Abstract: An optical waveguide, such as a rib waveguide, having a first portion (7) to which a dopant (9) and/or a metal layer (10) is applied to enable an optical property of a second portion of the waveguide to be altered, the first portion (7) having a structure, e.g. being corrugated, the geometry of which is such as to prevent an optical wave being carried in the first portion (7). The dopant (9) and/or metal layer (10) can thus be positioned close to the second portion which carries the optical wave without causing perturbation, e.g. attenuation and/or polarization, of the optical wave.

Abstract: A method of making an optics package is described in which an exposed length of optical fiber is deliberately subject to a predetermined bend. The relationship between the exposed length of the optical fiber and a distance between a location at which it is supported and a fixing point on an optical device is determined taking into account the induced strain in the optical fiber. An optics package designed according to the method is also set forward.

Abstract: The application describes the addition of serrations to the edge of the light transmissive layer of an integrated optical device. This enables scattered background light to be coupled out of the device, improving the signal-to-noise ratio.

Abstract: Apparatus connecting electrical circuit boards (1, 2, 3, . . . N) so each board can communicate with each other. Each board has an optical circuit, which in turn has a transmitter module (T) and a receiver module (R). The transmitter module (T) has electrical to optical converters (11B) for converting electrical signals into optical signals, a wavelength multiplexer (12) for multiplexing the optical signals into a single optical waveguide (12A), and an optical splitter (13) for dividing the multiplexed signal into a plurality of identical signals for transmission to each of the receiver modules (R). The receiver module (R) has an optical selector (14) for selecting signals from the transmission modules (T), a wavelength demultiplexer (21) for demultiplexing the selected signal into signals each of a different wavelength (&lgr;1 . . . &lgr;n), and optical to electrical converters (22B) for converting each of the signals of different wavelengths into an electrical signal.

Abstract: An integrated optical circuit formed on an optically conductive substrate having light absorbing means comprising one or more doped areas (1) of the substrate where the doping concentration is greater than that of areas of the substrate forming the optical circuit (2) to absorb stray light in the substrate which is not guided by components of the optical circuit.

Abstract: An optical phase modulator comprises a semiconductor rib wave guide having P and N doped regions forming a PN junction along the path of the rib with terminals for applying a reverse bias to the junction to extend a carrier depletion zone to alter the refractive index, the PN junction is offset from the central axis of the rib but on application of the reverse bias the depletion zone extends over a central axis of the waveguide.

Abstract: An optoelectronic device is mounted on a planar substrate in electrical connection with solder bumps adjacent an edge of the substrate and connection to a lead frame is made by loading the edge of the substrate on a lead frame support with lead frame conductors in engagement with the solder bumps and applying heat to melt the solder.

Abstract: The device comprises an upper silicon layer (10) including two optically connected rib waveguides (3,4) formed in the upper silicon layer (10); a pair of dissimilar materials (6,7) each positioned between the two waveguides (3,4); and an electrical circuit (8,9,13) through the pair of dissimilar materials (6,7), so that an electrical current can be passed through the dissimilar materials (6,7) in both forward and reverse directions, so as to simultaneously heat one waveguide and cool the other waveguide by virtue of the Peltier effect.

Abstract: A thermo-optic semiconductor device has one semiconductor region providing an optical waveguide and an adjacent semiconductor region providing a resistive heater between two doped regions, current may be passed through the resistive heater within the adjacent semiconductor region to heat it and thereby vary the optical characteristics of the waveguide.

Abstract: An integrated optical waveguide with an end face, the end face being provided on an end portion with a greater width than the waveguide, e.g. in the form of a T-bar provided at the end of the waveguide, whereby the rounding effect produced by the manufacturing process, e.g. etching, used to form the end face does not affect the flatness of the portion of the end face through which light is transmitted. The T-bar is preferably inclined so the normal of the end face is inclined to the optical axis of the waveguide to reduce back reflection therefrom. A plurality of waveguides may terminate in a common T-bar.

Abstract: An optical system comprises two optical paths P1, P2, and an optical path changer for changing the optical length of the two optical paths. The optical path changer includes two phase modulators M1, M2 one coupled to each of the paths. A driving system is configured to apply power to the phase modulators to drive them in the same direction and to change the power applied to the phase modulators in opposite directions so as to change the length of each optical path in a different direction. As a result, the relationship between the changes in the power applied to the phase modulators and the resulting changes in the phase of light beams passing through the optical system becomes substantially linear.

Abstract: A process for treating a waveguide structure which comprises a silicon substrate with an integrally formed rib waveguide is described. The waveguide has an end portion with a facet, the end portion overhanging the silicon substrate and having an oxide layer on its underside protruding from the facet of the waveguide. A nitride layer extends over the upper surface of the waveguide and the facet. The treatment process involves etching the oxide layer from the underside, growing a new oxide layer, etching the nitride layer and then depositing a new nitride layer.

Abstract: A hermetically sealed structure, particularly for use in an optoelectronic device is described. The structure comprises an outer sleeve of a material resistant to moisture ingress with an insert located in the sleeve at one end portion thereof and having a bore therethrough. An optical fibre extends through the bore and beyond the end portion of the sleeve with adhesive films respectively securing the insert to the sleeve and the optical fibre to the insert. A method of assembly for such a package is also described.

Abstract: An apparatus is provided for coupling an optical fibre to a waveguide on an optical chip, the apparatus comprises a recess in the chip for receiving the optical fiber, the recess comprising a V-groove the side faces of which locate the position of the fiber in directions perpendicular to the optical axis of the fiber so as to position the fibre in alignment with the waveguide, and an end face adjacent the end of the waveguide, the end face of the recess being substantially flat and substantially perpendicular to the plane of the chip with its normal inclined to the optical axis of the waveguide so an optical fiber having an inclined end face can be brought into a close, abutting relationship with the end of the waveguide and brought into rotational alignment therewith about its optical axis by positioning the fiber so its inclined end face lies in planar contact with the end face of the recess.

Abstract: The present invention is a temperature stable integrated optical device which is substantially insensitive to temperature variations. The device, such as an interferometer, includes sub-sections of a different light transmissive material within the optical pathways. The relative lengths of the two different material waveguides can be selected so as to achieve temperature insensitivity. A suitable balance is to ensure that the ratio of the difference in sub-path lengths of the first and second materials is equal to the ratio of the refractive index gradient with temperature of the second material to the refractive index gradient with temperature of the first material. Preferable materials are silicon and silicon nitride.

Abstract: An integrated optical circuit for use in a fibre optic gyroscope which senses rotation rates by determining a phase shift due to the Sagnac Effect between light beams travelling around an optical fibre sensing loop (4) in opposite directions, the circuit being provided on a silicon-on-insulator chip comprising a layer of silicon separated from a substrate by an insulating layer, the circuit comprising: rib waveguides (11) formed in the silicon layer for receiving light from a light source (2) and transmitting light to a light detector (3), fibre optic connectors (9) in the form of grooves etched in the silicon layer for receiving the respective ends of the optical fibre sensing loop (4); rib waveguides (11) formed in the silicon layer for transmitting light to and from said fibre optic connectors (9) so as to direct light beams in opposite directions around the sensing loop (4) and receive light beams returning therefrom, phase determining means and (13,17,31) integrated in silicon layer for determining a pha

Abstract: An optoelectronic device is mounted on a planar substrate in electrical connection with solder bumps adjacent an edge of the substrate and connection to a lead frame is made by loading the edge of the substrate on a lead frame support with lead frame conductors in engagement with the solder bumps and applying heat to melt the solder.

Abstract: The device is formed on a silicon-on-insulator chip (which comprises a layer of silicon (1) separated from a substrate (3) by an insulator layer (2)) and comprises an integrated waveguide (4) formed in the silicon layer (1) and a reflective facet (6) formed in a recess in the silicon layer (1). The facet (6) is positioned to redirect light in a desired direction. The waveguide (4) and facet (6) are both formed in the silicon layer (1) so their positions can be defined by the same lithographic steps so they are automatically aligned with each other.

Abstract: External Cavity Laser An external cavity laser comprising first and second feedback means with an optical gain medium (2) therebetween, one of the feedback means is provided by a grating (4) formed in a silicon waveguide and the other feedback means is provided by a reflective back facet (2B) of the optical gain medium (2). The output wavelength of the laser, at a given temperature, can thus be determined during its manufacture and the laser can be made by mass production techniques. The grating (4) may be thermally isolated to obviate the need for temperature control means (6) to control the temperature of the grating (4). An array of lasers may be provided on a single chip.

Abstract: An optical device for splitting up a multi-wavelength light beam into a plurality of individual beams, each comprising light of a different wavelength or a narrow beam of wavelengths. The optical device includes an optical grating and an optical system for directing the incident beam onto the optical grating. The incident beam is divided into two portions, and one portion is directed onto the grating in one direction, while the other portion is directed onto the grating along an opposite direction. Preferably the grating is formed in two parts and one beam portion is directed through the two grating parts in succession in one direction while the other beam portion is directed through the two grating parts in succession along an opposite direction. A common mirror may be used to direct light towards the grating and to receive light returning from the grating. The device may also be used as a multiplexer by reversing the direction of light transmitted through the device.