Abstract: An optoelectronic device including a header having an upper surface and including a plurality of conducting pins extending up through the upper surface; an optical device; a tunable optical filter, wherein the optical device and the tunable optical filter are arranged in a vertical stack mounted on and extending above the upper surface of the header and wherein the tunable optical filter is electrically connected to the plurality of conducting pins; and a cap affixed to the header and along with the header defining a sealed interior containing the optical device and the tunable optical filter, wherein the cap has a top surface with a window formed therein, and wherein the window is aligned with the tunable optical filter and the optical device.

Abstract: Optical systems of the present invention include an electrical signal distortion compensator configured to electrically distort an electrical signal to offset optical distortion imposed by a Fabry-Perot filter on an optical signal corresponding to the electrical signal. The electrical signal distortion compensator can be used in an optical transmitter to distort the electrical signal prior to optical transmission, or in an optical receiver after optical transmission. The distortion compensation can be performed on a baseband signal or a modulated electrical carrier. Likewise, the distortion compensator can be deployed in combination with an optical receiver, which allows the use of the F-P filter-optical receiver combination with transmitters and receivers that do not include F-P filters or distortion compensators.

Abstract: An electrically variable optical filter includes a first optical element including a first angled face and a second optical element including a second angled face. The second angled face is substantially parallel to and spaced apart from the first angled face. At least one separation actuator is affixed between the first optical element and the second optical element and is operable to change a separation distance D between the first angled face and the second angled face. Light waves transmitted through the first optical element are selectively transmitted through to or reflected away from the second optical element as a function of wavelength and the separation distance D.

Abstract: A color shifting multilayer interference film is provided which may be used to produce foils or flakes for use in pigment compositions and colorants having color shifting properties. The flakes can be interspersed into a pigment medium to form paints, inks, or cosmetic preparations which can subsequently be applied to objects, papers, or people. Three and five layer designs of the interference film include alternating layers of a dielectric material and carbon in various configurations. The dielectric layers are formed to have an optical thickness at a design wavelength that provides a color shift as the angle of incident light or viewing angle changes.

Abstract: A color shifting multilayer interference film is provided which may be used to produce foils or flakes for use in pigment compositions and colorants having color shifting properties. The flakes can be interspersed into a pigment medium to form paints, inks, or cosmetic preparations which can subsequently be applied to objects, papers, or people. Three and five layer designs of the interference film include alternating layers of a dielectric material and carbon in various configurations. The dielectric layers are formed to have an optical thickness at a design wavelength that provides a color shift as the angle of incident light or viewing angle changes.

Abstract: An optical switch element is described, which includes a fixed layer disposed outwardly from a substrate and a movable mirror assembly disposed outwardly from the fixed layer. The moveable mirror assembly is operable to move relative to the fixed layer responsive to a voltage applied to the movable mirror assembly. In a particular embodiment, the movable mirror assembly includes an inner strip spaced apart from the fixed layer by a first distance and an outer strip disposed approximately adjacent to the inner strip and spaced apart from the fixed layer by a second distance which is greater than the first distance. The optical transmission of the optical switch element changes depending on the position of the movable mirror assembly.

Abstract: A MEM s scanning device has a variable resonant frequency. In one embodiment, the MEMs device includes a torsion arm that supports an oscillatory body. In one embodiment, an array of removable masses are placed on an exposed portion of the oscillatory body and selectively removed to establish the resonant frequency. The material can be removed by laser ablation, etching, or other processing approaches. In another approach, a migratory material is placed on the torsion arm and selectively stimulated to migrate into the torsion arm, thereby changing the mechanical properties of the torsion arm. The changed mechanical properties in turn changes the resonant frequency of the torsion arm. In another approach, symmetrically distributed masses are removed or added in response to a measured resonant frequency to tune the resonant frequency to a desired resonant frequency. A display apparatus includes the scanning device and the scanning device scans about two or more axes, typically in a raster pattern.

Abstract: A tilt mirror Fabry-Perot tunable filter comprises a frame and a first mirror structure. A tether system connects the first mirror structure to this frame. The tether system is designed to enable the tilting of the first mirror structure relative to an optical axis, in addition to translation of the first mirror structure along the optical axis. A second mirror structure is further provided to define an optical cavity in combination with the first mirror structure. At least two drive electrodes are provided for electrostatically tilting and translating the first mirror structure. The resulting MEMS Fabry-Perot tunable filter is capable for hitless tuning. It can be tuned to between bands directly, i.e., without dropping intervening bands.

Abstract: An actuator mechanism for a tunable optical filter unit that filters a selected wavelength band of the input light from a DWDM input light. The input light comprises a plurality of wavelength bands or optical channels of light, each of which are centered at a respective channel wavelength. The actuator mechanism exerts a substantially linear force to strain or stress a tunable optical filter element to a desire reflection wavelength(s). A controller, in accordance with a control algorithm, provides a drive signal to the actuator mechanism in response to a command signal and a feedback signal indicative of the center wavelength of the desired optical channel(s) to be filtered. The actuator mechanism includes a drive mechanism that translates linearly a slide in response to the drive signal.

Abstract: Light entering a first port is incident to an etalon filter, suffers a loss according to a loss characteristic of the etalon filter, and is fed into a first optical path. The light incident through the first optical path to a half mirror is split into two beams and the beams are fed into a second optical path and a third optical path. The beam fed into the second optical path travels forward and backward between the half mirror and a first reflector to return to the half mirror. The beam incident to the half mirror is split into two beams and the beams are fed into a fourth optical path and a fifth optical path. The beam fed into the third optical path travels forward and backward between the half mirror and a second reflector to return to the half mirror. The beam incident to the half mirror is split into two beams and the beams are fed into the fourth optical path and the fifth optical path.

Abstract: A Fabry-Perot filter device for selectively transmitting three wavelength bands of infrared radiation, including a reference light band, wherein the filter device comprises a fixed mirror formed on a substrate; a movable mirror arranged opposite to the fixed mirror with a gap formed therebetween so that the movable mirror is displaced with respect to the fixed mirror by applying an external force; a fixed electrode formed on the fixed mirror; and a movable electrode formed on the movable mirror and arranged opposite to the fixed electrode wherein the movable electrode is displaced by applying a potential difference across the fixed and movable electrodes so that the width of the gap is varied in at least three steps, whereby at least three wavelength bands of infrared radiation are selectively transmitted through the filter device.

Abstract: Thin film filters have been a basic building block of many wavelength division multiplexed (WDM) systems providing the means by which a signal, defined by a center wavelength, can be separated from a group of WDM signals. In an effort to maintain the same performance over a range of operating temperatures, thin film filters have been coated onto specially designed substrates, which expand and contract with the change in temperature to counteract the effects that the temperature change has on the thin film filters. Unfortunately, only very few materials provide the necessary thermal expansion characteristics to counteract the shift in center wavelength. Moreover, the application of a force onto only one side of the filter causes the thin film filter to bend or curve. Accordingly, the present invention solves the aforementioned problems by providing a thin film filter sandwiched between a substrate and a superstrate, which apply equal forces to each side of the filter.

Abstract: A method and apparatus for variable optical attenuation is disclosed. A variable optical attenuator is provided having a housing. Within the housing, a filter is mounted on a drive shaft of a motor such that the drive shaft passes through a substantially center point of the filter. The filter has a monotonically increasing filter gradient that begins at a lower optical density and gradually increases in optical density in a diametrical pattern. An input optical fiber provides a light signal to be attenuated. The input optical fiber introduces the light signal, which passes through a first collimator, through the filter, through a second collimator, and to an output optical fiber which exits the housing. When activated, the motor rotates the drive shaft to position the filter to a desired attenuation position for attenuating the light signal.

Abstract: A color shifting multilayer interference film is provided which may be used to produce foils or flakes for use in pigment compositions and colorants having color shifting properties. The flakes can be interspersed into a pigment medium to form paints, inks, or cosmetic preparations which can subsequently be applied to objects, papers, or people. Three and five layer designs of the interference film include alternating layers of a dielectric material and carbon in various configurations. The dielectric layers are formed to have an optical thickness at a design wavelength that provides a color shift as the angle of incident light or viewing angle changes.

Abstract: A wavelength reference (10) including at least one gas-tunable etalons (12). Each etalon (12) has first and second reflective surfaces (20,22), making a reflecting surface pair (23). Each reflecting surface pair (23) surrounds a cavity (16) which is filled with a gas-tunable medium (19) having a variable optical index of refraction. The etalons (12) produce equally-spaced spectral lines (4) which are variable in response to changes in the gas-tunable medium (19) such as varying gas pressure or composition. The spectral lines (4) are tuned to align to an external wavelength standard, preferably an ITU reference grid (2). The properties of the gas-tunable medium (19) are then fixed, preferably by sealing an enclosure (14) which surrounds the etalons (12), so that they act as a wavelength reference (10).

Abstract: An electrostatically driven optical membrane comprises a support structure and a membrane structure separated from the support structure by an electrostatic cavity. Stiction plugs are formed in the membrane structure. The plugs extend from a surface of the membrane. In one implementation, the plugs are hollow to allow a subsequent release process in which the sacrificial layer is removed.

Abstract: The present invention relates to a micro-electromechanical optical attenuator and a method of operating the same. In prior art attenuators, the attenuation obtained from a deflection angle does not change uniformly over a range of interest. In addition, over a range of interest the required voltage to obtain a desired deflection changes as a nonlinear function. The cause of the poor control of prior art attenuators can be viewed graphically by examining the attenuation as a function of deflection, and the angle of deflection as a function of voltage. These functions combine to produce a very unstable voltage to attenuation response function. The present invention has found that by operating an electrostatic drive of a reflective optical attenuator in order to attain a low loss state with the mirror in a fully deflected position, the drive voltage can be reduced to increase attenuation in a very stable nearly linear attenuation vs. drive voltage response. The non-linearity of the attenuation vs.

Abstract: The invention provides an optical filter having first wave retarding element for receiving an optical signal including a plurality of wavelengths, said first wave retarding element having a first periodic output response of a first phase versus wavelength for the optical signal. The optical signal is polarized when being launched into the first wave retarding element. A second wave retarding element receives the optical signal from the first wave retarding element. The second wave retarding element has a second periodic output response of a second phase versus wavelength for the optical signal. The first periodic output response and the second periodic output response are different from each other and non-integer multiples of each other. Advantageously, the gain flattening filter is tunable, cost effective, and compact in size. It is capable of producing any desired spectral curve without PDL by simply adjusting the angle of each wave retarding means.

Abstract: This invention relates to invention relates to a variable slope optical filter in the form of a Fabry-Perôt etalon having an end face with a variable finesse. A method for filtering and a variable slope optical filter for in-line use with an optical amplifier signal is also disclosed. The filter has a wavelength response that is substantially linear in slope within a band of operation wavelengths of the amplifier; the slope of the filter in an operating band of wavelengths is between zero and a only one of a positive or negative number; furthermore the filter has an amplitude response that has an opposite and counter slope as a function of wavelength to that of a gain tilt of the amplifier within the operation band of wavelengths. Relative movement between the filter and the optical amplifier signal is provided to vary the slope of the filter by means of varying the amplitude wavelength response of the 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 variable dispersion compensator comprising an optical incidence/output device for propagating wavelength division multiplexed light; an optical multiple reflector on which the wavelength division multiplexed light emitted from the optical incidence/output device is incident for repetitive reflections; and an optical reflection device for reflecting the wavelength division multiplexed light emitted from the optical multiple reflector toward the optical multiple reflectors the device composed of a second lens and a reflecting element and being capable of controlling the distance from the optical multiple reflector. A temperature adjusting element and a temperature detecting element are arranged via a thermal-conductive elastic member on a surface of the optical multiple reflector at a portion where no drop occurs in the intensity of the wavelength division multiplexed light incident/emitted. The temperature of the optical multiple reflector is controlled by a controller.

Abstract: A thin film electrical optical filter includes a thin film electrooptical dielectric having a voltage controlled electrooptical refractive index that is disposed between opposing stacks of alternative layers having differing refractive indices for transmitting received incident light through a target passband. An applied voltage to the electrooptical dielectric can serve to alter the actual passband to the target passband for compensating for thin film manufacturing tolerances for producing controllable optical filters with precise passbands.

Abstract: A method and system for filtering an optical signal is disclosed. The method and system comprise providing a polarization beam splitter, first and second rotators, a liquid crystal tunable filter, and first and second prisms. The polarization beam splitter splits the optical signal into two components based on polarization. The first rotator rotates a polarization 45 degrees in a first direction and is located between the liquid crystal tunable filter unit and the polarization beam splitter. The liquid crystal tunable filter unit includes liquid crystal molecules aligned 45 degrees clockwise relative to the vertical direction and is placed between the first rotator and the second rotator. The second rotator rotates the polarization 45 degrees opposite to the first direction. The first prism is located near the second rotator, while the second prism is near the beam splitter.

Abstract: A tilt mirror Fabry-Perot tunable filter comprises a frame and a first mirror structure. A tether system connects the first mirror structure to this frame. The tether system is designed to enable the tilting of the first mirror structure relative to an optical axis, in addition to translation of the first mirror structure along the optical axis. A second mirror structure is further provided to define an optical cavity in combination with the first mirror structure. At least two drive electrodes are provided for electrostatically tilting and translating the first mirror structure. The resulting MEMS Fabry-Perot tunable filter is capable for hitless tuning. It can be tuned to between bands directly, i.e., without dropping intervening bands.

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 real-time control system for an optical phased array is disclosed that comprises a computationally efficient algorithm for calculating phase differences between a plurality of array beamlets and a reference plane wave and further generates phase correction signals that are transmitted to a plurality of phase modulators to realign the array beamlets to compensate for external perturbations and atmospheric aberrations. The phase measurements are based on a phase angle of a complex number comprising square wave functions, and alternately, based on a phase angle of a complex number comprising sine and cosine functions to correct for harmonic content of phase measurements. Furthermore, the phase correction signal is based on the phase measurement times modulo2&pgr;.

Abstract: A method and device is disclosed for relaying a narrow diameter collimated optical beam carrying optical communication signal channels between a multilayer interference filters and another reflective surface avoiding signal loss by routing the optical beam to compensate for beam broadening caused by the multilayer interference filter. The method and device are particularly applicable to dispersion compensating filters, especially those wherein one filter is tunable, in that a controllable amount of dispersion is introduced to offset or compensate dispersion. Preferably one of the filters is a tunable periodic device in the form of a multi-cavity etalon structure. In a preferred embodiment of the filters can be designed to provide various controllable but different constant amounts of dispersion.

Abstract: An optical resonator is designed to suppress higher order transverse spatial modes. Higher order transverse modes in the inventive optical resonator are forced to be unstable, and ultimately achieving single transverse mode resonator operation. Specifically, the mirror shape or intracavity lens profile is tailored to bound the lower order modes while rendering the higher order modes unstable. This has application in MEMS/MOEMS devices by reducing side mode suppression ratio (SMSR) dependence on alignment tolerances, for example.

Abstract: An inexpensive and efficient tunable electromagnetic filter is disclosed, having a wide range of tunable frequencies, comprising a holder with a number of filters mounted on the holder. The frequency of the filter is altered by moving the holder relative to a beam striking the holder so that one of the filters is filtering the beam. The frequency to be filtered may be easily and quickly changed, without altering the structure of the filter. In one embodiment the tunable filter is a disk rotatable by a motor with a number of fixed frequency filters mounted around the periphery of the disk. The filter is surrounded by four fibers providing and receiving beams, as with known add-drop filters.

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 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: The present invention relates to a system and method for tunable dispersion compensation that uses a first reflective surface and a second reflective surface. The first reflective surface has a gradient reflective index and receives an input signal at an incident position. The first reflective surface and the second reflective surface process the input signal according to a dispersion function that is based at least in part upon the incident position of the input signal.

Abstract: The present invention provides a multi-channel tunable filter and methods for making such a filter. In one embodiment, the filter comprises a bank of gratings imprinted into a filter material, such as Lithium Niobate. In another embodiment, the filter comprises a bank of gratings imprinted on a thin-film filter. An optical read-head comprising a pair of lenses is configured to pass light from within an optical fiber carrying multiple wavelengths through an appropriate grating to extract or drop a specific wavelength. To ensure continuous data transmission, the filter is tuned to a wavelength by configuring the read-head to move in a hitless manner. In one embodiment, the gratings are recorded by the interference of two beams. A first plane wave reflects off a first mirror stack and a second plane wave reflects off a second mirror stack. In another embodiment, the gratings are recorded by a phase masking method.

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 wavelength tunable optical filter 14 and a method of making the same. The optical filter 14 comprising two back-to-back Fabry-Perot optical cavities 30 & 40 comprising a fixed mirror 31 common to both cavities with parallel displaceable mirrors 32 & 42 located one on each side of the fixed mirror 31 to adjust the overall known length of the respective cavities. One optical cavity may have greater length than the other optical cavity.

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: 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: A tunable filter system comprises a signal source providing a WDM having multiple channels, or other signal requiring spectral analysis, within a spectral signal band. A reference signal source is also provided that generates a reference signal with spectral features, such as narrow spectral lines, that are located within a spectral reference band. A tunable filter functions as a band pass filter in transmission and a notch filter in reflection. It is controlled to filter both the reference signal and the WDM signal. A transmission detector is provided to detect the signal transmission through the tunable filter and a return detector is provided to detect the signal that is returned from the filter. Embodiments of the invention rely on a characteristic of a class of tunable filters, such as Fabry Perot etalons, in which light that is not transmitted through the filter is reflected. Thus, while the tunable filter appears as a band pass filter in transmission, it functions as a notch filter in reflection.

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. The modified cone shape of the mirror can be designed so that the apparatus provides a uniform chromatic dispersion to light in the.

Abstract: An optical irregular phased-array is disclosed. The effective positions of the phase-controlled elements in the phased-array form an irregular array, such that the size of each phase-controlled element can be much larger than the wavelength of the light without having multiple beam problem. The effective phased-array is a virtual array of effective point-source of light, which is generated by an array of lenses or mirrors. An array of space-fed phase-modulators that is coupled with the array of lenses or mirrors provides means of adjusting the phase of the light from each effective point-source of light. While, the array of phase-modulators and array of lenses or mirrors can all be a regular array, which are simple in structure. A sub-array technique is provided to greatly reduce the controlling lines.

Abstract: An optical filter assembly is provided which includes a first optical filter and a first counteracting ring. The first optical filter is of a filter material that transmits a selected transmission range within a wider range of wavelength of light, and reflects another selected reflection range of the wavelengths. The filter material has a refractory index, whereby heating of the first optical filter tends to cause an increase in refractory index with a corresponding increase in the transmission range in a first direction. The counteracting ring is attached to the first optical filter so that at least some of the light transmits through an aperture in the counteracting ring. Heating of the first counteracting ring causes enlargement of the first counteracting ring, which stretches the first optical filter. The selected transmission range is thereby at least partially stabilized.

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 polarization independent tunable optical filter comprises an inherently polarization sensitive angle-tuned filter element and polarization-maintaining multi-pass optics for directing a light beam to and fro through the tunable filter element while maintaining its linear state of polarization. An optical spectrum analyzer apparatus comprises such a tunable optical filter in combination with a polarization control unit for decomposing a light beam for analysis into first and second beams having mutually orthogonal states of polarization (SOPs) and then adjusting one or both SOPs so that they are parallel to each other and to one of the principal axes of an inherently polarization sensitive angle-tuned filter which selects different wavelengths of the first and second light beams. The light beams are passed through the filter repeatedly by multi-pass polarization-maintaining optics.

Abstract: The invention provides improved optical devices, systems, and methods for controllably varying an optical characteristic of an optical signal, particularly for filtering and generating optical signals about a narrow tunable central wavelength. Thin film multi-cavity Fabry-Perot bandpass filters have film thicknesses which vary so as to vary the center wavelength of the filter's pass range. Novel micro lenses and lens arrangements avoid transmission of optical signals through a large area of the optical filter, which would widen the effective pass bandwidth and reduce coupling efficiency. These bandpass filtering techniques can be used in an external cavity laser system to provide a tunable laser source.

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: 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 tunable filter includes a polarizer, a polarization rotator, a diffraction grating and a diffraction grating adjustor. The polarizer polarizes a light beam and splits the light beam into first and second light beams. The polarization rotator rotates a plane of polarization of the first light beam at 90° to generate a rotated light beam. The diffraction grating receives the rotated light beam and the second light beam. The diffraction grating adjustor adjusts the diffraction grating to change incident angles of the rotated light beam and second light beam.

Abstract: An optical multilayer structure material has a structure such that, on a substrate, a conductive layer in contact with the substrate, a gap portion having a size that enables an interference phenomenon to occur and can be changed, and an optical thin film are formed in this order. The circumference of a movable portion in the optical thin film is uniformly supported by supporting portions, suppressing generation of strain due to an internal stress. Through holes are formed in the movable portion to allow an etchant to easily reach a sacrifice layer when forming a gap portion by etching for sacrifice layer. There is provided an optical multilayer structure material having a simple construction, which can suppress generation of strain due to an internal stress and can be advantageously used in an image display apparatus.

Abstract: A tunable filter system comprises a signal source providing a WDM having multiple channels, or other signal requiring spectral analysis, within a spectral signal band. A reference signal source is also provided that generates a reference signal with spectral features, such as narrow spectral lines, that are located within a spectral reference band. A tunable filter functions as a band pass filter in transmission and a notch filter in reflection. It is controlled to filter both the reference signal and the WDM signal. A transmission detector is provided to detect the signal transmission through the tunable filter and a return detector is provided to detect the signal that is returned from the filter. Embodiments of the invention rely on a characteristic of a class of tunable filters, such as Fabry Perot etalons, in which light that is not transmitted through the filter is reflected. Thus, while the tunable filter appears as a band pass filter in transmission, it functions as a notch filter in reflection.