Abstract: A fibre-optic module incorporating a semiconductor optical amplifier is compatible with a standard specification for a fibre-optic transceiver module, which is typically pluggable. The module comprises optical connectors capable of connection to first and second optical fibres and being in accordance with said standard specification and the input optical signal received from the first optical fibre is amplified by the semiconductor optical amplifier and supplied to the second optical connector for transmission along the second optical fibre. The module further comprises an electrical parallel connector having a physical configuration in accordance with said standard specification and a control circuit which receives control signals from the electrical parallel connector and to control the operation of the optical amplifier. Thus the module maybe connected to a standard electrical backplane alongside fibre-optic transceiver modules to augment the optical performance of the transceiver modules.

Abstract: An array of SOAs integrated in a semiconductor chip 1 is optically coupled to an array of waveguides 12 arranged on a substrate 10 of a passive device by mounting the semiconductor chip 1 on the substrate 10 to form a hybrid optical assembly. The semiconductor chip 1 is manufactured with a redundant array of SOAs. In a first aspect, the array of SOAs A1, A2, etc are arranged with a pitch equal to the predetermined pitch at which the array of waveguides 12 are arranged on the substrate 11 divided by an integer greater than 1. In a second aspect, the SOA A, B, C are arranged at the same predetermined pitch at which the array of waveguides 12 are arranged, but the number of SOAs A, B, C in the array on the semiconductor chip 1 is greater than the number of waveguides 12 arranged on the substrate 10.

Abstract: A method of aligning the end of an array of optical fibers 27, such as ribbon fiber, with waveguides 33 in an optical device 31, such as an active semiconductor optical device. The ends of the optical fibers 27 are mounted in grooves 25 in a grooved surface 23 of a first block 21 of a fiber block assembly 20. A second block 22 is mounted to the grooved surface 23 of the first block 21 with the fibers 27 mounted between the blocks 21, 22. The grooved surface 23 of the first block 21 extends beyond the second block 22 to form guide surfaces 30. The optical device 31 is supported on a support surface 36 of a bench 32 having guide surfaces 37 extending from the support surface 36.

Abstract: A liquid crystal display device comprises: a layer of a chiral liquid crystal material disposed between first and second substrates; and means for applying a voltage across the liquid crystal layer. A first region of the liquid crystal layer is an active region for display and a second region of the liquid crystal layer is a nucleation region for generating a desired liquid crystal state in the first region when a voltage is applied across the liquid crystal layer. The ratio of the thickness d of the liquid crystal layer to the pitch p of the liquid crystal material has a first value (d/p)A in the first region of the liquid crystal layer and has a second value (d/p)N different from the first value in the second region of the liquid crystal layer.

Abstract: A liquid crystal device comprises pixels which are switchable between a white state and a black state. Spacers are disposed in gaps between the pixels and are birefringent such that the spacers have the same optical properties as liquid crystal in the black state. For example, the spacers may have the same retardation as the liquid crystal layer with an optic axis fixed in the direction of the optic axis of the liquid crystal when in the black state.

Abstract: A charge-transport structure, e g an opto-electronic structure such an electroluminescent device is manufactured by forming a uniform first charge-transport (eg electron-transport) polymer layer on a substrate. Low molar mass dyes in a solvent are ink-jet printed onto the exposed surface of the first layer to form a multicolor pattern, and the dyes are allowed to diffuse into the layer to form charge-recombination/emitter regions within the layer. Excess dyes are washed away from the surface and then a uniform second charge-transport (eg hole-transport) polymer layer is formed on the resultant smooth surface of the first layer over the tops of the regions. Finally, electrodes are deposited on the top of the second layer in registration with the regions. Photovoltaic structures and organic transistors are also disclosed.

Abstract: A method of aligning the end of an array of optical fibers 27, such as ribbon fiber, with waveguides 33 in an optical device 31, such as an active semiconductor optical device. The ends of the optical fibers 27 are mounted in grooves 25 in a grooved surface 23 of a first block 21 of a fiber block assembly 20. A second block 22 is mounted to the grooved surface 23 of the first block 21 with the fibers 27 mounted between the blocks 21, 22. The grooved surface 23 of the first block 21 extends beyond the second block 22 to form guide surfaces 30. The optical device 31 is supported on a support surface 36 of a bench 32 having guide surfaces 37 extending from the support surface 36. The ends of the optical fibers are aligned with the waveguides 33 in the optical device 31 by moving the fiber block assembly 20 with the guide surfaces 30 of the first block 21 in contact with the guide surfaces 37 of the bench 32. This allows adjustment of the alignment in the direction in which the fibers 27 extend and laterally.

Abstract: A semiconductor optical amplifier comprising an active gain region of the (In, Ga)(As, N) system is proposed, together with the use of (Ga,In)(As,N) as the base material for the fabrication of an SOA, and a semiconductor optical amplifier comprising (Ga,In)(As,N) as the base material. The N content of the (In,Ga)(As,N) can be varied along a dimension of the active region in the direction of propagation of light signals therein, to create a varying bandgap such as for mode expanders. The active region can be supplied by a source of electrical bias which is applied in segments along the dimension of the active region, the segments being capable of independent variation. This should allow channel equalisation of WDM signals to be performed dynamically. This scheme could also be used to equalise device parameters such as differential gain, saturation output power and linewidth enhancement factor across the amplification bandwidth.

Abstract: A semiconductor optical amplifier comprising an active gain region of the (In, Ga)(As, N) system is proposed, together with the use of (Ga, In)(As, N) as the base material for the fabrication of an SOA, and a semiconductor optical amplifier comprising (Ga, In)(As, N) as the base material. The N content of the (In, Ga)(As, N) can be varied along a dimension of the active region in the direction of propagation of light signals therein, to create a varying bandgap such as for mode expanders. The active region can be supplied by a source of electrical bias which is applied in segments along the dimension of the active region, the segments being capable of independent variation. This should allow channel equalisation of WDM signals to be performed dynamically. This scheme could also be used to equalise device parameters such as differential gain, saturation output power and linewidth enhancement factor across the amplification bandwidth.

Abstract: A lasing structure comprises a distributed feedback grating associated with the active region, the grating defined by a periodic structure of quantum well intermixing. This quantum well intermixing (QWI) can be caused by focussed ion beam (FIB) implantation to the quantum well (QW) or multi-quantum well (MQW) active area. Subsequent annealing of the FIB damage will leave local periodic adjustments to the energy levels in the active region, providing the necessary DFB/DBR grating. Alternatively, or in addition, this periodic QWI structure or another periodic variation can be separated from the active region but associated therewith. For example, a QW or MQW structure which overlies the active region will carry the evanescent part of the waveform that is propagating in the active region. A periodic QWI structure in this region will thus affect the waveform.

Abstract: A tunable semiconductor laser comprises a propagation region in which a waveform can exist, the propagation region comprising sequential gain and control regions, the gain region comprising a light amplification region supplied by a source of excitation, and the control region comprising a periodic structure through which the waveform propagates. The control region can be linked to a source of current thereby to enable changes to be made to the refractive index thereof. It is preferred that the material of the propagation region is (Ga,In)(N,As). As a result, in the gain region the waveform will be less tightly confined and hence a higher gain can be produced without suffering from saturation of the gain material. Ideally, there will be tight confinement of the waveform in the control region to allow maximum advantage to be made of the change in refractive index.

Abstract: A diffractive spatial light modulator comprises first and second substrates (1, 2) between which an optical path is defined comprising, in order, first (8a,8b), second (5,6), and third (8a,8b) half wave retarders. The second retarder (6,5) has a fixed optic axis (9c) whereas the first and third retarders have switchable optic axes (9a,9b). The fixed optic axis (9c) is oriented outside the switching ranges of the switchable optic axes (9a,9b). The modulator is pixellated and each pixel comprises a switchable phase-only diffraction grating. Each pixel is switchable between a first mode in which incident light is output in the zeroth order diffraction lobe and a second mode in which incident light is deflected into higher order diffraction lobes. The spatial light modulator may be used in high brightness projection displays.

Abstract: A liquid crystal display device comprises: a layer of a chiral liquid crystal material disposed between first and second substrates; and means for applying a voltage across the liquid crystal layer. A first region of the liquid crystal layer is an active region for display and a second region of the liquid crystal layer is a nucleation region for generating a desired liquid crystal state in the first region when a voltage is applied across the liquid crystal layer. The ratio of the thickness d of the liquid crystal layer to the pitch p of the liquid crystal material has a first value (d/p)A in the first region of the liquid crystal layer and has a second value (d/p)N different from the first value in the second region of the liquid crystal layer.

Abstract: A Liquid crystal device includes: first and second substrates; a layer of liquid crystal disposed between the first and second substrates: and a plurality of picture elements. Each of the picture elements includes: a first electrode disposed on the first substrate; a second electrode electrically insulated from and disposed above the first electrode relative to the substrates; and a third electrode disposed on the second substrate.

Abstract: A display device includes a plurality of strobe electrodes and a plurality of pairs of data electrodes crossed with the strobe electrodes to define a respective pixel at each overlap of one of the strobe electrodes with one of the pairs of data electrodes. The display device further includes a strobe signal source for simultaneously supplying X different strobe signals to each group of X strobe electrodes in turn, where X is an integer greater than one, and a data signal source for supplying any one of a plurality of data signals to the data electrodes such that all combinations of optical states of the X pixels addressed by each group of strobe electrodes and each pair of data electrodes are selectable.

Abstract: A diffractive spatial light modulator of the present invention includes a plurality of picture elements, each of the plurality of picture elements, comprises a plurality of first elongate parallel electrodes, a plurality of second elongate parallel electrodes interdigitated with the first electrodes and a third electrode, facing the first and second elongate parallel electrodes; and an address signal generator connected to the first and second elongate parallel electrodes and arranged to supply addressing signals for selectively switching each of the plurality of picture elements, picture element to any one of a non-diffractive state and a plurality of diffractive states of different diffraction efficiencies.

Abstract: A spatial light modulator, for instance of the diffractive liquid crystal type, comprises an addressing circuit and a plurality of pixels. Each of the pixels has a plurality of first elongate electrodes and a plurality of second elongate electrodes interdigitated with the first electrodes. The first electrodes are connected to the addressing circuit whereas the second electrodes are electrically floating.

Abstract: An address generator for a display or spatial light modulator, comprising a first shift register having a plurality of cascade-connected stages for controlling respective first address electrodes of the display or spatial light modulator. The stages of the first shift register include a first reconfigurable shift register stage which is selectively operable in an alternate mode, in which the output of the first reconfigurable shift register stage follows the output of a preceding stage.

Abstract: A diffractive liquid crystal device includes a bistable liquid crystal arranged as pixels with each pixel being addressed by a strobe electrode and a pair of interdigitated data electrodes. A strobe generator supplies an initial blanking pulse to each of the strobe electrodes and then supplies strobe pulses in sequence to the strobe electrodes for at least several frames without any more blanking pulses. A data signal generator supplies data signals to the pairs of data electrodes which switch each pixel to a diffractive or non-diffractive state irrespective of its previous state. In particular, the strobe signals comprise pulses of opposite direction in consecutive frames. To select the non-diffractive pixel state, switching signals are applied to both the first and second electrodes during each frame.

Abstract: A spatial light modulator includes at least three picture elements, each of which includes a plurality of first elongate electrodes which are connected together and a plurality of second elongate electrodes which are connected together and which are interdigitated with the first electrodes. The first electrodes of a second of the picture elements are connected to the second electrodes of a first of the picture elements and the second electrodes of the second picture element are connected to the first electrodes of a third of the picture elements.