Abstract: Temperature compensated fiber stretching is accomplished by amplifying with a unique flexure the relative displacement between a rigid frame and a longitudinal spacing element. For passive compensation, relative displacement results from differential thermal expansion between the frame and the longitudinal spacer. For active thermal compensation and/or for wavelength tuning of an embedded fiber Bragg grating, relative displacement results from combining differential thermal expansion with active feedback length control of the longitudinal spacer. The feedback control can stabilize using length feedback from a displacement sensor or actively control length using temperature feedback, including logic elements, for example algorithms or look up tables. In an optical system, combined passive compensation and active control with flexure amplification provide superior thermal wavelength stability and tuning range.

Abstract: A miniature monolithic optical demultiplexer that comprises a dispersive optical element and a wavelength filter array. The miniature monolithic optical DWDM demultiplexer can be fabricated using micro- and nano-scale techniques common to the semiconductor industry. The operating principles and some characteristics of the DWDM demultiplexer are described. The device will be useful in the field of optical communication as a component within networks that perform all of the necessary switching, adding, dropping, and manipulating of optical signals entirely in the optical domain. With the inclusion of additional components, exemplary optical communication devices that can be built using the DWDM demultiplexer include optical add/drop multiplexers (OADM), Dense Wavelength Division Multiplexing (DWDM) routers, tunable filters, optical cross connects, and the like.

Abstract: Devices that couple variable attenuators to a single WDM multiplexer to individually adjust and control the power levels of different WDM channels, e.g., substantially equalizing the power levels of the channels. Optical reflection and in-fiber variable attenuators are implemented to simplify the device structure and reduce cost.

Abstract: A design technique minimizes the loss and ripple in the spectral response of an optical filter formed using a pair of gratings connected by an array of optical elements. This filter can be, for example, two waveguide grating routers (WGRs) connected by an array of waveguides. Each WGR includes two star couplers connected by waveguide grating arms. The smoothest spectral response is achieved for a given set of connecting waveguides, by choosing the number of grating arms less than or equal to filling the star coupler central Brillouin zone made by the set of connecting waveguides resulting in the connecting waveguides neither substantially over- or under-sampling the optical spectrum from the waveguide gratings. Exactly filling the Brillouin zone with the grating arms minimizes the loss, and so is the preferred choice.

Abstract: This invention relates to a diffraction grating device having a refractive index modulation formed in an optical waveguide region in a predetermined region in the longitudinal direction of the optical waveguide. In the diffraction grating device, a refractive index modulation is formed in the core region in a predetermined region in the longitudinal direction of the optical waveguide. In this diffraction grating device, the optical period of the refractive index modulation is substantially constant, the phase of the refractive index modulation is inverted at a phase inversion portion, and the number of phase inversion portions is one or two. In this diffraction grating device, the absolute value of a parameter R (equation (22a)) is smaller than 0.25. According to this invention, a diffraction grating device capable of shortening the region where the refractive index modulation is formed and flattening the reflectance characteristic in the reflection wavelength band is provided.

Abstract: An optical performance monitor having a tunable fiber grating sandwiched between the first and second reflective surfaces of a fiber etalon provides high sensitivity, while simultaneously monitoring an optical data signal. Individual channels within the optical data signal are monitored by tuning the fiber grating over the wavelength range of the optical data signal to measure an intensity of each channel. As the tunable grating scans the wavelength range of interest, it simultaneously changes the resonant cavity length of the etalon, thus allowing the etalon to effectively monitor the tunable grating with a wavelength outside the wavelength range of the optical data signal.

Abstract: A fiber grating pressure sensor for use in an industrial process includes an optical sensing element 20,600 which includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20,600 may be used by itself as a sensor or located within a housing 48,60,90,270,300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20,600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50.

Abstract: An optical waveguide grating is formed in an optical waveguide core and/or in an optical waveguide cladding where an electric filed of light propagating in the core is spreading by implanting accelerated ions through a mask to the optical waveguide. The mask has enough thickness to prevent the ions irradiated to the masked parts from reaching the portion where the grating is formed. The acceleration energy of the ions is chosen to make the lateral straggling of the implanted ions in the optical waveguide less than three fourths of the period of the grating, or the acceleration energy is chosen to make all or a part of the implanted ions pass through the portion where the grating is formed.

Abstract: An optical delay generator includes a waveguide made from electro-optically active material which contains a chirped distributed Bragg reflector. An electric field generated across the waveguide causes the index of refraction within the waveguide to change. A change in the index of refraction results in a change in the point at which light is reflected from the chirped distributed Bragg reflector within the waveguide, thus providing a controllable delay for optical pulses. Optical pulse position modulation is provided by using the optical delay generator to control the delay imparted on each pulse within a stream of equally-spaced optical pulses.

Abstract: An optical signal processing apparatus includes a first optical waveguide and a first slab waveguide configured to equally distribute an output light of the first optical waveguide. A first arrayed waveguide includes an aggregate of optical waveguides changing in optical length by a constant interval for dividing the output light. A second slab waveguide focuses the optical output of the first arrayed waveguide. A spatial filter receives incident light focused by the second slab waveguide and distributes the incident light on a straight line. The spatial filter also modulates the light into a desired amplitude according to the position on the straight line. The apparatus also includes a second arrayed waveguide and an aggregate of optical waveguides changing in optical length by a constant interval for applying light modulated by the spatial filter to the second arrayed waveguide. Structure is provided for converging the output light of said second arrayed waveguide to a single point.

Abstract: A miniature monolithic optical add-drop multiplexer that comprises a dispersive optical element, a wavelength filter array and a diverter. The miniature monolithic optical DWDM add-drop multiplexer can be fabricated using micro- and nano-scale techniques common to the semiconductor industry. The operating principles and some characteristics of the DWDM add-drop multiplexer are described. The device will be useful in the field of optical communication as a component within networks that perform all of the necessary switching, adding, dropping, and manipulating of optical signals entirely in the optical domain.

Abstract: An optical wavelength tunable filter includes an optical waveguide having a first branched optical waveguide and a second branched optical waveguide merging into one piece of the optical waveguide through which optical wavelength multiplexed signals, each having a different wavelength component being incident from an end face of the first branched optical waveguide, are propagated. A comb-type electrode (or a plurality of comb-type electrodes each corresponding to each of the different wavelength-components) is mounted vertically to apropagating direction of the optical wavelength multiplexed signals leaving a specified space apart from the optical waveguide formed by a merger of the branched first branched optical waveguide with the second branched optical waveguide. A voltage applying device applies a predetermined voltage to each of the comb-type electrodes.

Abstract: The present invention relates generally to electro-optically active waveguide segments, and more particularly to the use of a selective voltage input to control the phase, frequency and/or amplitude of a propagating wave in the waveguide. Particular device structures and methods of manufacturing are described herein.

Abstract: An optical filter is manufactured by placing a photosensitive optical fiber in a spiral arrangement on a fiber holder, preferably having a spiral groove for holding the fiber, and exposing the fiber to ultraviolet light through a phase mask having a spiral diffraction grating, forming an in-fiber Bragg grating. The fiber can be conveniently scanned by an ultraviolet beam as the fiber holder and phase mask turn on a rotating stage. The fiber can be compactly packaged between the fiber holder and a cover. The fiber holder and cover can be formed by coating a substrate with layers of polymer material, the spiral groove being formed by photolithographic patterning of one of the layers.

Abstract: An optical fiber is stressed along its axis with a strain of at least 1% while light is introduced transversely to write a grating. The strain increases the photosensitivity of the fiber and reduces the time required to write the grating. Alternatively, the fiber can be compressed radially and inwardly, or compressed along its axis.

Abstract: Fiber Bragg writing devices comprising solid state lasers are provided. The solid state lasers comprise optical parametric oscillators and emit moderate peak-power output beams at wavelengths which are suitable for efficient production of fiber Bragg gratings without causing embrittlement of the optical waveguide. These solid state lasers generate output beams with wavelengths of approximately 240 nm, in order to match the primary absorption peak in the ultraviolet range for a typical optical waveguide. Some of these solid state lasers generate tunable wavelength beams using an optical parametric oscillator (“OPO”), then generate harmonics of these tunable beams. Other lasers mix the tunable beam with fixed wavelengths derived from the pump laser to reach the desired output wavelength.

Abstract: A micro-opto-electro-mechanical systems (MOEMS) modulator based on the phenomenon of frustrated total internal reflection (FTIR). The modulator effects amplitude and phase modulation at the boundary of a waveguide. Wavelength-specific switching is achieved by spatially separating the wavelength channels by dispersing a broadband input signal into its wavelength components through a grating. In exemplary embodiments, an array of micro-fabricated actuators is used to switch or modulate wavelengths individually. Applications include wavelength and space-resolved phase and amplitude modulation of optical beams, and re-configurable add/drop switching of dense wavelength-division multiplexed (DWDM) optical communication signals.

Abstract: An optical phase shifter including a constant phase shift element or a variable phase shift element, each introducing a desired and predetermined phase shift into an optical signal passing through the phase shifter. The phase shifter has coaxial first and second waveguides each with a core defining an optical path, through the first waveguide and having an output facet, and which waveguides are separated from each other by a predetermined distance. The phase shift element is disposed between the waveguides and an actuator is coupled to the phase shift element for causing selective movement of the phase shift element.

Abstract: In accordance with the invention, an optical waveguide grating with an adjustable optical spacing profile comprises a waveguide grating in thermal contact with one or more resistive film coatings. A coating extends along the length of the grating and its local resistance varies along the length of the grating. In one embodiment, a plurality of overlaping coatings are chosen so the resistance variation of each is different, thereby permitting a variety of heat generation profiles to be effected by independent control of the coatings. The different heat generation profiles, in turn, proportionately change the grating geometric spacing and local refractive index along the grating length, providing the desired adjustable optical spacing profile. Other embodiments use resistive films with abruptly changing or periodically changing heating variation.

Abstract: In the band edge region, transmission and reflection of an optical wave can be made very sensitive to the change in radiation wavelength, a change in the modulator material refractive index, and/or a change in the material absorption. Controlling these parameters with the increased level of sensitivity is provided by modulation using the band edge region. A preferred embodiment method of the invention uses a periodic optical structure (i.e., a grating) on top of an optical waveguide structure. The combination of the periodic structure and the optical waveguide is designed so that the reflection and/or transmission of the guided wave have broad pass bands with narrow transition bands. The optical structure is exposed to an incident laser radiation with wavelength in one of the transition bands. Modulation of the incident laser radiation is controlled by the change in refractive index or absorption in the optical guided wave structure produced by the modulation voltage.

Abstract: Techniques and designs for producing tunable optical dispersion by using two fiber Bragg gratings with nonlinear group delays to sequentially reflect an input optical signal and by tuning at least one of the fiber Bragg gratings.

Abstract: A bulk optic (de)multiplexer for fiber optic communications systems includes a diffraction grating having a diffraction surface, a waveguide array including a plurality of waveguides having an input/output end for emitting and receiving optical signals, and a focusing optic in optical communication between the diffraction grating and the waveguide array along an optical axis. The focusing optic focuses beams from the diffraction surface of the grating for optical coupling with the input/output ends of the waveguides. The (de)multiplexer further includes a frame. A fixed mount is provided between the focusing optic and the frame. A first adjustable mount is provided between the waveguide array and the frame and a second adjustable mount is provided between the diffraction grating and the frame. Preferably, the optical axis corresponds to a Z axis of orthogonal X, Y, Z axes and the waveguides of the waveguide array are aligned with the input/output ends along an input/output axis.

Abstract: A (de)multiplexer for use in optical communications systems includes a diffraction grating optically coupled between a multiplex optical waveguide and a plurality of single channel optical waveguides for diffracting an optical signal between a receiving/transmitting end of the multiplex optical waveguide and a receiving/transmitting end of the single channel optical waveguide. The diffraction grating has al least two surfaces optically coupled to the waveguides. Each of the surfaces is angularly displaced relative to one another a select amount such that a portion of the optical signal diffracted by each surface is offset the direction of dispersion relative to the portions of the optical signal diffracted by the other surfaces to broaden the transmission band.

Abstract: A laser-diode assembly for generating a frequency-stabilized narrow-bandwidth light comprises a light source in the form of a semiconductor laser diode coupled via a first optical coupling device to one end of a first optical fiber. The other end of this fiber is coupled to a second or an output fiber via a second optical coupling device. The assembly is characterized by the fact that a long inner cavity is formed by a section of the optical system between two oppositely directed mirrors. The first mirror is applied onto the back side of the semiconductor laser diode, and the second mirror is applied onto a flat front side of one optical lens element or onto the back side of another optical lens element. These optical lens elements are parts of an optical coupling between the first and the second fibers. The first mirror completely reflects the entire light incident onto this mirror, whereas the second mirror reflects a major part of the light, e.g., about 90% and passes only a small part, e.g.

Abstract: An optical waveguide network is formed in a substrate of an electrooptically active material. The optical waveguide has input and output facets where optical signals may be input to and output from the integrated optics chip. At least one lateral trench is formed in the substrate. The lateral trench is arranged to prevent light rays incident thereon from inside the substrate from propagating to the output facet. The lateral trench may be formed as a slot that extends toward the surface of the substrate where the optical waveguide network is formed, or the trench may be parallel to the plane of the optical waveguides.

Abstract: An acousto-optical filter having a wide tuning range and a method of making the same. An acoustic transducer is provided for generating an acoustic pressure wave of a selected frequency that is propagated longitudinally along an optical fiber member. The pressure wave generates a plurality of alternating localized compressions and rarefactions in the optical fiber such that a grating (i.e., periodic changes in the fiber's refractive index) is created therein. The grating reflects optical signals of a particular wavelength depending upon its period or pitch (i.e., Bragg resonance wavelength). The acoustic pressure wave's frequency is modulated by controlling the acoustic transducer such that a variable grating pitch is obtained, thereby causing a corresponding change in the Bragg resonance wavelength of the grating. In response, a reflected optical signal selected from incoming multiplexed optical signals tunes to a different wavelength.

Abstract: The present invention relates to a tunable optical device 10 that includes an optical fiber device 12 having optical properties that vary with temperature and a heater 14. The heater 14 is thermally coupled to the optical fiber device 12. The heater 14 includes a metal layer 18 and two electrical contacts 20, 22 that are electrically connected to the metal layer 18. The electrical contacts 20, 22 are spaced apart from one another along the metal layer 18. The electrical resistance of the portion of the metal layer 18 between the contacts 20, 22 varies with temperature and serves as a resistive heater. The invention also includes a controller 16 that is electrically connected to the heater 14. The controller 16 provides electrical power to the heater 14 and measures the electrical voltage across the heater 14. The controller 16 compares the measured electrical voltage to a pre-selected reference value. The controller then regulates the amount of electrical current supplied to the heater 14.

Abstract: This invention discloses a selectably directable optical beam defecting device including at least at least one substrate having formed thereon a multiplicity of waveguides, each waveguide receiving light and emitting light, the totality of light emitted by said multiplicity of waveguides producing at least one selectably directable output beam, and at least one multiplexer applying electrical inputs to the at least one substrate for individually controlling the light emitted by each of the multiplicity of waveguides, thereby governing the orientation of the selectably directable output beam.

Abstract: An optical device has a substrate, a polarization beam splitter, first and second pairs of optical waveguides, a transducer and a thin film. The polarization beam splitter is formed on the substrate and has input and output sides. The first and second pairs of optical waveguides are formed on the substrate to guide polarized optical signals. The first pair of optical waveguides meets at the input side of the polarization beam splitter, and the second pair of optical waveguides meets at the output side of the polarization beam splitter. The transducer is formed of a comb-tooth electrode on the substrate to excite a surface acoustic wave on the substrate and rotate the polarization of the optical signal. The thin film covers a portion of each waveguide of either the first or second pairs of optical waveguides. The thin film may be formed of silicon dioxide or indium dioxide, either with a metal oxide optionally added thereto. The speed of sound in the thin film is less than that in the substrate.

Abstract: Techniques and devices for compensating polarization-mode dispersion in an optical signal by using a nonlinearly-chirped Bragg grating in a dual-pass configuration.

Abstract: Method for optical energy transfer and energy guidance uses an electric field to control energy propagation using a class of poled structures in solid material. The poled structures, which may form gratings in thin film or bulk configurations, may be combined with waveguide structures. Electric fields are applied to the poled structures to control routing of optical energy. Techniques include frequency-selective switchable- and adjustable-tunable reflection, splitting, directional coupling, frequency-tunable switching and efficient beam combining, as well as polarized beam combining. Adjustable tunability is obtained by a poled structure which produces a spatial gradient in a variable index of refraction along an axis in the presence of a variable electric field. In one embodiment, the present invention is a method of switching a grating which consists of a poled material with an alternating domain structure of specific period.

Abstract: A semiconductor integrated circuit which has a wavelength converting function and a wavelength demultiplexing function is made up of a relatively small number of parts, allows parts to be integrated easily, and can be manufactured at a relatively low cost. The semiconductor integrated circuit includes an MMI waveguide for converting an optical signal having a second wavelength into an optical signal having a first wavelength, a first input port mounted on an entrance end of the MMI waveguide, for being supplied with the optical signal having the first wavelength, a second input port for being supplied with the optical signal having the second wavelength, and at least one output port mounted on an exit end of the MMI waveguide, for extracting the optical signal having the first wavelength. The MMI waveguide has a refractive index variable depending on the intensity of the optical signal having the second wavelength.

Abstract: An optical switch formed of a holographic optical element (HOE) disposed above a top surface of a substrate and moveable relative thereto is shown. Light is traveling through the substrate under total internal reflection, which creates an evanescent field extending beyond the reflecting surfaces of the substrate. The HOE is characterized, in one embodiment, by being formed from a plurality of strips that are moveable between a first position in which the strips are above the evanescent field and a second position in which the strips are inside the evanescent field. In the first position, the light in the substrate propagates unaffected by the HOE in a primary direction of propagation. In the second position, the light in the substrate is altered by the HOE and made to propagate in a reflected direction oblique to that of the primary direction of propagation.

Abstract: The method and apparatus of the present invention achieves the trimming and, therefore, tuning of fiber optic devices by, in on embodiment, precisely heating a small area of a fiber to allow its elongation when mounted under tension in its package. By pulsing a source of heat in precise amounts, the elongation can be precisely controlled within 1 picometer precision over a tuning range of about 200 picometers. In another embodiment with fibers having core dopants which can be diffused, the optical length of an optical fiber can be trimmed with nanometer precision. By employing a controlled source of localized energy applied to the optical fiber, real time trimming can be achieved in both systems by injecting a broad band source of energy at the input of the device and coupling a spectral analyzer at its output to monitor the frequency characteristic of the optical device during trimming.

Abstract: An electrically controllable grating is provided by forming regions 4 and 5 of different refractive index within an electro-optic material. Electrodes are provided so that a readily controllable electric field may be applied to the index grating formed by the alternating regions such that the refractive index of the regions may be varied electrically to form a controllable grating. The grating may be used as an electrically controllable distributed Bragg reflector to allow variable wavelength feedback within a laser cavity. The grating may be used to perform wavelength division multiplexing and/or frequency modulation.

Abstract: A diffraction grating for a waveguide or for externally incident light. The grating includes a substrate and an electrooptic structure extending over it. The electrooptic structure may include a waveguide having a propagation axis. A first and a second electrode structure are provided on either side of the electrooptic structure so that an electric field is generated in the electrooptic structure when a potential is applied to the electrodes. The first electrode structure has an interdigitated configuration defining a plurality of fingers. In use, respective potentials V0 and V0+&Dgr;V are applied to adjacent fingers. The diffraction grating induced in the electrooptic structure by the periodic electric field advantageously has a refractive index adjustable by varying V0 and &Dgr;V and a spatial periodicity adjustable by varying &Dgr;V.

Abstract: This invention is predicated upon applicants' discovery that the performance of thermally adjustable fiber grating devices is enhanced by disposing them within a vessel for thermal isolation. The vessel is sufficiently larger than the fiber to avoid contact with the grating yet sufficiently small to isolate the grating from substantial air currents. Conveniently, the vessel is a cylindrical tube having elastomeric end seals. Advantageously microcapillary tubes passing through the elastomeric seals provide openings for the fiber to pass through the tube.

Abstract: An integrated circuit die may have a processor and a spatial light modulator formed in the same die. An opening may be provided in an interposer to allow light to reach the spatial light modulator. A plurality of bump bonds may space the interposer from the die region including the processor. Thus, a display may be formed in an integrated fashion with a processor.

Abstract: The present invention provides photonic devices utilized in optical telecommunications. The photonic devices include photosensitive bulk glass bodies which contain Bragg gratings, particularly with the ultraviolet photosensitive bulk glass bodies directing optical telecommunications wavelength range bands. Preferably the ultraviolet photosensitive bulk glass bodies are batch meltable alkali boro-alumino-silicate bulk glass bodies.

Abstract: The present invention relates to a tuneable add/drop demultiplexer. The add/drop multiplexer includes at least one N×N MMI-waveguide (10), where N≧3, at least N-number of Michelson waveguides (31, 32, 33 and 34), at least one Bragg grating (62, 64 and 66) per Michelson waveguide (31, 32, 33 and 34) and at least one phase control element (51, 53, 55 and 57) in at least N−1 number of Michelson waveguides (31, 32, 33 and 34). The Michelson waveguides (31, 32, 33 and 34) include said phase control elements (51, 53, 55 and 57) and said Bragg gratings (62, 64 and 66) and are coupled to at least one MMI-waveguide (10). Each Michelson waveguide (31, 32, 33 and 34) can be provided with a broadband reflection section (70). The invention also relates to a method for tuneable add/drop multiplexing, the use of a wavelength selective switch as a tuneable add/drop multiplexer and the use of a tuneable add/drop multiplexer as a wavelength selective switch.

Abstract: A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device.

Abstract: The traditional solution to monitoring the pump laser power uses the back facet of the pump laser to monitor its power. However, stability and aging issues of the back facet may make it difficult or even impossible to measure the pump power to a high degree of accuracy using this method. Pump lasers often use fiber Bragg gratings to stabilize their wavelength. However, if an in-line optical fiber blazed Bragg grating is used, then the pump power is coupled out of the grating to a detector and monitored. The method of the present invention minimizes components and provides a direct monitoring of fiber coupled power. Alternatively, light coupled out of a WDM is used in a similar manner to monitor the pump power.

Abstract: Disclosed is an optical fiber, which comprises a core and a clad of a two-layer structure including an innermost layer and an outermost layer, and has a refractive index distribution structure satisfying the conditions of 0.8%≦&Dgr;1≦1.3% and −0.7%≦&Dgr;2≦−0.4%, and also satisfying the conditions of −20≦D≦0, −0.1≦S<0 and 0≦(D/S)≦200 in a specified wavelength band having a band width of at least 20 nm in a 1.5 &mgr;m wavelength band.

Abstract: An optical fiber, a section of length (Lgr) which is modulated in refractive index so as to form a grating with a plurality of characteristics reflection wavelength channels, has a refractive index modulation comprising an amplitude modulation having an underlaying higher frequency component defining the shape of the reflection profile of each of the wavelength channels and, superposed thereon, a lower frequency component of period P imposing repeated envelopes over the higher frequency component and defining the separation of the wavelength channels. In one embodiment, the lower frequency component has the shape of a sinc-function with varying refractive index (&dgr;n) and with discrete &pgr;-phase shifts (&dgr;&phgr;) each envelope, to form a sinc-sampled grating. Chirped multi-channel optical fiber gratings may thus be provided for dispersion compensation in long-haul transmission links.

Abstract: Described herein is an integrated optical device (400) having an input path (402) and an output path (420). A waveguide (430) including a Bragg grating is located in the output path (42). A plurality of control elements are located along the waveguide (430) for providing local adjustment of the Bragg grating to compensate for manufacturing errors. The control elements are conveniently thermo-optic elements, for example, resistive elements whose temperature can be changed by supplying current to them.

Abstract: The invention relates to an optical add/drop device comprising at least two optical filter units (OADE). An individual filter unit comprises a first, second and third port so that when all signals of the aggregate signal are present at the first port (A), said desired signal is present at the second port (B) and all other signals except the desired signal are present at the third port (C). To provide flexible altering possibilities, a number of filter units (OADDE . . . OADE) are placed in succession to form at least two pairs of filter units in such a way that in each pair the first filter unit operates at a given wavelength as a signal dropping unit and the second as an adding unit corresponding to the first unit, adding to the aggregate signal a signal having the same wavelength.

Abstract: A biosensor comprises a waveguide into which light is coupled by a diffraction grating. The sample to be analyzed is placed on a reaction region in which a component of the immunological reaction is provided, for example antibodies or antigens. Fluorescence is excited on the surface of the waveguide because of the presence of a marker for example, a labelled antigen or antibody. Fluorescence is decoupled from the waveguide by the coupling diffraction grating or another diffraction grating. The waveguide is made of a material emitting light when it is excited by the marker excitation beam. This latter emission has a peak wavelength different from that of the emission radiation due to the marker used in the immunological reaction. Waveguide material fluorescence emission provides a reference during measurement.

Abstract: A method for rapidly increasing the photosensitivity of an optical fiber comprising the step of providing an optical fiber comprising a glassy material and a thermally-stable coating. The thermally-stable coating has a thermally-stable exposure band, wherein desired time/temperature exposure parameters fall within the time/temperature thermal stability exposure band for the coating. The optical fiber is exposed for the desired time/temperature exposure to a hydrogen-containing atmosphere. The desired temperature is more than 250° C. and the desired time exposure does not exceed one hour. The glassy material then may be irradiated with actinic radiation, such that the refractive index of the irradiated portion results in a normalized index change of at least 10−5.

Abstract: A multiwavelength selector for use with a high speed performance monitor, that uses a spatial wavelength separator, a configurable spatial filter, a focusing assembly, and a photodetector to select a wavelength or wavelengths from a plurality of incoming wavelengths, for further processing by said high speed performance monitor. The invention is intended for use in a fiber optic network application.

Abstract: A method and apparatus for forming a tube-encased fiber grating includes an optical fiber 28 which is encased within and fused to at least a portion of a glass capillary tube 120 and a substantially transparent index-matching medium 122, such as an optically flat window, having an optically flat surface 126 adjacent to the tube 120. A substantially transparent index-matching intermediate material (e.g., UV transparent oil) 124 is used between the window 22 and the tube 120 to substantially eliminate the interface between the tube 120 and the medium 122. A pair of writing beams 26,34 are incident on and pass through the medium 122, the tube 120 and intersect and interfere in a region 30 on the fiber 28. Also, the width Wb of the writing beams 26,34 may be set to be less than the width Woil of the intermediate material 124 to eliminate surface damage (ablations) of the tube 120. Attentively, the medium 122 may have a geometry to eliminate surface ablations (e.g.