includes a variable band-pass and a variable band-reject filter mounted in a co-planar arrangement, providing a continuous range of color filtration for spectral and non-spectral colors. A color filter mechanism includes a color filter assembly having either a rectangular arrangement or a circular arrangement of co-planar, continuously-variable band-pass and band-reject filters mounted in a motorized carriage. One mechanism provides two-axis translation of the rectangular color filter assembly while another mechanism provides translation and rotation of the circular color filter assembly.

Abstract: An optical thin film for an optical element is disclosed, which includes at least one layer containing at least one compound selected from the group consisting of MoO.sub.3 and WO.sub.3. A material for use in evaporation coating to prepare a thin film includes a mixture of at least one compound selected from the group consisting of MoO.sub.3 and WO.sub.3 and another dielectric. A further optical thin film includes a substrate and superimposed thereon are alternate layers. One such alternative layer having a high refractive index, and composed of a material containing at least one compound selected from the group consisting of MoO.sub.3 and WO.sub.3. Another of such alternative layers having a low refractive index, and composed of SiO.sub.2. Another thin film includes a substrate and, superimposed thereon, at least one dielectric layer. The at least one dielectric layer being at least one layer containing at least one compound selected from the group consisting of MoO.sub.3 and WO.sub.

Abstract: An anti-reflective film construction contains an optically transparent polymeric film having a textured surface and an optically transparent adhesive, the film construction configured to exhibit light transmission of greater than about 70 percent and 60.degree. gloss measurement of between about 15 and 100. Methods of producing such film constructions and methods of reducing reflection from a surface are also described.

Abstract: A beam splitter formed by laminating a plurality of optical films on a glass substrate having a refractive index of 1.51.+-.0.10. The optical films are first, second, third, fourth, and fifth layers laminated in this order from the glass substrate. The first layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.05-0.15; the second layer has a refractive index of 1.68.+-.0.10 and an optical film thickness of 0.01-0.10; the third layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.50-0.60; the fourth layer has a refractive index of 2.23.+-.0.10 and an optical film thickness of 0.25-0.35; and the fifth layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.25-0.35. The optical film thickness means a relative value represented by n.times.d/.lambda. where n denotes a refractive index; d denotes an actual film thickness, and .lambda. denotes a wavelength deciding the center of a wavelength band.

Abstract: An antireflectance coating is disclosed comprising a first graded layer wherein the composition is varied throughout the thickness of the layer such that the refractive index of the graded layer varies from a low refractive index approximately matching the refractive index of the substrate at the interface of the graded layer and the substrate to a higher refractive index at the surface of the graded layer opposite the interface with the substrate, and a second substantially homogeneous layer of a composition selected to have a refractive index which is approximately the square root of the product of the higher refractive index of the graded layer and the refractive index of the incident medium at the surface of the second layer opposite the interface of the second layer with the graded layer, having an optical thickness of approximately at least one quarter of a selected design wavelength.

Abstract: A very low reflectance optical coating comprising alternating layers of materials such as chromium oxide and chromium, silicon oxide and silicon, titanium oxide and titanium, and tantalum oxide and tantalum is suitable for use as a black shadow mask in liquid crystal displays, among various applications. Certain designs such as silicon oxide/silicon benefit from a transmission-decreasing overcoat of material such as molybdenum, germanium or titanium.

Abstract: A filter is constructed consisting of an optical cavity having at least one element which is a square mesh of highly-conductive metal on a transparent substrate. The mesh openings are defined by relatively narrow conductors of the metal. The mesh feature size, as determined by the sum of the conductor width and square size length, is below the diffraction limit for incoming radiation of interest.

Abstract: A mirror assembly including a semitransparent mirror which passes about 1% to about 8% of a broad band of visible light, and which reflects about 35% to about 58% of a broad band of visible light. A light assembly is positioned adjacent to the semitransparent mirror and emits visible light which is passed by the semitransparent mirror. The luminous intensity of the mirror assembly being about 2 to about 20 candelas.

Abstract: An optical multiplexing device spatially disburses collimated light from a fiber optic waveguide into individual wavelength bands, or multiplexes such individual wavelength bands to a common fiber optic waveguide or other destination. The optical multiplexing device has application for dense channel wavelength division multiplexing (WDM) systems for fiber optic telecommunications, as well as compact optical instrument design. Multiple wavelength light traveling in a fiber optic waveguide is separated into multiple narrow spectral bands directed to individual fiber optic carriers or detectors. An optical block has an optical port for passing the aforesaid multiple wavelength collimated light, and multiple ports arrayed in spaced relation to each other along a multiport surface of the optical block. A continuous, variable thickness, multi-cavity interference filter extends on the multiport surface of the optical block over the aforesaid multiple ports.

Abstract: A thin-film color-selective beam splitter and the method of fabricating the same are disclosed. The method includes the steps of: (i) forming a main prism by a pre-selected material, and deciding a first base angle and a second base angle according to the substance and coating characteristics of the pre-selected material; (ii) coating a first multilayer film and a second multilayer film on two slopes of the main prism, in which tilt angles for coating the first multilayer film and the second multilayer film and tilt angles of light entering and emerging the main prism are different, so that spectra of the first multilayer film and the second multilayer film are different, and the first multilayer film can be a red reflective film and the second multilayer film can be a blue reflective film; and (iii) using the pre-selected material to form interface prisms, and adhering the interface prisms to the main prism, so that light can perpendicularly enter and emerge from surfaces of the prism.

Abstract: An improved way to impart antireflection properties to light transmissive substrates and, at the same time, achieve a durable surface and electrical conductivity is disclosed. A stack of at least two sputter-deposited light transmissive inorganic layers, one of which being electrically conductive and having a high index of refraction with the one above it (relative to the substrate being antireflected) having a low index of refraction, in combination with a thin lubricating overlayer comprising a solvent-soluble lubricant such as a solvent-soluble fluoropolymer can achieve this desired combination of properties.

Abstract: A glass article having a solar control coating is disclosed for use in producing heat reducing glass for architectural windows. The coated article includes a glass substrate, an iridescence-suppressing interlayer deposited on and adhering to the surface of the glass substrate. At least a first transparent coating deposited on and adhering to the surface of the iridescence-suppressing coating and at least a second transparent coating deposited on and adhering to the surface of the first transparent coating. The first transparent coating and the second transparent coating have a difference in refractive indices in the near infrared region greater than a difference in the refractive indices in the visible region. The use of the article in architectural glazing results in a glazing that rejects solar energy in the near infrared region while permitting the transmittance of a high degree of visible light.

Abstract: A polarization insensitive, multilayer planar reflection filter is provided having (I) strong sidelobe suppression, preferably with sidelobe suppression levels in the range of -30 dB to -50 dB, and (ii) minimum width of the filtered bandwidth for the specified sidelobe suppression level. The multilayer planar reflection filter is provided by a multilayer stack by specifying the manner in which the thickness of the individual dielectric layers are to be varied throughout the stack. The resulting universal design formula specifies these layer values for a stack with an arbitrary number of layers, dielectric constant, incident angle, and wavelength. In particular, the layer thickness values of the alternating layer d.sub.1 (j) in refractive index n.sub.0, and d.sub.2 (j) in refractive index n.sub.0 +.DELTA.n, vary with each period j and are determined to provide a specified central wavelength, sidelobe suppression and minimum filtered band width.

Abstract: A window includes a first layer of a dielectric first material that transmits radiation in the visible or the infrared, and a second layer positioned adjacent to the first layer. The window is positioned so that the radiation is incident upon the first layer. The second layer is formed of a dielectric or semiconductor second material that transmits radiation in the same wavelength range as the first material. A first electrical conductor lies between the first layer and the second layer. A second electrical conductor lies on at least one of an exterior surface of the first layer remote from the second layer and an interior surface of the second layer remote from the first layer. Where the first and second materials are selected to transmit in the infrared, the first and second electrical conductors are grids. Where the first and second materials are selected to transmit light in the visible, the first and second electrical conductors are continuous layers.

Abstract: A coated substrate is covered with a barrier or base coating having spaced apart transparent electrodes deposited thereon. The base coating and electrodes are arranged such that the electrodes and the base coating together and the base coating alone have at least matching photopic reflectivity in a selected liquid, and preferably have matching spectral response in the selected liquid, over a wavelength range between about 470 and 650 nm.

Abstract: This invention is a product comprising a transparent substrate of the glass substrate type (1), coated with at least one thin film (4) based upon an oxide comprising silicon, aluminum and at least one third element M facilitating the formation of a homogeneous mixed oxide structure of silicon and aluminum. The invention also concerns a method of manufacturing coated glass, especially by a gas phase pyrolysis technique, and its applications.

Abstract: A beam splitter formed by laminating a plurality of optical films on a glass substrate having a refractive index of 1.51.+-.0.10. The optical films are first, second, third, fourth, and fifth layers laminated in this order from the glass substrate. The first layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.05-0.15; the second layer has a refractive index of 1.68.+-.0.10 and an optical film thickness of 0.01-0.10; the third layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.50-0.60; the fourth layer has a refractive index of 2.23.+-.0.10 and an optical film thickness of 0.25-0.35; and the fifth layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.25-0.35. The optical film thickness means a relative value represented by n.times.d/.lambda. where n denotes a refractive index; d denotes an actual film thickness, and .lambda. denotes a wavelength deciding the center of a wavelength band.

Abstract: The durability of thin metal coatings and particularly substantially transparent copper and silver plus noble metal coatings and their ability to withstand corrosive environments is improved by overcoating the metal layers with a double coating of dielectric. The first coating is made up of dielectric based on indium and/or zinc. The second coating is made up of dielectric based on indium and tin. These overcoatings are more effective than a single coating based on one metal or a single coating based upon the two metals.

Abstract: A narrow-band antireflective coating is comprised of a multilayer dielectric film formed on a dielectric substrate. The antireflective coating is initially formed so that its outer layer has a thickness greater than the thickness required for antireflection. The reflectivity is monitored while outer layer is reduced in thickness to reduce the thickness of the outer layer to reduce the reflectivity.

Abstract: An environmentally stable silver mirror having very high reflection values over a large spectral range comprises a silver layer disposed on a substrate, which is covered by a zinc sulfide layer. So that the sulphur being set free during the application or during the vaporization of the zinc sulfide to be applied, does not attack the silver, at least one barrier or intermediate layer is placed between the silver layer and the zinc sulfide layer.

Abstract: A glass article used for producing a coated, solar control glass for architectural windows. The coated article includes a glass substrate, a coating of titanium dioxide deposited on and adhering to the surface of the glass substrate, a coating of silicon dioxide deposited on and adhering to the surface of the coating of the titanium dioxide, a second coating of titanium dioxide deposited on and adhering to the surface of the coating of the silicon dioxide, and an outer coating of conductive tin oxide deposited on and adhering to the surface of the coating of titanium dioxide. A specific coating stack on the glass substrate provides a neutral colored article having a high visible light transmittance, a reduced solar energy transmittance, a low emittance, and a high total solar reflectance. The use of the article in architectural glazings results in a glazing that reflects solar energy in the summer and provides a low U value for the winter.

Abstract: The present invention relates to multilayered filter films, and in particular, a multilayered filter film not having a substrate and a method for making the same. The method for making the multilayered filter film not having a substrate includes a step for forming a filter frame layer having a window on the substrate, a step for forming a multilayered film on the substrate inside the window and on the filter frame layer, and a step for removing the substrate from the filter frame layer and the multilayered film.

Abstract: A photonic signal is applied to a photonic bandgap structure having a photonic band edge transmission resonance at the frequency of the photonic signal and having a photonic band edge transmission resonance bandwidth which is at least as wide as the bandwidth of the photonic signal. When a photonic band edge transmission resonance is matched to the photonic signal which is being transmitted, a controllable delay is imparted to the photonic signal without significantly altering the photonic signal itself.

Abstract: A method of producing mirrors comprising depositing onto a ribbon of hot glass during the production process a coating comprising at least one pyrolytic reflecting layer and at least one color modifying layer whereby the mirrors exhibit color in reflectance and have a visible light reflection of at least 35% and less than 70%. There is also a provided a mirror having such a coating.

Abstract: A elemental mirror for vehicles having a luminous reflectance of at least about 30% includes a substrate coated with a thin layer of elemental semiconductor having an index of refraction of at least 3 and an optical thickness of at least about 275 angstroms. Preferably, the elemental semiconductor coating is sputter coated silicon or germanium and a light absorbing coating is included therebehind. The mirror is spectrally nonselective with elemental semiconductor optical thicknesses of about 275 to 2400 angstroms on the front substrate surface. Spectrally selective mirrors are provided by adding an interference coating to the elemental semiconductor layer coating, preferably of a dielectric such as silicon dioxide or silicon nitride, on either the front or rear substrate surface, or by using a thicker, single elemental semiconductor layer. Instead of an absorbing coating behind the mirror, additional elemental semiconductor and dielectric thin layers may be included to reduce secondary reflections.

Abstract: An aspheric optical element formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin (.about.100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application.

Abstract: An optical pellicle and method of forming an optical pellicle. The pellicle includes a membrane and an anti-reflective coating covering at least one of the membrane surfaces. The membrane has a wavelength transmission pattern with consecutive first and second maximum transmission peaks where the first maximum transmssion peak corresponds to a wavelength of 365 nm and the second maximum transmission peak corresponds to a wavelength of 436 nm. The pellicle transits at least 99 percent of light striking said pellicle having a wavelength of about 361 nm to 369 nm and at least 99 percent of light striking said pellicle having a wavelength of about 430 nm to 442 nm. In one embodiment, the anti-reflective coating includes at least one intermediate layer having a refractive index less than the refractive index of the membrane, and an outer layer having a refractive index less than the refractive index of the intermediate layer.

Abstract: An optical filter arrangement comprises at least two optical filter elements including a transparent substrate and an optical coating typically comprising at least two overlying optical thin films. The coating defines a first patterned area and a second surround area bordering the first area. The first area has substantially the same optical transmittance characteristics as the second area and different optical reflectance characteristics over at least a portion of the visible spectrum. The distinction between the first area and the second area is visually perceptible when viewed from one side of the optical filter arrangement and is substantially visually imperceptible when viewed from the opposite side of the optical filter arrangement. As a result, a coloured pattern or logo is only visible when viewed from one side of the filter arrangement. The invention extends to a method of forming such an arrangement.

Abstract: The present invention relates to electrically-conductive, absorbing, contrast-enhancing antireflection coatings having excellent optical properties characterized by, specifically, a large bandwidth ratio, i.e., a ratio indicative of the range of wavelengths for which the reflectance value is less than 0.6%, and a small brightness value for the visible wavelengths. It has been surprisingly discovered that a simple, two-layer substrate coating consisting of only a first thin layer of a transparent material having a low refractive index and a second very thin layer of an absorbing, electrically conductive, transition metal oxynitride material provides high performance, electrically conductive, contrast-enhancing antireflection coatings having small brightness values and large bandwidth ratios. The present invention provides antireflection coatings having brightness values less than or equal to about 0.22, and preferably less than or equal to about 0.15.

Abstract: A method and apparatus are provided for emitting a laser like monochromatic narrow beam of light at a selected wavelength from a heated emitter member having a plurality of parallel layers while reducing emission at other wavelengths of light. The parallel layers are overlaid with each other. Each of the parallel layers extends transversely for a particular width. A heat source stimulates the emitter member to emit photons, which are determined by the composition of materials within the emitter member. The emitter member emits monochromatic light at a selected wavelength in response to the photon emissions. The selected wavelength of the monochromatic light is determined by the width of the layers of the emitter member. Light at other wavelengths does not transmit through and their emissivity also decreases.

Abstract: An optical filter includes a dielectric layer formed within a resonant optical cavity, with the dielectric layer having formed therein a sub-wavelength periodic structure to define, at least in part, a wavelength for transmission of light through the resonant optical cavity. The sub-wavelength periodic structure can be formed either by removing material from the dielectric layer (e.g. by etching through an electron-beam defined mask), or by altering the composition of the layer (e.g. by ion implantation). Different portions of the dielectric layer can be patterned to form one or more optical interference filter elements having different light transmission wavelengths so that the optical filter can filter incident light according to wavelength and/or polarization. For some embodiments, the optical filter can include a detector element in optical alignment with each optical interference filter element to quantify or measure the filtered light for analysis thereof.

Abstract: A spectral imager or spectrophotometer-type optoelectronic camera including an optical system, a CCD-type set of photosensitive elements (3) at the focus of the optical system, a transparent protective window (5) arranged in front of the sensitive face (4) of the set of photosensitive elements (3), and a spectral disperser (1) allowing spectral analysis of the scene observed by the camera. The sensitive face (4) of the set of photosensitive elements (3) that points toward the protective window is coated with a monolayer or multilayer coating of anti-reflection material (9) whose thickness (e) varies continuously as a function of the wavelength of the light received by the sensitive face, parallel to the dispersion axis of the disperser (A).

Abstract: A novel design for producing bandpass filters with essentially square shapes with little or no ripple in the passband zone. Filters are of the all-dielectric type that consist of multiple cavities of bandpasses with the first and last cavities consisting of four less layers than the inner cavities. The inner cavities all have the same number of layers. All of the cavities are separated from each other by quarter wave thick layers of low index material. Layers of low index material may be added between the filter and the entrance and exit mediums. Multiple half-waves are added to the outer cavity quarter-wave stacks in particular and also may be added to some of the inner cavity stacks, These sharpen the transition from low transmission to high transmission without unduly adding ripple to the high transmission zone. The thickness of the first few layers and last few layers may be altered to enhance the transmission of the filter by matching the index structure of the passband to the adjacent mediums.

Abstract: A thin-film-type ND filter which attenuates the amount of light transmission is formed on a transparent substrate by using two or more types of metallic oxide having a refractive index n and an attenuation coefficient k which are in the range of 1.0 to 3.0 in the wavelength region of the visible region, making it possible to obtain flat transmittance characteristics.

Abstract: A multi-color optical display system (10) employs a multi-powered reflective combiner (20) that together with a monochromatic or partly color-corrected relay lens (16) longitudinally corrects a multi-colored image. The combiner typically includes two surfaces (82, 90) of different optical powers with a reflective coating (106, 108) on each of the surfaces. The coatings are chosen to each reflect a specific wavelength range of colored light used in the system and to transmit all other wavelengths. The curvature of each surface is dictated by the aberrations in the color image created by the relay lens. Specifically, each surface is positioned so that its focus (86, 94) coincides with the focal point (58, 60) of the corresponding color component in an intermediate image (18) created by the relay lens so that the final virtual image (22) reflected by the combiner is longitudinally color corrected.

Abstract: An optical interference coating for reflecting infrared radiation and transmitting visible radiation. The coating includes three spectrally adjacent, multiperiod dielectric stacks. Two of the dielectric stacks are shortwave pass stacks. The third dielectric stack contains seven alternating layers of high and low refractive index materials.

Abstract: An optical filter is formed from at least two gratings (102,103) located in a waveguide region (104) of a` semiconductor optical device (101). Each grating has a multiple peak optical passband. The gratings are spaced apart in the waveguide region and form an optical cavity having a comb-filter characteristic. The gratings may be located in the active region of an optical gain element and in a preferred example are superstructure gratings (SSGs). A number of filters may be joined together in series.

Abstract: The invention relates to an optical component consisting of transparent thin layers of differing thickness and refractive indices. Such optical components are used, for example, as interference filters and mirrors. Optical components made of layers with gradually changing refractive indices are also known as waveguides of anti-reflective coatings. The invention achieves the aim of using, instead of layers of ordinary materials, another material by means of a component in which the layers consist of porous silicon. The special advantages of porous silicon as a coating material arises not only from the ease and economy of manufacture, but also in the facility for obtaining gradual refractive index transitions. It is therefore very easily possible to make waveguides on a silicon chip.

Abstract: A sunglass has a multilayer coating on its concave (rear) surface that comprises a absorbing layer and at least one composite layer for reducing transmittance of UV radiation. Reflection of visible light at the concave surface is minimized.