Abstract: This invention relates to a new optical geometry for using a linear variable filter as an optical spectral filter. An elliptical beam geometry with the minor beam axis oriented along the linearly varying axis of the filter is used. The beam is incident at a slight angle relative to the long axis of the beam. Ultimately this geometry produces a filter which has minimum spectral broadening from both angular and beam extent effects. Furthermore, this geometry results in low back reflectance and higher input beam power damage thresholds. The optical filter includes means for tuning a wavelength response of the filter. Further, the optical filter can afford Add/Drop functionality by providing optical circulators at the input and output ports.

Abstract: A multi-wavelength etalon comprises at least two regions with different indices of refraction. The change in refractive index alters the wavelengths of incident light, and thus the number of wavelengths between the reflective surfaces of the etalon, and therefore the etalon's transmission characteristics. By selecting specific indices of refraction, an etalon can be provided which produces peaks and troughs at preselected wavelengths in each region. The transition between two adjacent regions with different indices of refraction can be graded to reduce optical interference which may result from an abrupt transition.

Abstract: A Fabry-Perot filter comprises at least two mirror structures defining a resonant cavity. This filter is tunable by modulating an optical distance between the mirror structures. To accommodate a wide bandwidth of operation or accommodate two spectral bands, the mirror structures are made from two stacked, single-band mirrors. In more detail, the mirror structures comprise a substrate; a first mirror is deposited on the substrate, with an index matching coating between the substrate and the first mirror. The second mirror is stacked on the first mirror. The mirrors are symmetric relative to each other, such that the index of a first mirror in the second spectral band has an effective index of about one. In contrast, the second mirror has an effective index of about one in the first spectral band.

Abstract: An improved interferometric modulator permits the reduction in size of optical transmitters. In one embodiment, the optical modulator includes amplifiers or attentuators as phase modulators. In another embodiment, two outputs from a combiner are fed to the modulator, thus avoiding the requirement for an input splitter in the modulator. Light passing through the modulator may be both phase-shifted and amplified or attenuated by optical regulator sections located in the modulator. In another embodiment, the transmitter is included as a multiple-wavelength optical communications source, where individual current sources are provided to actuate a number of light sources feeding into the combiner, a processor controls the operation of each light source, and a modulator driver receives a data input signal to be encoded on the output of the source. By combining a number of modulators, a gray scale modulator may be fabricated for producing a gray scale output, rather than a conventional binary level output.

Abstract: A multilayer optical interference filter having a multiplicity of optical cavities separated by a dielectric reflector stacks to achieve either a very narrow passband region or sharp transition between the passband and reflective region is substantially free of stress to preserve the desired optical performance upon fabrication into miniature discrete filter elements. The substantial stress reduction is achieved by removing the filter from the substrate used in the deposition process in a controlled manner to preserve the structural integrity of the resulting free standing multilayer film structure. The structure can be further bonded or attached to other optical components to suppress a thermal shift in center wavelength without reintroducing stress or interposing a massive substrate in the optical path through the filter.

Abstract: Various configurations of a virtually imaged phased array (VIPA) generator in combination with a mirror to compensate for chromatic dispersion. A VIPA generator produces a light traveling from the VIPA generator. In some embodiments, a variable curvature mirror is positioned to reflect the light back to the VIPA generator. A rotation axis around which the mirror is rotated and a translation path for the rotation axis are provided, to change the curvature of the mirror where the output light is reflected. In other embodiments, a plurality of mirrors have different surface curvatures. A holder has a rotation axis and holds the plurality of mirrors equidistantly from the rotation axis. The holder is rotatable around the rotation axis to bring a different, respective mirror in position to reflect light produced by a VIPA generator back to the VIPA generator. In other embodiments, a rotating mirror is rotatable about a rotation axis to reflect light produced by a VIPA generator to a respective fixed mirror.

Abstract: A coupler-based programmable phase logic device operates using coherent optical or microwave signals. The device is composed of a mixing stage and a logic stage and utilizes 3-port and 4-port couplers, such as integrated optic non-3dB Y-branches and integrated optic directional couplers. The device receives two coherent data input signals and three coherent control input signals and produces a coherent phase modulated data output signal. The data input signals are externally phase modulated to have one of two relative phase values, as in the binary phase shift keying (BPSK) method The data output signal is a phase modulated signal having one of the two relative phase values that is related to the phase values of the data input signals by a Boolean logic function, such as OR, AND, NAND, or NOR. The control input signals determine the logic function performed by the device and can be changed dynamically for dynamic device operation.

Abstract: An optical apparatus for producing chromatic dispersion. The apparatus includes a virtually imaged phased array (VIPA) generator, a mirror and a lens. The VIPA generator receives an input light at a respective wavelength and produces a corresponding collimated output light traveling from the VIPA generator in a direction determined by the wavelength of the input light, the output light thereby being spatially distinguishable from an output light produced for an input light at a different wavelength. The mirror has a cone shape, or a modified cone shape. The lens focuses the output light traveling from the VIPA generator onto the mirror so that the mirror reflects the output light. The reflected light is directed by the lens back to the VIPA generator. In this manner, the apparatus provides chromatic dispersion to the input light.

Abstract: A transparent iridescent thermoplastic resinous laminate film having at least 10 very thin layers of substantially uniform thickness, said layers being generally parallel, the contiguous adjacent layers being of different transparent thermoplastic resinous materials of which one is a naphthalate-based polyester or copolyester resin, the contiguous adjacent layers differing in refractive index by at least about 0.03.

Abstract: The tunable optical filter comprises a Fabry-Perot cavity and a controlled-index device. The controlled-index device is located in the Fabry-Perot cavity and has a refractive index responsive to a control signal. The Fabry-Perot cavity has at least one resonant optical frequency that depends on the refractive index of the controlled-index device. The Fabry-Perot cavity has a maximum transmissivity for light having a frequency equal to its resonant optical frequency, and attenuates light whose frequency differs from the resonant optical frequency. Thus, the control signal controls the frequency of the light transmitted by the tunable optical filter.

Abstract: An apparatus for processing an optical signal includes a tunable optical element and a reflective element. The tunable optical element receives an input signal at an incidence angle and separates the input signal into a first beam having a first optical path length and a second beam having a second optical path length. The difference between the first optical path length and the second optical path length is based at least in part upon the incidence angle of the input signal. The reflective element reflects the first beam and the second beam such that the first beam interferes with the second beam to produce a first output signal and a second output signal. The first output signal comprises a first subset of wavelength channels from the input signal and the second output signal comprises a second subset of wavelength channels from the input signal.

Abstract: A tunable optical notch filter employing a Fabry-Perot etalon has a first partially reflective mirror and a second mirror with variable effective reflectivity. Both the gap of the etalon and the effective reflectivity of the second mirror can be controlled, e.g. by TAB actuators, enabling a control of the central wavelength and the depth (loss) of the notch of the spectral response of the filter.

Abstract: A method and apparatus for interference lithography utilize a fiber having a cladding region with axially formed holes surrounding a core region. The fiber emits an optical signal to perform interference lithography. A number of alternative variations in the size and arrangement of axially formed holes produces fibers having characteristics particularly adapted for receiving, communicating, and emitting optical signals for interference lithography.

Abstract: For lithographically producing the smallest structures at less than the exposure wavelengths in semiconductor fabrication, a double exposure is carried out using a thick phase mask and a trimming mask, the trimming mask further structures the phase-contrast lines produced by the phase mask. Besides transparent or opaque regions, the trimming mask also has phase-shifting regions. These surround transparent regions of the trimming mask through which the phase-contrast lines produced by the first mask are locally re-exposed, that is to say interrupted. The intensity profile of successive line sections is especially rich in contrast through the addition of the phase-shifting partially transparent regions on the second mask; the distances between the line sections can be reduced. The trimming mask, otherwise used only for larger structures, is therefore suitable for the configuration of the finest dimensionally critical structures.

Abstract: A multi-wavelength etalon comprises at least two regions with different indices of refraction. The change in refractive index alters the wavelengths of incident light, and thus the number of wavelengths between the reflective surfaces of the etalon, and therefore the etalon's transmission characteristics. By selecting specific indices of refraction, an etalon can be provided which produces peaks and troughs at preselected wavelengths in each region. The transition between two adjacent regions with different indices of refraction can be graded to reduce optical interference which may result from an abrupt transition.

Abstract: An optical waveguide format tuneable optical filter is formed using Bragg grating reflectors to define one or more optical cavities of a Fabry Pérot etalon, the or each cavity of the etalon including one or more slots containing a controllable refractive index medium, for instance a silicone gel whose index is regulated by Joule heating, or a polymer dispersed liquid crystal whose index is electric field regulated. Strong coupling coefficient (˜ a few tens mm−1) gratings may be made using lithography to form linear arrays of buried high index inclusions extending along the waveguide core axis.

Abstract: A super high resolution optical resonator comprising a Fabry-Perot cavity and an intracavity diffraction grating which is operated in a non-zero diffraction order. The diffraction grating is of transmission or reflection type, blazed, single or multiple order. The resonant cavity can comprise two independent mirrors, multiple mirrors, or an optical resonator based on an optical fiber and one or more intracavity diffraction gratings operated in non-zero diffraction order inserted between the two or more mirrors or portions of the fiber, respectively.

Abstract: An electromagnetic wavelength filter that allows the transmission of electromagnetic energy within a narrow range of wavelengths while reflecting incident electromagnetic energy at other wavelengths. The filter includes at least one cavity region; and at least two reflectors surrounding the at least one cavity region, at least one of the reflectors being an omni-directional reflector. The omni-directional reflector includes a structure with a surface and an index of refraction variation perpendicular to the surface, and the omni-directional reflector is specifically configured to exhibit high omni-directional reflection for a predetermined range of frequencies of incident electromagnetic energy for any angle of incidence and any polarization.

Abstract: An optical element having wavelength selectivity, which is easy to manufacture and reduces the manufacturing cost. The optical element comprises a lens array (12) having one end face and a plurality of lenses (L1-L8) arranged on the one end face, and a multi-layered film filter (13) formed on the one end face (14) of the lens array. The multi-layered film filter includes high refractive-index dielectric layers and low refractive-index dielectric layers laminated alternately and its film thickness continuously changes in accordance with positions of the individual lenses. The center wavelength of transmitted light from the multi-layered film filter varies in accordance with the position of the lens array. In a case where mixed light enters the multi-layered film filter from the individual lenses, the mixed light is demultiplexed into lights of different center wavelengths by the multi-layered film filter that has difference thicknesses.

Abstract: The present invention provides a manufacturing method capable of obtaining minute structures. In order to achieve this, as shown in FIG. 1, a process target material (108) is exposed and the shape thereof is changed by relatively shifting a laser beam or electronic beam (101) against such process target material (108) and simultaneously repeating irradiation in an intermittent manner. Here, a plurality of minute convex or concave shapes are formed on the process target material (108) by employing a branching element (103) for branching a single beam (108) into a plurality of beams (106, 107); a parallel element (104) for converting said plurality of beams into beams which respectively advance in parallel; and a condensing element (105) for condensing the plurality of beams to the process target material (108) and generating a plurality of minute spots thereon.

Abstract: A method of adjusting a first spot size for a first color component (74) of a multiple color co-axial laser beam (70) that comprises, focusing the multiple color co-axial laser beam (70). Filtering the multiple color co-axial laser beam (70) with a filter (50) to adjust the first spot size. The filter (50) is opaque to the first color component (74) in an annular region (62) and transparent to the first color component (74) in a center region (60) of the multiple color co-axial laser beam (70). The filter (50) is transparent to a second color component (76) of the multiple color co-axial laser beam (70) in both the center region (60) and the annular region (62).

Abstract: A thermally stable etalon filter includes a pair of spaced apart mirrors defining a Fabry-Perot cavity and an optical medium disposed in the cavity. The optical medium is comprised two optically transparent materials, one having a coefficient of thermal expansion that is countervailing to the coefficient of thermal change of refractive index of the other. The thicknesses of the two materials are selected so that the thermal expansion of the optical medium offsets the thermal change in the refractive index, resulting in an etalon filter that is substantially immune to variations caused by temperature. In a further embodiment, the optical medium is comprised of a single material having having a coefficient of thermal expansion and a coefficient of thermal change in refractive index that are functionally opposite. These material properties lead to a beam insertion angle at which the beam refraction is not affected by temperature fluctuations in the material.

Abstract: A wavelength locker for use with tunable optical devices, such as tunable lasers, detectors, or wavelength selection filters is described. The invention enables the determination of an optical wavelength or waveband position of a tunable device. Embodiments of the invention supply a reference wavelength which may be used to tune the tunable device to a specified wavelength or waveband. The invention enables the tunable device to be locked to a desired wavelength. The invention enables discrete and continuously tunable optical wavelength determination and locking across a waveband. Applications for the invention include utilization in optical networks. For instance, the invention may be utilized to reference, tune, and lock an incoming signal at the receiving end of an optical network link. In particular, the invention may be used in tunable laser sources, tunable detectors, or tunable optical signal filters as used in optical fiber communications and DWDM applications.

Abstract: Rays of light having respective wavelengths angular-dispersed and output from a VIPA plate are collected by a lens, and diffracted by a grating pair which is an optical path shift generation unit and optical path shift amount variation unit, and have a shift in a path of rays having different wavelengths. When the rays are reflected by a dispersion leveling three-dimensional mirror and input into the VIPA plate again, they are received by portions having different dispersion compensation amount of the three-dimensional mirror, thereby realizing different amounts of wavelength dispersion for respective wavelengths, and independently adjusting an amount of wavelength dispersion of the entire wavelengths of the WDM rays and the wavelength dispersion slope.

Abstract: A one-way imaging optical film is provided by a transparent polymer substrate bearing a first coating defining an image area and a second coating defining a background or surround area. In the visible light spectrum, the two coatings have very similar light transmittance characteristics and very similar reverse reflectance characteristics, but different reflectance characteristics such that when the film is viewed from the coated side the image area is visually distinct from the surround area, and when the film is viewed from the substrate side, the film is transparent and the image virtually non-discernible. The film has a visible light transmittance of at least about 25 percent for use especially as an architectural and vehicle window film.

Abstract: An optical apparatus for producing chromatic dispersion. The apparatus includes a virtually imaged phased array (VIPA) generator, a mirror and a lens. The VIPA generator receives an input light at a respective wavelength and produces a corresponding collimated output light traveling from the VIPA generator in a direction determined by the wavelength of the input light, the output light thereby being spatially distinguishable from an output light produced for an input light at a different wavelength. The mirror has a cone shape, or a modified cone shape. The lens focuses the output light traveling from the VIPA generator onto the mirror so that the mirror reflects the output light. The reflected light is directed by the lens back to the VIPA generator. In this manner, the apparatus provides chromatic dispersion to the input light.

Abstract: A method of adjusting a first spot size for a first color component (74) of a multiple color co-axial laser beam (70) that comprises, focusing the multiple color co-axial laser beam (70). Filtering the multiple color co-axial laser beam (70) with a filter (50) to adjust the first spot size. The filter (50) is opaque to the first color component (74) in an annular region (62) and transparent to the first color component (74) in a center region (60) of the multiple color co-axial laser beam (70). The filter (50) is transparent to a second color component (76) of the multiple color co-axial laser beam (70) in both the center region (60) and the annular region (62).

Abstract: Various configurations of a virtually imaged phased array (VIPA) generator in combination with a mirror to compensate for chromatic dispersion. A VIPA generator produces a light traveling from the VIPA generator. In some embodiments, a variable curvature mirror is positioned to reflect the light back to the VIPA generator. A rotation axis around which the mirror is rotated and a translation path for the rotation axis are provided, to change the curvature of the mirror where the output light is reflected. In other embodiments, a plurality of mirrors have different surface curvatures. A holder has a rotation axis and holds the plurality of mirrors equidistantly from the rotation axis. The holder is rotatable around the rotation axis to bring a different, respective mirror in position to reflect light produced by a VIPA generator back to the VIPA generator. In other embodiments, a rotating mirror is rotatable about a rotation axis to reflect light produced by a VIPA generator to a respective fixed mirror.

Abstract: An element includes a periodic structure formed on a surface of a base member and having a period smaller than a wavelength of incident light and an additional layer added on the periodic structure. The additional layer has a refractive index lower than that of a material for the periodic structure formed on the surface of the base member.

Abstract: A Fabry-Perot etalon comprises two faces having a reflecting film. A beam is transmitted through the Fabry-Perot etalon and split into two. One face is inclined to the other so that each of the two beams will relatively shift in a phase difference of &pgr;/2. The Fabry-Perot etalon is used as a wavelength discrimination unit. The beam transmitted through the Fabry-Perot etalon is branched off by a knife-edged mirror and reflected therein. The branched beams are received by first and second PDs, respectively, and signals which depend on wavelength are detected.

Abstract: Optical assembly for controlling or limiting undesirable photon entrance, reflection, departure, or appearance. A material opaque to unwanted photons can be applied to an optical assembly that would otherwise allow penetration of the unwanted photons. For example, a filter can be applied to a waveguide member. A first face surface of the filter faces toward an end of the waveguide member and a second face surface of the filter faces away from that member end. A mask adheres to one of the filter surfaces. The mask is substantially opaque in at least some selected spectral region to impact the extent to which photons in that spectral region can pass through the filter and to the waveguide member.

Abstract: A diffractive optical element has a diffraction grating formed by periodic depressions and projections on the surface of a substrate and a dielectric multilayer film on the diffraction grating. The materials of the respective layers of the film are chosen such that the depth of the depressions is an integral multiple of the sum of the thickness of the layers in one period of the film. As a result, individual layers of the film are continuous across multiple depressions and projections, to provide improved first-order reflectance.

Abstract: A tunable optical filter is based on a conventional thin film optical filter. The thickness of the thin film optical filter determines the optical properties of the filter, specifically the pass band. The thin film optical filter is arranged within a hole extending through a layer of piezoelectric material such that the periphery of the thin film optical filter is secured to the periphery of the hole. Electrodes are provided on opposite surfaces of the piezoelectric layer such that different voltage levels can be applied. The resulting deformation of the piezoelectric layer causes a difference in the thickness of the thin film optical filter thereby permitting tuning of the optical filter.

Abstract: The present invention provides an improved tunable chromatic dispersion compensator. The compensator includes: a virtually imaged phased array (VIPA); at least one reflector optically coupled to the VIPA; a mirror optically coupled to the at least one reflector; and a movable reflector holder coupled to the at least one reflector, where the movable reflector holder moves the at least one reflector such that a length of a beam path between the VIPA and the at least one reflector and the mirror is variable. The present invention uses the VIPA to produce a controlled variable degree of chromatic dispersion within a plurality of optical channels so as to compensate for unwanted chromatic dispersion in an optical communications system. Positional adjustment of the movable reflector holder permits variable control of the beam path length between the VIPA and the focusing lens.

Abstract: An apparatus and associated method are provided to compensate for temperature-induced drift in the center wavelength of an optical filter, such as an interference filter or an etalon filter. Interference filters can be used to filter out one among a number of narrow, closely-spaced channels in an optical wavelength division multiplexed (WDM) communications system. Etalon filters can be used to lock the output wavelength of distributed feedback lasers and in other related applications. The center wavelength of interference filters and etalon filters changes with both temperature and the angle of incidence of the optical beam. The apparatus and associated method of the invention use a positioner with a different coefficient of thermal expansion to adjust the angle of incidence of the filter as the temperature changes, thereby offsetting the temperature-induced center wavelength change.

Abstract: Method of fabricating an optical waveguide grating having a plurality of grating lines of refractive index variation including (i) repeatedly exposing a spatially periodic writing light pattern onto a photosensitive optical waveguide; and (ii) moving at least one of the writing light pattern and the waveguide between successive exposures of the writing light pattern, so that each of at least a majority of the grating lines is generated by at least two exposures to different respective regions of the writing pattern.

Abstract: An optical filter apparatus and a method of designing an optical filter having a target loss wavelength characteristic. The optical filter is formed by combining a plurality of optical parts, each having a periodic loss wavelength characteristic with respect to the wavelength. The loss wavelength characteristic may be determined using a theoretical equation that includes phase and amplitude determining parameters. Nonlinear fitting is used to determine first optimum solutions for respective phase determining parameters from predetermined numerical values. Additionally, groups of numerical values are determined from numerical ranges in the vicinities of the first optimum solutions and nonlinear fitting analysis. Consequently, optimum solutions are successively calculated and respective parameters are determined to reach final optimum solutions. Finally, the determined parameters are used to approximate the loss wavelength characteristic of the optical filter.

Abstract: A tunable Fabry-Perot filter includes an optical cavity bounded by a stationary reflector and a deformable or movable membrane reflector. A second electrostatic cavity outside of the optical cavity includes a pair of electrodes, one of which is mechanically coupled to the movable membrane reflector. A voltage applied to the electrodes across the electrostatic cavity causes deflection of the membrane, thereby changing the length of the optical cavity and tuning the filter. The filter with the movable membrane can be formed by micro device photolithographic and fabrication processes from a semiconductor material in an integrated device structure. The membrane can include an inner movable membrane portion connected within an outer body portion by a pattern of tethers. The tether pattern can be such that straight or radial tethers connect the inner membrane with the outer body. Alternatively, a tether pattern with tethers arranged in a substantially spiral pattern can be used.

Abstract: A multilayer polymer film has an optical stack including a plurality of alternating polymer layers with skin layers having mechanical, optical, or chemical properties differing from those of the layers in the optical stack, wherein the refractive indices in the in-plane direction nx and ny, and the refractive index in the thickness direction nz for each layer are all selected to obtain optical effects such as reflection, transmission, and/or polarization.

Abstract: A multilayered polymer film includes a first set of optical layers and a second set of optical layers. The first set of optical layers is made from a polyester which is often birefringent. The polyesters of the first set of optical layers typically have a composition in which 70-100 mol % of the carboxylate subunits are first carboxylate subunits and 0-30 mol % are comonomer carboxylate subunits and 70 to 100 mol % of the glycol subunits are first glycol subunits and 0 to 30 mol % of the glycol subunits are comonomer glycol subunits, where at least 0.5 mol % of the combined carboxylate and glycol subunits are comonomer carboxylate or comonomer glycol subunits. The second set of optical layers comprise copolyesters wherein 0.01 to 2.5 mol % of the combined carboxylate and glycol subunits are carboxylate subunits derived from compounds having three or more carboxylate or ester functionalities, glycol subunits derived from compounds having three or more hydroxyl functionalities, or combinations thereof.

Abstract: A method of fabricating optical filter is disclosed. The method includes providing the substrate and selectively etching the substrate to form a plurality of freestanding layers. A plurality of dielectric layers is disposed over an outer surface of each of the freestanding layers. The resultant optical filters may be used in a variety of applications including etalon applications.

Abstract: Methods and apparatuses for filtering optical channels to provide, for example, an interleaver, or a deinterleaver. A multi-plate comb filter is used to separate subsets of channels and for mixing subsets of channels. Interleavers and deinterleavers having one or more multi-plate comb filters can be used to increase the bandwidth of an optical network. The interleavers and deinterleavers can be used to interface components designed for a first channel spacing to components designed for a second channel spacing.

Abstract: A tunable Fabry-Perot filter includes an optical cavity bounded by a stationary reflector and a deformable or movable membrane reflector. A second electrostatic cavity outside of the optical cavity includes a pair of electrodes, one of which is mechanically coupled to the movable membrane reflector. A voltage applied to the electrodes across the electrostatic cavity causes deflection of the membrane, thereby changing the length of the optical cavity and tuning the filter. The filter with the movable membrane can be formed by micro device photolithographic and fabrication processes from a semiconductor material in an integrated device structure. The membrane can include an inner movable membrane portion connected within an outer body portion by a pattern of tethers. The tether pattern can be such that straight or radial tethers connect the inner membrane with the outer body. Alternatively, a tether pattern with tethers arranged in a substantially spiral pattern can be used.

Abstract: An interference filter (10, 30, 50, 70, 90, 110, 130, 150, or 190) filters selected wavelengths by dividing an input beam into two or more intermediate beams having different optical path lengths and by recombining the intermediate beams into an output beam that is modified by interference between the intermediate beams. An optical path length difference generator (20, 40, 60, 80, 100, 120, 140, 160, or 200) varies the optical path lengths of the intermediate beams by changing the physical lengths of their paths or the refractive indices of the mediums in which they are conveyed. The optical path length generator (20) of one exemplary embodiment (10) includes a spacer plate (20) that is divided into elements (22 and 24) having different refractive indices for varying the optical path lengths of the intermediate beams.

Abstract: An etalon comprising a first plate and a second plate positioned in parallel to one another and separated by a given distance, a single block spacer extending the given distance between the first plate and the second plate, and the single block spacer defining a chamber extending the given distance between the first plate and the second plate.

Abstract: A method and circuit is disclosed wherein two waveguides coupled to an optical resonator are further coupled such that beams propagating therein interfere with one another to provide a desired output response. In one embodiment, multiplexed channels of light can be demultiplexed by the device described heretofore, or alternatively, the phase relationship between these two beams can be altered prior to their being combined to provide, for example, a linearized output response useful in applications such as wavelength locking.

Abstract: An optical apparatus for producing chromatic dispersion. The apparatus includes a virtually imaged phased array (VIPA) generator, a mirror and a lens. The VIPA generator receives an input light at a respective wavelength and produces a corresponding collimated output light traveling from the VIPA generator in a direction determined by the wavelength of the input light, the output light thereby being spatially distinguishable from an output light produced for an input light at a different wavelength. The mirror has a cone shape, or a modified cone shape. The lens focuses the output light traveling from the VIPA generator onto the mirror so that the mirror reflects the output light. The reflected light is directed by the lens back to the VIPA generator. In this manner, the apparatus provides chromatic dispersion to the input light.

Abstract: A coloring structure includes a light-reflecting base, a brilliant layer placed on the base, and transparent brilliant units contained in the brilliant layer, each brilliant unit including an alternate lamination of at least two polymers having different refractive indexes, the lamination producing interfered light resulting from reflection and interference of light and transmitted light resulting from transmission of light, each brilliant unit controlling interfered and transmitted lights. The coloring structure is provided with a coloring mechanism for producing at least an interference color resulting from interfered light, a first object color resulting from reflection of transmitted light produced by the base, and a second object color resulting from reflection of incident light produced by the base without striking any brilliant units.

Abstract: An interference filter (10, 30, 50, 70, 90, 110, 130, 150, or 190) filters selected wavelengths by dividing an input beam into two or more intermediate beams having different optical path lengths and by recombining the intermediate beams into an output beam that is modified by interference between the intermediate beams. An optical path length difference generator (20, 40, 60, 80, 100, 120, 140, 160, or 200) varies the optical path lengths of the intermediate beams by changing the physical lengths of their paths or the refractive indices of the mediums in which they are conveyed. The optical path length generator (20) of one exemplary embodiment (10) includes a spacer plate (20) that is divided into elements (22 and 24) having different refractive indices for varying the optical path lengths of the intermediate beams.

Abstract: A low emissivity film which comprises: a substrate; and a coating of oxide and metallic films alternately formed on the substrate in a total of (2n+1) layers where n is an integer being equal to or more than 1, with the innermost layer being an oxide film, wherein the oxide film (B) formed on the outer side of the metallic film (A) being most apart from the substrate, has an internal stress which is equal to, or less than 1.1×1010 dyne/cm2.