Abstract: A thin film waveguide and an optical deflecting device which have a substrate and a waveguide layer. An optical buffer layer which has a refractive index smaller than that of the waveguide layer is provided between the substrate and the waveguide layer, and the optical buffer layer has such a thickness as to make a zero mode guided light beam progressing in the waveguide layer have a propagation loss not more than 2 dB/cm and as to make a first mode guided light beam progressing in the waveguide layer have a propagation loss not less than 4 dB/cm. For example, the waveguide layer is a ZnO thin film, the substrate is a silicon substrate, and the optical buffer layer is a SiO.sub.2 thin film. Further, an interdigital transducer is provided on the waveguide layer to excite Sezawa waves as surface acoustic waves. For example, the waveguide layer is designed to have a thickness which meets the following condition: 1.0<hK<5.0 (K=2 .pi./.LAMBDA.), wherein, h is the thickness of the waveguide layer, and .

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 method of avoiding phase discontinuities between adjacent sections of a long Bragg grating written section-by-section in an optical fibre uses masks with alignment parts additional to their writing parts. Each alignment part is a replica of a portion of the writing part of the adjacent mask. The writing of the Bragg grating produces an associated absorption grating and so, for light directed in series through the alignment part of the mask and the already-written previous section of the grating, transmission is at a maximum when the mask is moved into exact registry. Fine adjustment of mask position is made to find this condition before writing with this mask is commenced.

Abstract: A light expanding system for converting a light beam generated from a point-like light source into a collimated linear or planar light beam is disclosed herein. According to an embodiment of the invention, a system for producing a linear light beam includes a beam collector and a light pipe adjacent to which a multiplicity of specially configured microprisms are located. The light expanding system according to this embodiment is suitable for use in devices utilizing a linear light beam, such as a scanner. According to another embodiment of the invention, a system for producing a planar light beam includes, in addition to the beam collector and light pipe described above, an additional light pipe with adjacent microprisms. The light expanding system according to this embodiment of the invention can be used, for example, in displays, road signs, medical research equipment, instrument meters or jewelry; to light pictures or art work; or as part of a see-through lighting system far use in dentistry and surgery.

Abstract: A progressive method of writing a long grating in a substrate using a pulsed interference fringe pattern. The substrate is moved through the fringe pattern while being continuously illuminated with light of a different wavelength to produce a diffracted beam whose phase is monitored to produce a control signal that regulates the pulsing of the writing beam to ensure that the fringe pattern is present only when it is in correct registry with the grating being written.

Abstract: A method and apparatus for writing a Bragg grating in a photosensitive optical waveguide is disclosed. The novel method comprises an interferometer having precisely adjustable light collecting and directing components. A phase mask illuminated with ultraviolet light is used as the interferometer light source. The adjustability of the interferometer allows the writing of Bragg gratings for filtering wavelengths in the range 1275 nm to 1575 nm while adjusting the appropriate interferometer elements by only +/-0.75.degree. each.

Abstract: A Bragg grating is produced in a semiconductor component by wet etching through a resin mask developed after holographic exposure. This causes the regions of the grating at the boundary of other parts of the component to be etched more deeply. To compensate this, the method includes further irradiation through a second mask disposed at a distance from the part of the resin mask that defines the location of the grating. Applications include opto-electronic components.

Abstract: An optical deflector which has a waveguide, an interdigital transducer which is provided on the waveguide to convert a high-frequency signal to excite surface acoustic waves, a light incidence section for making a light beam incident to the waveguide and a light emergence section for making a light beam progressing in the waveguide emergent therefrom, and a scanning optical system provided with the optical deflector. The interdigital transducer is a chirp type and has finger electrodes which are so designed that an emergent light beam from the optical deflector will have a substantially fixed intensity in a deflection range. More specifically, the finger electrodes of the interdigital transducer are overlap-weighted so that an emergent light beam from the optical deflector will have a substantially fixed intensity in a deflection range.

Abstract: An acoustooptical wavelength device for wavelength selection includes one substrate of a birefringent and photoelastic material on which there is formed: first and second rotation stages of the polarization plane of an optical signal in a first wavelength interval, wherein each stage comprises at least one optical waveguide traveled over by the signal; at least one optical waveguide, connecting the two stages and carrying one single polarizer consisting of an evanescent-wave polarization coupler; and at least one optical waveguide carrying one polarizer being finally provided downstream of the second stage.

Abstract: Optical energy transfer devices and energy guiding devices use an electric field to control energy propagation using a class of poled structures in solid material in channel dropping filter and splitter applications. The poled structures, which may form gratings in thin film or bulk configurations, may be combined with waveguide structures. Electric fields applied to the poled structures control routing of optical energy. In a particular embodiment, an electrode confronts a solid material and bridges at least two elements of a grating disposed transverse of two waveguide segments and overlaps evanescent fields of optical energy in one of the waveguide segments. A switchable grating consists of a poled material with an alternating domain structure of specific period. In a further embodiment there may be an optically active cladding between a grating and a waveguide. Additional electrodes may be provided for independent tuning of the cladding and the grating structure.

Abstract: A system for writing a Bragg grating point-by-point in an optical waveguide includes an illumination system for producing a primary beam. It further includes a diffraction grating to receive the primary beam and to produce a zero order secondary beam and two symmetrical secondary beams of higher order and a focusing optical device for focusing the secondary beams onto a writing area of the waveguide. The diffraction grating and the focusing optical device define an intensity function of writing in the area of the guide including a central peak and two secondary peaks spaced from the central peak by a distance equal to the pitch of the grating.

Abstract: An electro-optic optical modulating apparatus comprises an optical waveguide, which has electro-optic effects, and at least a single pair of electrodes, which are located in the vicinity of the optical waveguide. A driving circuit applies a radio-frequency voltage across the electrodes. A modulating circuit modulates the amplitude of the radio-frequency voltage in accordance with a predetermined signal. The amount of a modulated optical wave is thus prevented from fluctuating due to a DC drift phenomenon.

Abstract: Optical component adapted to monitor a multiwavelength link for use as an add-drop multiplexer in optical networks. The optical component includes an input fiber (68) for transmitting signals of different wavelengths, a diffraction grating (70) for dispersing these signals on several orders of diffraction, fibers (72, 74, 76 and 78) for recovering the dispersed signals corresponding to a given order of diffraction, and fibers (79, 80, 82, and 84) for recovering the same signals but corresponding to another order of diffraction so as to monitor the state of these signals.

Abstract: Ferroelectric domain regions are formed in a ferroelectric crystal cut so that the polarization direction is in the plane of the crystal and is along the z direction is disclosed. A periodic ion exchange grating on the surface of the crystal with grating is provided on the surface of the crystal with grating lines parallel to the Z-axis of the crystal by a combination of photolithography and ion-exchange techniques and then applying a uniform field across two electrode pads on the crystal surface, thus creating an electric field opposite to the polarization direction (+Z direction) of the crystal. The electric field reverses the domains in selective regions defined by the ion exchange grating formed in the earlier step. This gives rise to a periodically reversed domain grating on the crystal surface.

Abstract: A projection display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels. This invention provides an all solid-state, full color, high resolution projection display suitable for displaying computer generated information and full motion HDTV.

Abstract: Optical systems use tuning of in-fiber gratings to provide an optical crossbar switch matrix of switch elements. The switch elements have a drop tap and an insert tap. A combination of the switch matrices provides a flexible way of connecting any of a plurality of transmitters with any of a plurality of receivers. A distribution arrangement has a distribution station with a plurality of serially arranged modulators, each modulating a different and corresponding optical carrier supplied by optical fiber thereto. The modulated carriers are supplied by a distribution fiber to a serially arranged plurality of passive taps, each of which drops an optical carrier corresponding to the tap and supplies it to a local transceiver. The distribution arrangement may include an arrangement where a local transceiver reflects back the modulated optical carrier and modulates it with a return signal.

Abstract: A fibre Bragg grating is used to stabilize the intensity and frequency fluctuations of a diode laser. The diode laser is connected with an opto-mechanical apparatus to the fibre which contains the grating. The grating is formed in the guided-mode region of the optical fibre. The wavelength of maximum grating reflectivity is selected to lie near the maximum of the diode laser gain bandwidth. The magnitude and bandwidth of the grating reflectivity stabilizes the diode laser output without appreciably reducing the optical output power from the end of the fibre. The bandwidth of the optical spectrum of the diode laser is selected depending on the distance of the grating from the diode laser.

Abstract: At least a part of a first coherent beam of monochromatic light is incident bliquely on the reflecting surface of a mirror to produce a reflected beam in a direction different from that of the first beam. An interference pattern is produced within a volume defined by the intersection of the reflected beam with the first beam. A part of an optical fiber is positioned in the volume containing the interference pattern, and a grating is photo-induced in the optical fiber by exposure of the optical fiber to the interference pattern. A desired Bragg period in the grating can be selected by tilting the mirror to change the interference pattern.

Abstract: An optical deflection scanning device has a transducer, a waveguide medium for unidirectionally propagating an elastic wave based on the oscillation of the transducer. The light emitted from a light source is incident to the waveguide medium in a direction opposite the group velocity of the elastic wave in the waveguide medium. The incident light and elastic wave interact, and the incident light is deflected within the same plane as the waveguide medium in conjunction with elastic wave travel.

Abstract: The present invention provides a method and apparatus for controlling the detailed strain field imposed on a guided-wave Bragg grating. The spectral and temporal form of radiant energy traveling down optical fibers is important in many fields, including communications and sensing. The spectral distribution and center wavelength of short optical pulses is of particular importance. In the communication field the information carrying capacity of an optical fiber can be limited by the dispersion experienced by short pulses as they propagate along an optical fiber. Chirped fiber optic intracore Bragg gratings can be used to compensate for this dispersion. However, a grating with a different degree of chirp would be required for each particular communication system.

Abstract: Optical fiber devices include optical fibers having grating portions with in-fiber gratings having optical characteristics which are changed by the use of strain inducing members. The strain inducing members are connected to optical fibers in such a way that the strain applied to an in-fiber grating in an optical fiber is greater than the strain in the strain inducing members. Basically, a given percentage change in a dimension of one of the strain inducing members causes a greater percentage change in a dimension of the grating portion. The strain inducing members may apply lengthwise or radial strain to the grating portion. Arrangements with mechanical coupling of two fibers using one or more strain inducing members are useful for producing equal strain in grating portions of two fibers for interferometer configurations or other applications.

Abstract: An optical scanning device of the thin film waveguide type, which has a scanning speed and excellent scanning accuracy that can be used in a laser beam printer, a digital copier, a facsimile apparatus or the like, and an image forming apparatus using the optical scanning device are disclosed. The optical scanning device comprising: a thin film waveguide; a light source for emitting a plurality of laser beams to the thin film waveguide; a comb-like electrode for exciting a surface acoustic wave for deflecting the laser beams in the thin film waveguide; and a plurality of emitting means for emitting the deflected laser beams to an outside of the thin film waveguide, the emitting means being equal in number to the laser beams is disclosed. In an embodiment, the plurality of emitting means are located at the same position in a traveling direction of the incident laser beams, and have different emittance angles.

Abstract: A linear chirp is imposed on a fibre Bragg grating by means of a temperature gradient impressed on the grating. An optical fibre containing a fibre Bragg grating is set in a groove in an elongated plate. A temperature gradient is imposed on the plate by the applying heat to each end of the plate containing the optical fibre. The heat is applied by means of Peltier effect plates which sandwich each end of the elongated plate. Thermistors are applied to the elongated plate between the Peltier effect plates to provide feedback as to the temperature of the elongated plate and to enable an estimate to be made of the gradient across the fibre Bragg grating.

Abstract: Improvements in distributed feedback optical reflection filters are described. In particular, taper shapes for the optical reflection couplers are determined by a design method based on a variational optimization theory, to provide an out-of-band sidelobe suppression ratio of greater than -30 dB, and a reduced width of the filtered bandwidth for a specified side lobe suppression level. These filter characteristics were determined by specifying the interaction strength reflection function along the length of the coupler, by the design formulaK.sub.S (z)=L.sub.o (z)+SL.sub.1 (z)+S.sup.2 L.sub.2 (z)+S.sup.3 L.sub.3 (z )where K.sub.S (z) is the interaction strength; S is the desired sidelobe level in .vertline.dB.vertline. L.sub.i (z) (i=0,1,2,3) are functions of the propagation distance z.The functions L.sub.i (z) are given by: ##EQU1## where L.sub.c is the physical length of the coupler, and the set of constant coefficients b.sub.i,j are given by:______________________________________ b.sub.

Abstract: A flat panel display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels.

Abstract: A fibre Bragg grating is used to stabilize the intensity and frequency fluctuations of a diode laser. The diode laser is connected with an opto-mechanical apparatus to the fibre which contains the grating. A polarization maintaining fibre is used. The grating is formed in the guided-mode region of the optical fibre using photorefractive techniques. The wavelength of maximum grating reflectivity is selected to lie near the maximum of the diode laser gain bandwidth. The magnitude and bandwidth of the grating reflectivity is sufficient to stabilize the diode laser output without appreciably reducing the optical output power from the end of the fibre. The bandwidth of the optical spectrum of the diode laser is increased or decreased relative to the solitary diode laser operating characteristics depending on the distance of the grating from the diode laser.

Abstract: A new class of energy interaction devices, particularly optical energy transfer devices and energy guiding devices, use an energy field, particularly an electric field, applied to a poled structure to control energy propagation in a solid material. The poled structures, which may form gratings in thin film or bulk configurations, may be combined with waveguide structures to guide energy beams such as optical or acoustic beams. Electric fields applied to the poled structures, such as electrically-activated gratings, control routing of optical energy. Optical devices include but are not limited to, frequency-selective switchable- and adjustably-tunable reflectors, splitters, directional couplers, frequency-tunable switches and efficient beam combiners, as well as polarized beam combiners, am and fm modulators, mode selectors, energy transfer devices, optical data readers, panel display devices, and waveguide/reflector switching arrays.

Abstract: An optoelectronic device for coupling between an external optical wave and a local optical wave. The local wave is supported by a multiplicity of electrodes and a structure associated with the electrodes. The electrodes are spaced in a substantially regular pattern and are adapted for two functions. First, the electrodes resonantly couple between the external wave and the local wave. Second, the electrodes allow a potential difference between adjacent electrodes.

Abstract: An integrated tunable optical filter comprising a substrate made of a semiconducting material. The substrate includes first and second sections. The first section forms a tunable transmission filter, based on a codirectional coupler having a low selectivity. The second section forms a reflection filter with a reflection spectrum containing a number of peaks. A first injector, designed for current injection into said first section, is provided. Thus, the filter response of the first section is shifted in wavelength over a large wavelength range. There is also a second injector, designed for current injection into the second section. As a result, the reflective spectrum of the second section is slightly shifted in wavelength, in such a way that one reflection peak of the reflection spectrum corresponds to the coupling wavelength of the first section. Consequently, the total filter response has a very narrow bandwidth and wide tunability.

Abstract: An optical device for performing a light power transfer between two waveguides that includes a first waveguide, a second waveguide, a transfer rate control element for controlling a light power transfer rate between the first and second waveguides and an electric element for electrically controlling the transfer rate control element by imparting electric energy to the transfer rate control element. The transfer rate control element sets the light power transfer rate to zero when the transfer rate control element is in an inoperative state. The transfer rate control element falls into the inoperative state when the electric element imparts no electric energy to the transfer rate control element.

Abstract: An electro-optical semiconductor modulator includes two successive segments (SA, SD) each of which applies both attenuation and a phase shift to a light wave (12) in response to a control voltage for controlling the segment. The two segments belong to the same structure having multiple quantum wells. A control generator (4) develops the AC components of the two control voltages (MA, MD) respectively in the form of two different combinations of a reference attenuation (A) and of a reference phase shift (D) to be applied to the light wave (12). The control generator also supplies two DC components (VA, VD) of the control voltages with two different values that are chosen so as to enable the two combinations to actually apply the attenuation (A) and the phase shift (D) to the wave. The invention is applicable in particular to implementing an optical link having a high data-rate.

Abstract: The efficiency of an N.times.N waveguide grating router may be increased in many applications by incorporating at least one output waveguide, such as an (N+1).sup.st waveguide, positioned for capturing second order diffraction optical energy from a free-space region in the router. The second order diffraction optical energy is delivered at a wavelength or at wavelengths corresponding to that wavelength or those wavelengths output on a particular associated one of the original N waveguide outputs for the router.

Abstract: The present invention relates to optical amplifier systems which include optical add/drop multiplexing capabilities. The optical amplifier system includes a first optical circulator with at least three circulator ports. An optical transmission fiber optically communicates with the first circulator port for transporting a wavelength division multiplexed (WDM) optical transmission signal. A section of optically amplifying rare-earth doped fiber amplifies the WDM optical transmission signal input to the first circulator port. A wavelength-selecting optical fiber including at least one in-fiber Bragg grating for selectively reflecting an optical signal of a particular wavelength from the WDM optical signal optically communicates with the second circulator port. The optical amplifier system further includes a second optical circulator with at least three optical circulator ports, one of which communicates with the wavelength-selecting optical fiber.

Abstract: An optical wavelength selective device is provided that is particularly useful as a demultiplexer. The device is made from a planar slab optical waveguide material transmissive to light. Perturbations in the form of holes are etched into the slab waveguide cladding or preferably into the core of the waveguide thereby changing the effective refractive index of regions within the core. The holes are very closely spaced and form a transmissive optical grating, having dimensions suitable for operating in the Raman-Nath regime. Mirrors or lenses are formed within the device for guiding an input beam into the waveguide as a parallel light source.

Abstract: Optical energy transfer devices and energy guiding devices use an electric field to control energy propagation using a class of poled structures in solid material in a channel dropping filter and splitter applications. The poled structures, which may form gratings in thin film or bulk configurations, may be combined with waveguide structures. Electric fields applied to the poled structures control routing of optical energy. In a particular embodiment, an electrode confronts a solid material and bridges at least two elements of a grating disposed transverse of two waveguide segments and overlaps evanescent fields of optical energy in one of the waveguide segments. A switchable grating which consists of a poled material with an alternating domain structure of specific period. In a further embodiment there may be an optically active cladding between a grating and a waveguide. Additional electrodes may be provided for independent tuning of the cladding and the grating structure.

Abstract: Computation-intensive applications such as sensor signal processing, sensor fusion, image processing, feature identification, pattern recognition, and early vision place stringent requirements on the computational capacity, size, weight, and power dissipation of modular computational systems intended for both embedded and high performance computer environments. Such ultra high speed, ultra high density computational modules will typically be configured with multiple processor, memory, dedicated sensor, and digital signal processing chips in close-packed multichip modules. The present invention relates to a novel architecture and associated apparatus for the development of highly multiplexed photonic interconnections between pairs of such electronic chips incorporated in vertical stacks within three-dimensional multichip module configurations.

Abstract: A waveguide type electro-optical element is made up of a proton-exchanged optical waveguide formed on a substrate which possesses an electro-optical effect. At least one pair of electrodes is formed on the substrate adjacent to the optical waveguide with a buffer layer being disposed between the substrate and the electrodes. A guide beam propagating through the waveguide is diffracted as a result of the application of a voltage to the electrodes. The buffer layer is made of material which has a specific resistance ranging between 10.sup.7 -10.sup.11 .OMEGA.cm. The optical waveguide may be of a form having a split-type optical waveguide consisting of the combination of two Y-shaped waveguides, and a pair of channel optical waveguides constituting a directional coupler.

Abstract: A method is described for selectively modifying the refractive index of an optically transmissive body having an optical propagation axis. According to this method, polarized, actinic radiation is impinged on at least a portion of the body. In contrast to methods of the prior art, the actinic radiation is at least 60% polarized with a polarization direction parallel to a plane containing the propagation axis.

Abstract: A multichannel optical head and data storage system employs an integrated-optical read channel. The read channel may be fabricated on a planar waveguide structure that separates the data signals of the multiple lasers. The read channel includes focus error sensors and track error sensors. The optical head may be used for amplitude recording systems such as phase-change erasable and write-once media, ablation media, dye-polymer media, and OD-ROM systems.

Abstract: An improved optical fiber modulator producing a focused acoustic wave propagating from an acoustic transducer surrounding an optical fiber having an in-fiber reflection grating changes the core refractive index in proportion to the induced strain at the core when the focused acoustic wave arrives at the optical fiber core, and focused acoustic waves can also modulate optical carrier phase in a length of optical fiber which may lie in an arm of an interferometer. In a preferred embodiment, the index change shifts the reflection spectrum of an in-fiber grating located in the portion of optical fiber core on which the focused acoustic wave is centered with the reflection spectrum shift producing a change in the grating reflectivity for a narrow bandwidth optical signal on a skirt of the grating spectrum.

Abstract: A passively aligned optical interconnect is described for use as a wavelength division multiplexer (WDM) and demultiplexer. The device makes use of silicon waferboard for a low cost interconnect. Computer generated holograms are used to effect the multiplexing/demultiplexing as well as focusing of the beams. In an alternative embodiment, the device is used as a beam splitter for monochromatic light. In yet another embodiment, the device is used to spatially separate the polarization states of light.

Abstract: A compact optical transceiver including a ceramic mounting block 1, with a laser diode 3 abutting a first end of the mounting block for generating light of a first wavelength. A holographic optical element (HOE) 5 is positioned adjacent laser diode 3 and acts as a hologram lens which receives and focuses the generated light to the end face of an optical fiber 13 which is attached to the compact optical transceiver. A glass element 7 is mounted on the mounting block between the diode and the optical fiber end face, and includes dichroic substance 8 coated to the fiber-proximate side of the glass element 7 and acts as a beamsplitter by passing light of a first wavelength and deflecting light of a second wavelength. The glass element 7 is mounted in an angular positioning groove of the mounting block. The beamsplitter 8 receives and passes the generated light of the first wavelength which has been focused by the HOE 5.

Abstract: A fibre Bragg grating is used to stabilize the intensity and frequency fluctuations of a diode laser. The diode laser is connected with an opto-mechanical apparatus to the fibre which contains the grating. The grating is formed in the guided-mode region of the optical fibre using photorefractive techniques. The wavelength of maximum grating reflectivity is selected to lie near the maximum of the diode laser gain bandwidth. The magnitude and bandwidth of the grating reflectivity is sufficient to stabilize the diode laser output without appreciably reducing the optical output power from the end of the fibre. The bandwidth of the optical spectrum of the diode laser is increased or decreased relative to the solitary diode laser operating characteristics depending on the distance of the grating from the diode laser.

Abstract: An electrically controllable filter device is provided which comprises an electrode structure which induces a filter for waves within a given wavelength range. The electrode structure is so formed that it within the given wavelength range acts as a filter merely upon electrical feeding whereas it in the absence of electrical feeding has no filtering effect. Furthermore, the electrode structure is so arranged that the filter depending on how the electrode structure is fed can be tuned to a number of different discrete frequencies.

Abstract: An optical repeater is comprised by an amplifying optical fibre (5) and directional coupler means (3). An input pulse (1) is reflected, by a respective grating (7) written in the optical fibre, in dependence on the spectral content of the pulse (1). The output pulse (8) is thus reshaped (amplified) and narrowed spectrally. The gratings have different spacings, at least in use of the repeater, so that output pulses with predetermined characteristics can be achieved.

Abstract: Apparatus and method for amplitude modulation of laser light by means of an electro-optic waveguide having a grating coupler, the length of the grating being short relative to the coupling length and to the waist of the incident laser beam.

Abstract: An optical integrated circuit is disclosed. The optical integrated circuit includes: a dielectric waveguide having at least a waveguide layer for transmitting light in a first direction; a first reflector for reflecting the light in a substantially opposite direction to the first direction, the first reflector being formed on an end face of the waveguide layer; a grating coupler having a grating for diffracting at least a part of the light in a second direction which is different from the first direction, the grating coupler being formed at a surface of the waveguide layer; and a light detector for detecting the diffracted light, the light detector being optically connected with the dielectric waveguide.

Abstract: A process for making an optical reflection grating in a glass fiber includes exposing an unjacketed optic fiber to a single writing pulse from a pair of interfering light beams that form an interference pattern in the fiber. A novel optical fiber has at least one optical grating with a preselected Bragg spacing in at least one region of the fiber, with a periodic modulation in its index of refraction, with high thermal stability and narrow linewidth. A process for making an array of optical reflection gratings in a glass fiber includes exposing a fiber to a plurality of writing pulse from a pair of interfering light beams that form an interference pattern in the fiber, where these pulses are applied sequentially as the fiber is drawn from a draw furnace. A novel optical fiber has a plurality of unspliced gratings with high thermal stability and narrow linewidth.

Abstract: An optical speed sensor includes a laser diode 10 that provides a broadband source light 12 to a coupler 18 which provides a source light 22 to a fiber Bragg grating 26 which reflects a first reflection wavelength of light 28 and passes the remainder as a light 30. The light 30 is incident on another fiber Bragg grating 32 which reflects a second reflection wavelength of light 34. The power of an output signal 40 is indicative of the reflected light beams 34,28, and is measured by a photodetector 46. The gratings 26,32 are mounted on a magnetostrictive material 60 which is connected to a permanent magnet 62 which is connected to a material 70 which conducts magnetic fields. The material 60 expands and contracts in response to the strength of magnetic fields therein. The reflection wavelengths for both gratings 26,32 are the same when the tooth 100 is not nearby, thereby causing the output signal 40 to be primarily equal to the reflected light 28.

Abstract: An optical modulator is disclosed. The modulator is based upon an ARROW waveguide, consisting of a substrate, a lower cladding, an interference layer, and a core layer. An electronic element is formed in the structure to control the free-carrier concentration in the interference layer. The light is coupled by grating into the interference layer, where the free-carrier concentration is controlled by the element, which in turn controls the modulation of the light in the interference layer before it is coupled back to the core layer.