Abstract: An optical subassembly includes a substrate, a heat spreader, and a submount. The submount has a submount mounting surface and a component mounting surface with either the submount mounting surface or the component mounting surface including an angle. The submount is positioned on either the heat spreader or the substrate such that the component mounting surface is positioned at the angle relative to the substrate. An optoelectric device is positioned on the component mounting surface and coupled to interconnects on the substrate. The optoelectric device is thermally coupled to the heat spreader through the submount to provide a low thermal resistance between the optoelectric device and the heat spreader. An encapsulant structure is mounted on the substrate and hermetically encloses the optoelectric device. The encapsulant structure includes a window positioned to pass light between the optoelectric device and an externally mounted optical fiber.

Abstract: A system is provided for producing wavelength tunable laser light and a signal indicative of the wavelength of the produced laser light; a laser cavity includes an optical gain medium and a wavelength selective element disposed in a path of light emitted by the optical gain medium such that changing a position of the element changes a wavelength emitted by the medium; a position sensor that senses position of the element; position signal circuitry that produces a position signal indicative of position of the element sensed by the position sensor; a storage medium storing at least one position signal corresponding to a respective predetermined position of the element; comparison circuitry for comparing the produced position signal with the at least one stored position signal and for producing a comparison result indicative of whether the element has reached to the predetermined position; marker signal circuitry providing an external wavelength marker signal when the comparison result indicates that the element

Abstract: A tuneable laser has a gain section bounded at one end by a first reflector in the form of a distributed Bragg reflector adapted to produce a comb of reflective peaks and on the other end by a second Bragg reflector, the second Bragg reflector adapted to reflect at a plurality of wavelengths and being capable of being varied selectively through discrete segments so that one or more segments of the Bragg reflector can be tuned to a lower wavelength to reflect with a segment reflecting at that lower wavelength to enhance the reflectivity at that lower wavelength.

Abstract: Gain-flattening components for compensation of at least a portion of the spectral gain profile of an optical amplifier comprises an optical substrate having at least a first gain-flattening filter disposed on a first surface of the optical substrate and a second gain-flattening filter disposed on a second surface of the optical substrate. The first gain-flattening filter has a transmission curve with a spectral loss profile for optical signals in the optical wavelength range, and has a net insertion loss error function relative to the spectral gain profile of an optical amplifier. The spectral loss profile of the second gain-flattening filter corresponds to the net insertion error function of the first gain-flattening filter. Gain-flattening optical amplifiers comprise one or more such gain-flattening components and at least one optical signal amplifier.

Abstract: A multistage optical amplifier is controlled to compensate for the effect of amplified spontaneous emission (ASE) by a method comprising the following steps. Optical input and output signals to a first gain stage are detected, and the drive current to the first gain stage is controlled in dependence on the optical input signal to the first gain stage. Optical input and output signals to a last gain stage are detected, and the drive current to the last gain stage is controlled to maintain the output power of the last gain stage substantially constant. The effect of ASE in the first gain stage is compensated for by applying a correction factor based on the ASE of the first gain stage and the output power of the first gain stage.

Abstract: A mover assembly (16) that moves or positions an object (12) includes a mover output (226), an actuator (230), and a control system (18). The mover output (226) is connected to the object (12), and the actuator (230) causes the mover output (226) to move. The control system (18) selectively directs a drive signal to the actuator (230) in a first mode and in a second mode. In the first mode, a peak voltage and a baseline voltage are sequentially directed to the actuator (230). In the second mode an intermediate voltage is directed to the actuator (230), the intermediate voltage being intermediate the peak voltage and the baseline voltage.

Abstract: An apparatus and method for determining a physical parameter affecting an optical sensor or a number of sensors in a network. The apparatus uses a narrow linewidth source at an emission wavelength ?e and an arrangement for varying the emission wavelength ?e of the radiation. An analysis module with curve fitting is used to generate a fit to the response signal obtained from the optical sensor. The physical parameter is determined form the fit rather than from the response signal. The apparatus can be employed with Bragg gratings, etalons, Fabry Perot elements or other optical sensors.

Abstract: A modulator arrangement for modulating an optical signal using a quadrature phase shift key for use in an optical wavelength division multiplex (WDM) optical communications system comprising a laser (2) for producing an optical signal of a selected wavelength, which signal is split by a splitter (4), each part of said split signal being applied to a respective phase modulator (6, 8) each for which phase modulators is adapted to modulate the phase of the signal in dependence on a respective drive voltages. The phase of the output of at least one modulator (6) is shiftable at least in part by a phase shifter (10), the split signals being recombined by an optical recombiner (12) to form an optical phase shift key output, wherein the output power is monitored by a detector (20), the detector signal then being used to drive a feedback arrangement to control electrodes of the phase modulators (6, 8) and/or phase shifter (10).

Abstract: A tuneable laser includes a gain section bounded at one end by a first reflector adapted to produce a comb of reflective peaks and on the other end by a second reflector in the form of a plurality of discrete grating units each capable of reflecting at one of the peaks of the comb, and each grating unit having at least two independently actuable electrodes, which when actuated independently one from the other is capable of reducing the reflectivity of the grating unit and in which at least two of the grating units have different pitches.

Abstract: A tuneable laser having an active section, a phase section and a Bragg reflector comprising a plurality of discrete grating units, at least two of which gratings have a different pitch, wherein current is applicable to at least the grating having a longer pitch, such that the effective wavelength of the grating having a longer pitch can be tuned to the wavelength of the grating having a shorter pitch. A chirp grating can provide the difference in pitch.

Abstract: An optical pulse train generator (2) for use in the transmission of high speed optical data in a return-to-zero (RZ) signalling format is described.

Abstract: The invention relates to the stabilization of high power semiconductor laser diode sources as they are extensively used in the field of optical communication. Such lasers are mostly employed as so-called pump laser sources for fiber amplifiers, e.g. erbium-doped fiber amplifiers, and are designed to provide a narrow-bandwidth optical radiation with a stable power output in a given frequency band. To improve the wavelength locking range of such laser sources when operating without an active temperature stabilizing element, an external reflector providing very high relative feedback is used. The reflectivity bandwidth of the external reflector is broadened for improving the stability of the laser source. In commonly employed optical fibers for conducting the laser beam, the external reflector is formed by one or a plurality of appropriately designed fiber Bragg gratings.

Abstract: A tuneable laser having an active section, a phase section and a Bragg reflector comprising a plurality of descrete grating units, at least two of which gratings have a discrete pitch, wherein at least two of the gratings having a different pitch are each provided with a plurality of independently actuable electrodes.

Abstract: The invention relates to high power semiconductor diode lasers of the type commonly used in opto-electronics, mostly as so-called pump lasers for fiber amplifiers in the field of optical communication, e.g. for an erbium-doped fiber amplifier (EDFA) or a Raman amplifier. Such a laser, having a single cavity and working in single transverse mode, is improved by placing a multilayer large optical superlattice structure (LOSL) into at least one of the provided cladding layers. This LOSL provides for a significantly improved shape of the exit beam allowing an efficient high power coupling into the fiber of an opto-electronic network.

Abstract: A Mach-Zehnder interferometer modulator for modulating a beam of laser light includes a pair of separate waveguides through which the laser light is passed after splitting in a splitting zone and after which the light is recombined in a merge zone. The waveguides are formed in a semiconductor material with one of the electrodes of each pair being formed in a doped layer while the other electrode, the top electrode, is a surface metalisation. The doped layer is trenched so that adjacent electrodes in the doped layer are electrically isolated from one another so that one of the electrodes in the doped layer can be connected with a different electrical polarity to the other electrode in the doped layer thereby permitting the connection of the pairs of electrodes in parallel anti-phase mode.

Abstract: An EDF amplifier comprises two EDF loops separated by optical isolators and pumped with light by pump laser diodes under the control of an output power control system. To achieve the required output power the current supplied to the pump supplying light to the input loop is set to the maximum drive current Imax for the pump laser, and the pump currents of all pumps not supplying light to the input loop, that is the pumps supplying light to the further loop or loops, are adjusted to achieve the required output power. To avoid a very high MPI, the inversion of all loops is never so low that the gain in the first loop has to compensate for loss in the following loop or loops. This is done by providing a minimum pump power to the second loop and any following loops. This ensures that the loops are always inverted enough, and that they do not exhibit too much loss. The required minimum pump current is obtained by modelling and experimental verification.

Abstract: The invention is concerned with a method f alignment for aligning crystal planes of a wafer substrate (40) to lithographic features thereon, the method characterized in that it includes the steps of: (a) measuring angular orientation of a peripheral flat (200) of the substrate (40); (b) measuring a crystallographic plane orientation of the substrate (40); (c) determining an error angle (?) between the annular orientation of the flat (200) and the crystallographic orientation; (d) angularly registering to the flat (200) in a lithographic tool; (e) rotating the substrate (40) by the error angle (?); and (f) defining one or more feature layers on the substrate (40) using the lithographic tool, thereby angularly aligning the one or more feature layers to the crystallographic plane orientation.

Abstract: An optical fibre is secured to an electronic package (10) by, firstly, providing in a wall (14) of the package (10) an electrically conductive tube (12), an inductance arrangement (16–22) in magnetically co-operational relation to the tube (12) and a securing agent inside the tube, then secondly inserting the fibre into the tube (12) and passing an RF current through the inductance arrangement (16). The current is such as to melt the securing agent and, when the securing agent is allowed to cool, a bond is formed between the fibre and the tube (12). The package (10) is preferably an LTCC mulilayer package with the inductance (16) being formed in adjacent layers and the tube (12) is preferably composed of a metallic ink which is applied to a stepwise-circular cylindrical cavity likewise formed in adjacent layers.

Abstract: A composite waveguide termination structure including two different waveguide conductor geometries operatively located upon a common substrate, wherein each such waveguide geometry includes a ground conductor on the same surface of the substrate.

Abstract: A method for integrating optical devices in a single growth step by utilizing a combination of Selective Area Growth and Etch (SAGE) is provided. An first device is formed between a set of oxide-masked regions, whilst a second device is formed in an adjacent planar region. By use of Selected Area Growth and Etch (SAGE), in which the growth between the oxide-masked regions is greater than the growth in the planar region, and in which the etch rate in the area between the oxide-masked regions is substantially the same as that in the planar region, the number of active quantum layers for the first device are formed between the oxide-masked regions, and a different number of layers for the second device is formed in the planar region.