Abstract: The invention provides an apparatus (10, 300) incorporating a lithographic tool (20) for printing a pattern from a mask (35) onto a substrate, for example a wafer (190), together with a substrate angle measuring tool (100, 310) employing X-ray diffraction techniques for determining substrate crystallographic orientation. The apparatus (10, 310) is calibrated so that the mask (35) is correctly angularly orientated with respect to the measuring tool (100, 310). When a new substrate (190) is loaded into the apparatus (10, 310) for having the pattern from the mask (35) printed thereonto, the apparatus (10, 300) angularly aligns the substrate (190) relative to the measuring tool (100, 310), thereby also aligning it angularly to the mask (35).

Abstract: An electromagnetic shield that comprises at least a portion formed from a material comprising liquid crystal polymer incorporating an electrically conductive filler, the material having a coefficient of linear thermal expansion, in at least one direction, in the range 1 to 20 ppmK?1 and/or having a electrical conductivity in the range 1 to 1000 Siemens/m.

Abstract: Through the introduction of an imaging multimode interference device in an integrated optical circuit, such performance degradations as lateral waveguide field oscillations and backreflections may be suppressed. The suppression of lateral waveguide field oscillations (that may occur due to misaligned optical coupling), in particular, can significantly reduce variations in the power splitting ratio of an optical power splitting structure, such as those employed by a Mach-Zehnder modulator.

Abstract: An actuator-based latching/delatching mechanism in combination with an optical module includes a housing having a front face with an opening and an optical transceiver designed to be nestingly engaged in the opening. A front surface of the transceiver is flush with the face of the housing in a fully nestingly engaged orientation. A pivot arm is pivotally mounted adjacent a rear end of the housing for pivotal movement between a latching orientation in which the transceiver is fully nestingly engaged in the housing and a delatching orientation in which a force pivots the arm against the transceiver to move the transceiver out of the engaged orientation. An actuator, with an end accessible exterior of the housing, is mounted in the housing for movements from latching to delatching orientations in response to a force applied to the end of the actuator.

Abstract: A tunable laser comprising: a foundation including a first side and an oppositely facing second side and including a hole extending from the first side to the second side; a tuning assembly including a base, a fine tuning arm and a rotational flex bearing disposed adjacent the first side of the foundation; wherein the base is disposed adjacent to the first side of the foundation; wherein one end of the flex bearing is secured to the base; wherein the other end of the flex bearing is secured to the fine tuning arm; wherein a portion of the fine tuning arm extends at least partially into the hole; an external cavity laser including a gain medium, a dispersion medium and a reflective member disposed adjacent to the second side of the foundation; wherein the gain medium and the dispersion medium grating are secured in a fixed relation relative to the each other; wherein the reflective member is secured to the portion of the arm extending into the hole; and a piezoelectric device with one end secured to the base a

Abstract: An optical autocorrelator comprises an optical waveguide (40) of semiconductor material which exhibits two photon absorption at a wavelength at which the autocorrelator is intended to operate. Reflecting means (46) are provided at a part of the waveguide which is remote to an end (42) in which an optical pulse (44) is input for reflecting the optical pulse such as to generate counter-propagating optical pulses in the waveguide. A plurality of electrodes (481-48N) are disposed along the waveguide for measuring a two photon absorption photocurrent (i1-in) generated in the waveguide by the counter-propagating optical pulses.

Abstract: The RF power passing through a given position in a monolithic microwave integrated circuit (MMIC) is determined using the Seebeck effect. The MMIC includes at least certain components of a voltage creating circuit, including a first Seebeck junction on the MMIC at a given position and a second Seebeck junction at a different position. The voltage generated between the two junctions as a result of differential heating caused by the passage of RF power through the given position is measured with a voltmeter. By calibration, the RF power is related to a measured Seebeck voltage created when the circuit is in operation and hence can be determined. The Seebeck circuitry may be independent of the MMIC circuitry or be integrated into the active circuitry of the MMIC itself.

Abstract: To make a grating substructure in semiconductor material for use in a DFB laser, a first layer of semiconductor material is doped at a first doping concentration. A second layer of the semiconductor material is formed over the first layer. The second layer is doped higher concentration than the first layer and sufficiently different to change the refractive index of the semiconductor material. A third layer doped at a concentration comparable with the first layer is formed over the second layer. An etch is performed through a mask to form spaced etched regions extending at least through the second and third layers. Then a further layer of the semiconductor material doped at a doping concentration comparable the first and third layers is overgrown on the wafer.

Abstract: An optical assembly includes a photodetector for detecting light signals. An optical fiber receives an input signal and has a light-emitting portion extending in front of the photodetector. A MEMS actuator is located between the light-emitting portion of the optical fiber and the photodetector. The MEMS actuator is controllably deflectable to partially obscure the photodetector and thereby vary the amount of light received.

Abstract: A system (10) comprises a carrier (1) which is adapted to carry an optical fiber (9) and an optical chip (3) having a circuit element (4). The carrier and the optical chip are provided with co-operable alignment features (13,14) for aligning the carrier with the optical chip so that the optical fiber and the circuit element are optically coupled.

Abstract: An optical spectral filtering device and associated method for selectively directing a portion of a wavelength multiplexed input signal, entering through an optical fiber, into one or more output signals provided to one or more optical fibers and/or electronic outputs. The optical filtering is accomplished using free-space diffractive wavelength demultiplexing optics combined with a fixed (permanent) patterned structure located in the spectrally dispersed image plane. The structure can block or direct a selected spectral portion of the optical signal to one or more separate outputs, such as an optical fiber or power detector. A single active element in the optical path is used to spatially shift, or steer, the entire input spectrum at the dispersed spectral image plane, to control the portion of the input spectrum illuminating specific features on the permanent patterned structure.

Abstract: A current tuned optical attenuator includes a Mach-Zehnder interferometer that relies on the creation of free carriers to create a phase difference in an optical signals along two waveguide arms.

Abstract: A modulator arrangement adapted to use a differential quadrature phase shift key for use in an optical wavelength division multiplex (WDM) optical communications system, comprising a precoder (16), which is adapted to generate drive voltages for first and second phrase modulators (6, 8) in dependence upon first and second data streams. The respective drive voltages for the first and second modulators (6, 8) are fed back to the precoder inputs with a delay related to the line speed of the data system, wherein the length of the delay corresponds to n bits.

Abstract: A signal time-scaling arrangement utilises a known configuration comprising the use of a laser which has its wavelength varied over time, a modulator coupled to the laser and to a modulating analogue electrical source and a dispersion means coupled to the output of the modulator and providing at its output a signal which is a stretched version of the analogue modulating signal, but provides for the modulator to be a single-sideband modulator instead of double-sideband. The effect of this is to enable the use of a much simple laser-control system involving a CW laser output which is wavelength-ramped continuously between quite narrow wavelength limits, while allowing the use of a dispersion means having a wide dispersion characteristic in order to provide the required degree of time-scaling. The invention is application to an ADC system or to a Doppler system.

Abstract: Semiconductor laser diodes, particularly high power ridge waveguide laser diodes, are often used in opto-electronics as so-called pump laser diodes for fiber amplifiers in optical communication lines. To provide the desired high power output and stability of such a laser diode and avoid degradation during use, the present invention concerns an improved design of such a device, the improvement in particular consisting in a way of suppressing the undesired first and higher order modes of the laser which consume energy and do not contribute to the optical output of the laser, thus reducing it's efficiency. Essentially, the novel effect is provided by a structure comprising CIG—for Complex Index Guiding—elements on top of the laser diode. These CIG elements consist of one or a plurality of layers and must contain at least one layer which provides the optical absorption of undesired modes of the lasing wavelength and preferably contains an insulating layer as a first contact layer to the semiconductor.

Abstract: A device comprises a tapered semiconductor optical waveguide which tapers, at an angle of taper with respect to a longitudinal axis of the waveguide, from a relatively wide region to a relatively narrow region, wherein the angle of taper varies along the length of the tapered waveguide such that at all points along the taper it is no greater than, and within a substantially constant angular separation of, the adiabatic limit of the fundamental mode of the waveguide at that point along the taper.

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: A glass fixative composition for bonding glass materials to non-glass materials is provided. The fixative composition is selected for its thermal expansion coefficient, its viscosity, its adhesion to glass, melting point, and bond strength. The glass fixative is in particular useful for bonding optical fibers to metallic materials such as Kovar. The low melting point of the glass fixative enables localized heating methods to be used, in particular, as Kovar is a ferromagnetic material, induction heating can be used to form a bond. The bond formed provides a compressive joint which enables the fiber to be hermetically fixed in position.

Abstract: An asymmetric MEMS thermal actuator device includes a base portion, typically a pair of bond pads, and an actuator element connected to the base portion by a flexure portion. The actuator element has a first arm and a second arm alongside the first arm and spaced from the first arm. The second arm is wider than the first arm so that the actuator element deflects about the flexure element due to differential heating in the first and second arms when an electrical current is passed therethrough. A cut-out portion is provided in the second arm adjacent the first arm so as to increase the spacing therefrom over at least a portion of the second arm. Preferably, a heat sink is also provided laterally adjacent the second arm.

Abstract: A semiconductor device such as a buried heterostructure semiconductor laser includes a semiconductor substrate supporting an active region comprised of a multiple quantum well active region and confinement layers having defined gratings and grating overgrowth regions to produce a laser device. The device also includes a current confinement layer including a sequence of doped n-p-n-p semiconductor layers to produce a n-p-n-p blocking structure and a semi-insulating semiconductor material deposited over the n-p-n-p blocking structure.